Water quality technical report for Murray Lower …...lowlands Water quality technical report for Murray Lower Darling surface water resource plan area (SW8) Summary Good quality water

THE BASIN PLAN

Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)

NSW Department of Planning, Industry and Environment | dpie.nsw.gov.au

Published by NSW Department of Planning, Industry and Environment

dpie.nsw.gov.au

Title: Water quality technical report for the Murray Lower Darling surface water resource plan area (SW8)

First published: February 2020

Department reference number: INT18/36342

Acknowledgments

The soils maps in this report contain data sourced from the NSW Office of Environment and Heritage.

© State of New South Wales through Department of Planning, Industry and Environment [2020]. You may copy, distribute, display, download and otherwise freely

deal with this publication for any purpose, provided that you attribute the Department of Planning, Industry and Environment as the owner. However, you must obtain

permission if you wish to charge others for access to the publication (other than at cost); include the publication in advertising or a product for sale; modify the

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Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (December 2018) and may not be accurate, current or complete. The State of New South Wales (including the NSW Department of Planning, Industry and Environment), the author and the publisher take no

responsibility, and will accept no liability, for the accuracy, currency, reliability or correctness of any information included in the document (including material provided by third parties). Readers should make their own inquiries and rely on their own advice when making decisions related to mate rial contained in this publication.

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Summary Good quality water protects public health, supports economic production and maintains a healthy river ecosystem. Water quality is mostly determined by land use, geology, climate, riparian vegetation and stream flow, and reflects the interactions of natural and man-made practices that occur in a drainage area and the riparian zone.

Degradation of water quality can put stress on a range of aquatic organisms, impinge on Aboriginal cultural and spiritual uses of water, increase the cost of drinking water treatment, contribute to public health risks and decreases the suitability of water for irrigation and agriculture.

Alteration of the Australian landscape since European settlement has resulted in marked changes in catchment conditions. Runoff from cropping areas, erosion of soil and nutrients from stream banks and discharge from saline areas have led to increased turbidity, salinity, sedimentation, nutrient loads and chemical residues. These in turn can degrade aquatic ecosystem health. The regulation of rivers through the construction of large storages and weirs lead to changes to flow regimes, thermal pollution, harmful algal blooms and disruption of longitudinal connectivity of river processes.

Water quality condition in the Murray Lower Darling water resource planning area (WRPA) varies from poor to excellent. Water quality issues occurring within the catchment are the result of a combination of factors. These include alteration to natural flow regimes, in particular disruption by Hume Dam, changes to catchment conditions and land use change. Table 1 summarises the major water quality issues in the Murray Lower Darling WRPA.

Table 1: Summary of major issues and causes of water quality degradation

Issue Location Potential causes

Harmful algal blooms

uplands, midlands, lowlands

Stratification and warm water temperatures in Hume Dam and Menindee Lakes. Seeding of Murray River by Hume Dam and Lake Mulwala. Low flows in Murray and Darling Rivers. Nutrient inputs.

Dissolved oxygen and pH outside of normal ranges


Reduced flow and increased low flow and cease to flow periods disrupting dissolved oxygen dynamics and increased eutrophication.

Increased nutrients and turbidity


Stream bank and riparian condition, grazing and cropping practices, carp and feral species. Increased sediment and nutrient input associated with erosion.

Hypoxic blackwater events

midlands, lowlands

Less frequent flooding allows increased organic material to accumulate on river banks and floodplains.

Poor water

quality events

following

releases

during cease

to flow periods

lowlands Poor water quality events in the Darling River (in terms of dissolved oxygen, salinity

and pH) following the commencement of water releases from Menindee Lakes during

cease to flow periods, flushing of poor quality water downstream from isolated

standing pools.

Thermal

pollution

uplands,

midlands

Cold water released from Khancoban and Hume Dams in summer. Warm water

releases in winter.

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Disruption to organic carbon cycling

midlands, lowlands

Reduced freshes and high flows, disruption of longitudinal connectivity by Hume Dam.

Toxicants and pesticides

midlands, lowlands

Pesticide use in cropping areas.

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Contents Summary ......................................................................................................................................................i

Contents ..................................................................................................................................................... iii

List of tables.................................................................................................................................................v

List of figures............................................................................................................................................... vi

1. Introduction ...........................................................................................................................................1

1.1. Purpose..........................................................................................................................................1

1.2. Context...........................................................................................................................................2

1.3. Catchment description ....................................................................................................................3

1.4. Water quality targets .......................................................................................................................4

1.4.1. Assessment using Basin Plan water quality targets ...................................................................5

1.4.2. Water quality targets for water-dependent ecosystems ..............................................................5

1.4.3. Water quality targets for raw water for treatment for human consumption ...................................6

1.4.4. Water quality targets for irrigation water ....................................................................................7

1.4.5. Water quality targets for recreational water ...............................................................................7

1.4.6. Salinity targets for managing water flows...................................................................................7

2. Water quality parameters .......................................................................................................................8

2.1. Turbidity and suspended sediment ..................................................................................................8

2.2. Nutrients.........................................................................................................................................9

2.3. Dissolved oxygen..........................................................................................................................10

2.4. pH................................................................................................................................................11

2.5. Water temperature and thermal pollution .......................................................................................11

2.6. Salinity .........................................................................................................................................12

2.7. Harmful algal blooms ....................................................................................................................13

2.8. Toxicants......................................................................................................................................14

2.9. Pathogens ....................................................................................................................................14

3. Water access rules and flow management in the Murray Lower Darling WRPA ......................................15

4. NSW Salt Interception Schemes...........................................................................................................17

4.1. Buronga SIS.................................................................................................................................18

4.2. Mallee Cliffs SIS ...........................................................................................................................18

5. Methods ..............................................................................................................................................18

5.1. Site selection and monitoring.........................................................................................................18

5.2. Water quality index (WaQI) ...........................................................................................................23

5.3. Catchment stressor identification ...................................................................................................23

5.3.1. Conceptual mapping ..............................................................................................................24

5.3.2. Literature review ....................................................................................................................24

5.3.3. Summary statistics.................................................................................................................24

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5.3.4. Data analysis .........................................................................................................................24

5.3.5. Spatial and GIS......................................................................................................................24

5.3.6. Local and expert knowledge ...................................................................................................25

5.4. Murray Lower Darling WRPA Risk Assessment..............................................................................25

6. Results................................................................................................................................................26

6.1. Water quality index (WaQI) ...........................................................................................................26

6.1.1. Water-dependent ecosystems ................................................................................................26

6.1.2. Water temperature .................................................................................................................28

6.1.3. Dissolved oxygen ...................................................................................................................29

6.1.4. Irrigation ................................................................................................................................30

6.1.5. Recreation .............................................................................................................................33

6.2. Literature review ...........................................................................................................................35

6.3. Lower Darling flow release and water quality event ........................................................................36

6.4. Summary statistics........................................................................................................................40

6.4.1. Total annual flow....................................................................................................................43

6.5. Risk assessment...........................................................................................................................43

7. Discussion...........................................................................................................................................45

7.1. Elevated levels of salinity ..............................................................................................................45

7.2. Elevated levels of suspended matter..............................................................................................47

7.3. Elevated levels of nutrients............................................................................................................49

7.4. Elevated levels of cyanobacteria....................................................................................................51

7.5. Water temperature outside natural ranges .....................................................................................52

7.6. Dissolved oxygen outside natural ranges .......................................................................................52

7.7. Elevated levels of pesticides and other contaminants .....................................................................54

7.8. pH outside natural ranges .............................................................................................................54

7.9. Elevated pathogen counts .............................................................................................................55

7.10. Knowledge gaps........................................................................................................................55

8. Conclusion ..........................................................................................................................................56

References ................................................................................................................................................58

Appendix A. Water quality monitoring site locations .....................................................................................64

Appendix B. Water quality index (WaQI) method..........................................................................................66

Appendix C. Literature Review ....................................................................................................................68

Appendix D. Water quality summary statistics..............................................................................................71

Appendix E. Draftsman plots and Box plots by site ......................................................................................78

Murray River at Indi Bridge......................................................................................................................79

Tooma River at Warbrook .......................................................................................................................81

Murray River at Jingellic ..........................................................................................................................83

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Murray River at Albury (Union Bridge)......................................................................................................85

Murray River downstream Yarrawonga Weir ............................................................................................87

Edward River at Deniliquin ......................................................................................................................89

Wakool River at Stoney Crossing.............................................................................................................91

Wakool River at Kyalite ...........................................................................................................................93

Murray River at Barham ..........................................................................................................................95

Murray River upstream Euston Weir ........................................................................................................97

Murray River at Merbein Pump Station.....................................................................................................99

Darling River at Weir 32 ........................................................................................................................101

Darling River at Burtundy ......................................................................................................................103

List of tables Table 1: Summary of major issues and causes of water quality degradation ....................................................i

Table 2: Water quality processes ..................................................................................................................3

Table 3: Water quality targets for water dependent ecosystems objective for all aquatic ecosystems ...............5

Table 4: Salinity targets for irrigation water ....................................................................................................7

Table 5: Blue-green algae targets for recreational water.................................................................................7

Table 6: Salinity targets for purposes of long term salinity planning in the Murray Lower Darling WRPA...........8

Table 7: List of routine water quality monitoring stations in the Murray Lower Darling WRPA .........................19

Table 8: List of Irrigation Infrastructure Operators and relevant continuous electrical conductivity monitoring

stations in the Murray Lower Darling WRPA ................................................................................................19

Table 9: List of selected blue-green algae monitoring stations in the Murray Lower Darling WRPA ................20

Table 10: List of continuous water temperature monitoring stations in the Upper Murray River WRPA ...........21

Table 11: List of continuous dissolved oxygen monitoring stations in the Murray Lower Darling River WRPA .22

Table 12: Water quality index scores for the Murray and Lower Darling WRPA 2010-2015 water quality data 26

Table 13: Water quality index scores for the Murray Lower Darling WRPA 2005-2015 continuous electrical

conductivity data ........................................................................................................................................31

Table 14: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 31 August ...........39

Table 15: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 7 September .......39

Table 16: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 12 September .....39



Table 19: Electrical conductivity profiles from Lock 10 and Darling River at Wentworth – 13 October .............40

Table 20: Sites with high and medium risk to the health of water dependent ecosystems from turbidity ..........44

Table 21: Sites with high and medium risk to the health of water dependent ecosystems from total phosphorus

..................................................................................................................................................................44

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Table 22: Sites with high and medium risk to the health of water dependent ecosystems from total nitrogen ..44

: Sites with high and medium risk to the health of water dependent ecosystems from dissolved oxygen

: Water quality summary statistics for the Murray Lower Darling WRPA 2007-2015 water quality data

Table 23: Sites with high and medium risk to the health of water dependent ecosystems from pH .................44

Table 24

..................................................................................................................................................................44

Table 25: Location of water quality monitoring stations in the Murray Lower Darling WRPA ...........................64

Table 26: Review of published literature ......................................................................................................68

Table 27

..................................................................................................................................................................71

Table 28: Electrical conductivity in the Darling River at Burtundy and Murray River at Lock 6 for purposes of

long term salinity planning...........................................................................................................................76

Table 29: Electrical conductivity in Edward and Wakool Rivers for purposes of long term salinity planning .....76

Table 30: Electrical conductivity in the mid Murray River for purposes of long term salinity planning ..............77

List of figures Figure 1: Flow diagram illustrating the components of the Murray Lower Darling surface water resource plan ..2

Figure 2: Water quality zones and water quality monitoring sites for the Murray Lower Darling WRPA .............4

Figure 3: Continuous water temperature monitoring sites in the Upper Murray River .....................................21

Figure 4: Continuous dissolved oxygen monitoring sites in the Murray River catchment ................................22

Figure 5: Conceptual diagram of the CSI process ........................................................................................24

Figure 6: Murray Lower Darling WRPA water quality index scores ................................................................27

Figure 7: Water temperature downstream of Hume Dam compared to estimated 20th and 80th percentile of

natural temperature ....................................................................................................................................28

Figure 8: Minimum daily water temperature in the Murray River upstream and downstream of Hume Dam.....29

Figure 9: Dissolved oxygen in the Darling River at Burtundy from 2012 to 2017 ............................................30

Figure 10: Dissolved oxygen in the mid Murray River and Edward-Wakool system from 2012 to 2017 ...........30

Figure 11: Mean daily electrical conductivity (µS/cm) at selected sites in the Murray valley from 2005 to 2015

..................................................................................................................................................................31

Figure 12: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Wakool River at

Stoney Crossing from 2007 to 2015 ............................................................................................................32

Figure 13: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Darling River at

Burtundy from 2005 to 2017 (red line indicates 833 µS/cm irrigation salinity target) .......................................33

Figure 14: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Murray River at Lock

6 from 2008 to 2017 (red line indicates 580 µS/cm flow target) .....................................................................33

Figure 15: Potentially toxic algal biovolume (mm3/L) at selected sites in the Murray River from January to July

2016 ..........................................................................................................................................................34

Figure 16: Harmful algal blooms at selected sites in the Edward Wakool River system from January to July

2016 ..........................................................................................................................................................35

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49

50


Figure 17: Electrical conductivity (µS/cm) in Lake Wetherell compared to inflows from the Darling River at

Wilcannia gauging stations .........................................................................................................................38

Figure : Continuous electrical conductivity (µS/cm) at Darling River gauging stations ................................38

Figure : Water quality data for water quality parameters by site ................................................................42

Figure : Annual flow (ML/year) at selected gauging stations......................................................................43

Figure : River styles recovery potential in the Murray and Lower Darling Rivers catchment........................48

Figure : Soil total nitrogen for the Murray and Lower Darling Rivers catchment..........................................50

Figure : Soil total phosphorus for the Murray and Lower Darling Rivers catchment ....................................50

Figure : Soil pH for the Murray and Lower Darling Rivers catchment .........................................................55

Figure : Draftsman plots for Murray River at Indi Bridge............................................................................79

Figure : Water quality data for Murray River at Indi Bridge ........................................................................80

Figure : Draftsman plots for Tooma River at Warbrook .............................................................................81

Figure : Water quality data for Tooma River at Warbrook .........................................................................82

Figure : Draftsman plots for Murray River at Jingellic................................................................................83

Figure : Water quality data for Murray River at Jingellic ............................................................................84

Figure : Draftsman plots for Murray River at Albury ..................................................................................85

Figure : Water quality data for Murray River at Albury...............................................................................86

Figure : Draftsman plots for Murray River downstream Yarrawonga Weir..................................................87

Figure : Water quality data for Murray River downstream Yarrawonga Weir ..............................................88

Figure : Draftsman plots for Edward River at Deniliquin ............................................................................89

Figure : Water quality data for Edward River at Deniliquin ........................................................................90

Figure : Draftsman plots for Wakool River at Stoney Crossing ..................................................................91

Figure : Water quality data for Wakool River at Stoney Crossing...............................................................92

Figure : Draftsman plots for Wakool River at Kyalite.................................................................................93

Figure : Water quality data for Wakool River at Kyalite .............................................................................94

Figure : Draftsman plots for Murray River at Barham ................................................................................95

Figure : Water quality data for Murray River at Barham ............................................................................96

Figure : Draftsman plots for Murray River upstream Euston Weir ..............................................................97

Figure : Water quality data for Murray River upstream Euston Weir ..........................................................98

Figure : Draftsman plots for Murray River at Merbein Pump Station ..........................................................99

Figure : Water quality data for Murray River at Merbein Pump Station.....................................................100

Figure : Draftsman plots for Darling River at Weir 32..............................................................................101

Figure : Water quality data for Darling River at Weir 32 ..........................................................................102

Figure : Draftsman plots for Darling River at Burtundy ............................................................................103

Figure : Water quality data for Darling River at Burtundy ........................................................................104

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1. Introduction

1.1. Purpose The Murray Darling Basin Plan (2012) is an instrument of the Commonwealth Water Act (2007). It provides the framework for long term integrated management of water resources of the Murray Darling Basin. The Basin Plan requires that water quality management plans (WQMP) are developed for all water resource areas in the Basin. Each WQMP will:

Establish water quality objectives and targets for freshwater dependent ecosystems, irrigation water and recreational purposes;

Identify key causes of water quality degradation;

Assess risks arising from water quality degradation, and

Identify measures that contribute to achieving water quality objectives.

This report provides an overview of the water quality condition of the Murray Lower Darling water resource plan area (WRPA) by comparing data to the Basin Plan water quality targets (Basin Plan 2012, Schedule 11). The Basin Plan water quality targets set out the appropriate water quality required for environmental, social, cultural and economic benefits in the Murray Darling Basin. Monitoring progress towards achieving the targets will identify trends and inform actions that address the causes of water quality decline. These targets have been used to assess existing water quality data, and to identify areas of risk to aquatic ecosystems, and recreational and irrigation use.

The report also outlines the factors influencing water quality in the region, specifically the likely causes of water quality degradation issues, as required by Chapter 10, Section 10.30 of the Basin Plan.

BASIN PLAN 10.30 Water quality management plan to identify key causes of water quality degradation. The water quality management plan must identify the causes or likely causes, of water quality degradation in the water resource plan area having regard to the key causes of water quality degradation identified in Part 2 of Chapter 9 and set out in Schedule 10.

The information in this report supports the development of the Murray Lower Darling WQMP. It provides the background and technical information to develop water, land and vegetation management measures to maintain or improve water quality in the Murray Lower Darling WRPA. Figure 1 is a flow diagram illustrating how this report supports other components of the surface water resource planning process.

NSW Department of Planning, Industry and Environment | INT18/36342 | 1


Water Resource Plan

Land and

Vegetation

Management

Develop,

implement and

evaluate best

practice land

and vegetation

management

practices to

increase

productivity

and

sustainability

of riverine

landscapes

Long Term

Watering Plan

Primary

mechanism

outlining

watering

requirements

for key

environmental

assets.

Guides the

use of

environmental

water over a

20 year period

Resource DescriptionDescription of water resource plan area to provide an understanding of the region and its resources

Risk assessmentIdentifies risks of not achieving Basin Plan

environmental, social and economic outcomes

and proposes strategies for mitigation

Status and issues paperSummarises the current condition of water

resources and issues to consider when

developing the Water Resource Plan

Salinity Technical

ReportTechnical information and analysis

to develop water and land

management measures that

protect or improve salinity.

Water Quality Technical

ReportTechnical information and analysis

to develop water and land

management measures that

protect or improve water quality

Water Quality Management PlanProvides a framework to protect, improve and

restore water quality and salinity that is fit for

purpose

Water Sharing PlanDescribes water rights, compliance with

sustainable diversion limits, water quality

management, environmental watering, and

risks to water resources meeting critical human

needs

Incident Response GuideDescribes how water resources will be managed

during an extreme event

Monitoring Evaluation and Reporting PlanMonitoring the effectiveness of measures for the purpose of adaptive management and reports progress

against requirements of Schedule 12 of the Basin Plan

Issues

Assessment

Report

Figure 1: Flow diagram illustrating the components of the Murray Lower Darling surface water resource plan

1.2. Context Water quality can be defined in terms of the physical, chemical and biological content of water and in terms of purpose and use. Water quality may be fit for one purpose, but not another. For example, water may be of good quality to irrigate crops, but may not support a healthy population of fish.

This report refers to water quality degradation, or poor water quality, as:

Elevated levels of nutrients, turbidity, blue-green algae, salinity, toxicants or pathogens, and

Water temperature, pH and dissolved oxygen outside of certain ranges.

Water quality is dynamic. The physical, chemical and biological content of water varies with time and location. Table 2 shows how water quality can be defined in three related, but slightly different ways.



Table 2: Water quality processes

Long term water quality Poor water quality event Ecosystem processes

This describes long-term average

trends over a period of months to

years. In this report, the water

quality parameters used are from

monthly measurements at a

selection of locations.

Major trends are reported in five

year periods. Indicator targets are

listed in Tables 3 to 6.

These refer to occurrences of

water quality issues for set

periods of time that are generally

not ongoing.

Examples may include a

potentially toxic algal bloom or

anoxic blackwater (low-oxygen)

event. While the occurrence of

these events may be short lived,

their effects can be long-term.

Water quality parameters are bound

up in fundamental ecological

functions of rivers and catchments.

These are less easy to define as

‘good’ or ‘bad’, and often involve complex interrelationships.

Examples may include the movement

of organic carbon from floodplains to

rivers to support productivity, or the

delivery of sediment from upstream

to downstream.

1.3. Catchment description The New South Wales Murray WRPA is bounded by the Murray River to the south, the Billabong Creek catchment (Murrumbidgee River WRPA) to the north and the Australian Alps to the east. The Murray River rises in the Australian Alps at 1 430 m above sea level. The catchment above Hume Dam is the major source of water for the Murray River. The total length of the Murray River is 2 530 km, of which 1 880 km of its length creates the border between NSW and Victoria, before flowing to the river mouth in South Australia. The natural flow regime is characterised by high winter/spring flows and low summer/autumn flows resulting from run-off derived from its alpine headwaters and associated tributaries. The five longest tributaries are the Mitta Mitta River, Kiewa River, Tooma River, Black Dog Creek and Swampy Plain River. The significant inter-valley diversions of both the Snowy-Tumut and Snowy-Murray Developments of the Snowy Mountains Hydroelectric Scheme impact on the Upper Murray River Water Source. This is a direct result of the operation of Murray 1 and Murray 2 Power Stations and their final storage dam, Khancoban Pondage.

Flows in the Murray River system are modified by a highly regulated weir system, water extraction and structures. Yarrawonga Weir is the point of the greatest diversion of water from the Murray River. The two main irrigation channels from Lake Mulwala are the Mulwala Canal, on the New South Wales side, and the Yarrawonga Main Channel, on the Victorian side. The Mulwala Canal has a discharge capacity of about 10 000 ML/day, and provides flows to the Edward and Wakool Rivers and numerous distributary streams and canals. Torrumbarry Weir diverts flows into Deniboota Canal in NSW and National Channel in Victoria, and Euston Weir regulates water for the Robinvale Irrigation District. The Murrumbidgee River flows into the Murray River upstream of Euston Weir.

Flows in the Lower Darling are regulated by releases from Menindee Lakes. There are two major river systems in the Lower Darling, the Darling River and the Great Darling Anabranch. The Darling River flows into Lock 10 on the Murray River at Wentworth.

There are two sites in the Murray Lower Darling WRPA listed as wetlands of international importance under the Ramsar Convention. The NSW Central Murray State Forests consist of three discrete but interrelated forest areas; the Millewa, Koondrook-Perricoota and Werai forests. Blue Lake in Kosciuszko National Park was listed under the Ramsar Convention in 1996. The Darling Anabranch Lakes are listed in the Directory of Important wetlands. The Living Murray icon sites within NSW include the Millewa Forest, Koondrook-Perricoota Forest, the eastern section of Chowilla floodplain and the River Murray Channel.

Land use in the Murray and Lower Darling catchment is largely grazing in the upper catchment with increased cultivation and irrigation with distance down the catchment. A detailed description of climate, land and water usage and water regulation infrastructures can be found in the Murray Lower Darling resource description report (DoIW 2018a).



1.4. Water quality targets The Basin Plan water quality targets set out the appropriate water quality required for environmental, social, cultural and economic benefits in the Murray Darling Basin. Monitoring progress towards achieving the targets will identify trends and inform actions that address the causes of water quality decline. The Basin Plan identifies water quality “target application zones” approximating lowland, upland and montane areas of the major river valleys. Lowland areas have an altitude of less than 200 m, upland areas fall between 200 and 700 m and montane areas have an altitude greater than 700 m. The boundaries of these zones are shown in Figure 2.

Two water-dependent ecosystems are described in the Basin Plan; Declared Ramsar wetlands (streams and rivers; lakes and wetlands) and Other water-dependent ecosystems (streams, rivers, lakes and wetlands). The assessment of water quality targets in this report is focused on Other water-dependent ecosystems, as there are currently no routine water quality monitoring programs undertaken in the Ramsar listed wetlands in the Murray Lower Darling WRPA. A revision of the current water quality monitoring program is to be undertaken to fill identified information gaps.

The Basin Plan water-dependent ecosystem targets for turbidity, total phosphorus, total nitrogen, dissolved oxygen and pH were developed following the methods outlined in the ANZECC Guidelines (2000). Water quality data for rivers and streams in ‘reference’ condition from each of the water quality zones were used to develop the target values for each zone (Tiller and Newall 2010). In zones where there were no reference sites, the appropriate default trigger value from the ANZECC Guidelines (2000) for slightly to moderately disturbed systems was used as the Basin Plan water quality target (Tiller and Newall 2010).

Figure 2: Water quality zones and water quality monitoring sites for the Murray Lower Darling WRPA



1.4.1.Assessment using Basin Plan water quality targets

The ANZECC Guidelines (2000) are currently under revision (Guideline Document 4: Australian and New Zealand Guidelines for Fresh and Marine Water Quality 2000) as part of the broader revision of the National Water Quality Management Strategy. It is anticipated that there will be no default trigger values in the revised guidelines for Basin States as it is expected that these states have developed regional water quality targets as part of other water planning processes. Basin States may choose to use the water quality targets of the Basin Plan in lieu of the default trigger values of the ANZECC Guidelines (2000) if local water quality guidelines are not available. Trigger values and management targets are conceptually different. A trigger value is a concentration below which there is a low risk of adverse effects and if exceeded indicates that some form of action should commence. Management targets are long term objectives used to assess whether an environmental value is being achieved or maintained.

An assessment of Basin Plan water quality targets in NSW (Mawhinney and Muschal 2015) identified targets in some zones and zone boundaries as being inappropriate. Perceived poor water quality at a monitoring site may be due to an inappropriate target, rather than excessive pollutants. In these cases, the Basin Plan targets should be revised in preference for location specific targets which consider local catchment conditions.

It is anticipated the revision of the National Water Quality Management Strategy will improve the advice about comparing results from individual monitoring sites against water quality targets, with more emphasis on catchment assessments and flow-dependant trigger values. The Basin Plan allows an alternate target to be specified in the WQMP under certain conditions. It is expected that the recommendation to develop specific targets will also be retained in the revised National Water Quality Management Strategy. There will be further discussion of water quality targets in the Murray Lower Darling WQMP.

1.4.2.Water quality targets for water-dependent ecosystems

The targets for water dependent ecosystems are to ensure water quality is sufficient to:

Protect and restore ecosystems;

To protect and restore ecosystem functions;

Ensure ecosystems are resilient to climate change, and

Maintain the ecological character of wetlands.

Turbidity, total phosphorus and total nitrogen annual medians in the Murray Lower Darling WRPA should be below the target values listed in Table 3. For dissolved oxygen and pH, the annual median should fall within the stated range. The toxicants targets are taken from the ANZECC water quality guidelines (2000) using the values for the protection of 95% of species. The 95% protection of species trigger values applies to typical, slightly to moderately disturbed systems.

Table 3: Water quality targets for water dependent ecosystems objective for all aquatic ecosystems

Water Quality

Zone

Ecosystem

Type

Turbidity

(NTU)

Total

Phosphorus

(µg/L)

Total

Nitrogen

(µg/L)

Dissolved

oxygen

(mg/L; or

% saturation)

pH Salinity Temperature

Toxicants

(must not

exceed

values in

3.4.1 of the

ANZECC

guidelines)

Water dependent ecosystems (not including Ramsar sites)

C6 (Mitta Mitta,

Upper Murray

Montane zone)

Streams, rivers,

lakes and

wetlands

5 25 150 >9 mg/L or

95-110% 6.4-7.7

End of valley

targets for

salinity in

Appendix 1 of

Schedule B to

the agreement

Between the

20th and 80th

percentile of

natural monthly

water

temperature

The

protection of

95% of

species

B6 (Kiewa,

Mitta Mitta,

Upper Murray,

Upland zone)

Streams, rivers,

lakes and

wetlands

5 30 350 >8.5 mg/L or

85-110% 6.4–7.7

cMum (Murray

Valley Central,

Streams, rivers,

lakes and

wetlands

15 40 500 >7.7 mg/L; or

90-110% 6.5–7.5



Upper Middle

zone)

cMI (Central

Murray Lower

zone)

Streams, rivers,

lakes and

wetlands

35 80 700 >8.0 mg/L or

90-110% 6.8-8.0

Dml (Darling

valley, Middle

Lower zone)

Streams, rivers,

lakes and

wetlands

50 50 500 85-110% 6.5-8.0

IM (Lower

Murray zone)

Streams, rivers,

lakes and

wetlands

50 100 1000 85-110% 6.5-9.0

Ramsar listed water dependent ecosystems

C6 (Mitta Mitta

Upper Murray

Montane zone)

Streams and

rivers 5 25 150

>9mg/L or 95-

110% 6.4-7.7

End of valley

targets for

salinity in

Appendix 1 of

Schedule B to

the agreement

Between the

20th and 80th

percentile of

natural monthly

water

temperature

The

protection of

99% of

species

Lakes and

wetlands 20 10 350 90–110% 6.5–8.0

B6 (Kiewa,

Mitta Mitta,

Upper Murray,

Upland zone)

Streams and

rivers 5 20 230

>8.5 mg/L or

85-110% 6.4–7.7

Lakes and

wetlands 20 10 350 90–110% 6.5–8.0

cMum (Murray

Valley Central,

Upper Middle

zone)

Streams and

rivers 15 40 500

>7.7 mg/L; or

90-110% 6.5–7.5

Lakes and

wetlands 20 10 350 90-110% 6.5-8.0

cMI (Central

Murray Lower

zone)

Streams and

rivers 35 80 700

>8.0 mg/L or

90-110% 6.8-8.0

Lakes and

wetlands 20 10 350 90-110% 6.5-8.0

Dml (Darling

valley, Middle

Lower zone)

Streams and

rivers 50 50 500 85-110% 6.5-8.0

Lakes and

wetlands 20 10 350 90-110% 6.5-8.0

IM (Lower

Murray zone)

Streams and

rivers 50 100 1000 85-110% 6.5-9.0

Lakes and

wetlands 20 10 350 90-110% 6.5-8.0

1.4.3.Water quality targets for raw water for treatment for human consumption

The target is to minimise the risk that raw water taken to be treated for human consumption results in adverse human health effects. The quality of raw water for treatment should also maintain palatability and odour ratings. The Public Health Act 2010 and the Public Health Regulation (2012) require drinking water suppliers to develop and adhere to a Drinking Water Management System (DWMS). The DWMS addresses the elements of the Framework for Management of Drinking Water Quality (Australian Drinking Water Guidelines (NHMRC and NRMMC, 2011)) and is a requirement of water suppliers operating licence (NSW Ministry of Health 2013). Water providers in the Murray Lower Darling WRPA include: Albury City Council, Balranald Shire Council, Berrigan Shire Council, Broken Hill City Council, Central Darling Shire Council, Federation Council, Greater Hume Shire Council, Murray River Council, Snowy Valleys Council and Wentworth Shire Council.



1.4.4.Water quality targets for irrigation water

The aim of the agriculture and irrigation target is that the quality of surface water, when used in accordance with the best irrigation and crop management practices and principles of ecologically sustainable development, does not result in crop yield loss or soil degradation. The target is for the electrical conductivity 95th percentile of each 10 year period that ends at the end of the water accounting period, not exceed 833 µS/cm. The target in Table 4 applies at sites where water is extracted by an irrigation infrastructure operator for the purpose of irrigation. In NSW, irrigation infrastructure operators are defined as a separate third party that holds a water access entitlement and delivers water to shareholders. These include NSW Irrigation Corporations, Private Irrigation Districts and Private Water Trusts. The development of a Sodium Adsorption Ratio (SAR) target is outside the scope of this document and will be determined in future reporting when data is available. The time series electrical conductivity data collected by the gauging station network was used to assess this target rather than monthly manual grab samples.

Table 4: Salinity targets for irrigation water

Water Quality Zones Ecosystem Type

Electrical

conductivity

(µS/cm)

Sodium adsorption

ratio

All Streams, rivers, lakes

and wetlands 833 undetermined

1.4.5.Water quality targets for recreational water

The primary aim of these targets is to protect the health of humans from threats posed by the recreational use of water. This includes a low level of risk to human health from water quality threats posed by exposure to blue-green algae (cyanobacteria) through ingestion, inhalation or contact during recreational use of water resources. The targets are based on Chapter 6 of the National Health and Medical Research Council Guidelines for Managing Risk in Recreational Water (NHMRC 2008). In addition, it is also a general target that cyanobacterial scums should not be consistently present. The recreational water targets are listed in Table 5.

Table 5: Blue-green algae targets for recreational water

Water Quality

Zone

Ecosystem

Type Guidelines

All Recreational

water bodies

10 µg/L total microcystins; or 50 000 cells/mL toxic Microcystis aeruginosa; or

biovolume equivalent of 4 mm3/L for the combined total of all cyanobacteria where

suitable for a known toxin producer is dominant in the total biovolume; or

primary contact. 10 mm3/L for total biovolume of all cyanobacterial material where known toxins are

not present; or

Cyanobacterial scums consistently present

1.4.6.Salinity targets for managing water flows

Electrical conductivity targets have not been described for each water quality zone of the Murray Darling Basin. Instead, the Murray Darling Basin End-of-Valley salinity targets, as described in Schedule B, Appendix 1 of the Commonwealth Water Act (2007), have been incorporated into the water quality targets. There are no End-of-Valley targets for the Murray Lower Darling WRPA. Section 9.14 (5)(c) of the Basin Plan lists salinity targets for managing water flows. The levels of salinity at the reporting sites set out in Table 6



should not be exceeded 95% of the time. The time series electrical conductivity data has been assessed against the targets in Table 6.

Table 6: Salinity targets for purposes of long term salinity planning in the Murray Lower Darling WRPA

Reporting site Target value (µS/cm)

Darling River downstream of Menindee Lakes at Burtundy 830

River Murray at Lock 6 (downstream of the NSW/South

Australian border)

580

2. Water quality parameters This report focuses on assessment of water quality parameters listed in the Basin Plan. These parameters represent general water quality condition and are most likely to demonstrate change over time from broad scale implementation of natural resource management.

2.1. Turbidity and suspended sediment Turbidity is a measure of water clarity. As light passes through water it is scattered by suspended material; the higher the scattering of light, the higher the turbidity. For example, after rain, water in rivers may appear brown due to scattering of light from high levels of suspended soils. Turbidity and the amount of total suspended solids are closely related in the Murray and Lower Darling catchments.

The amount of suspended sediment in water is generally related to the intensity of human activity in the catchment, such as land clearing, accelerated erosion from agricultural land, stream banks or channels and localised issues such as the dispersive nature of the soil and stock access. High turbidity is often associated with increased flow following storm events.

Increased turbidity can lead to reduction in light penetration and primary production. It can also lead to blooms of some harmful blue-green algae species as they are able to out compete other algal species for light in highly turbid conditions (Oliver et al. 2010). Increased suspended sediments can also have negative impacts on plants through smothering (Brookes 1986) and on fish, for example, by clogging gills (Bruton 1985). Suspended matter can also provide a mode of transport for pollutants, such as heavy metals, (Chapman et al. 1998), nutrients and pesticides (Mawhinney 1998) and bacteria (Wilkinson et al. 1995).

Turbidity should be measured immediately without altering the original sample conditions such as temperature and pH (APHA 1995). Field turbidity is more representative of instream conditions and should be used in preference to laboratory measurement (Buckland et al. 2008).



Declining stream morphology, gully

erosion, side wall cut and head migration

Elevated levels of

suspended matter

Poor soil conservation

practices

Volume and manner of water

release for storages

Wave wash from

boats

Inappropriate frequency timing and

location of cultivation

Overgrazing of catchments, grazing of

riverbank and floodplains

Carp

Rapid drawdown of

water

2.2. Nutrients Nutrients such as nitrogen and phosphorus are important for sustaining growth and productivity within rivers but at high concentrations can become an issue in freshwater ecosystems. In many circumstances the inputs of nutrients to rivers has increased due to human activities. This process is known as eutrophication (meaning well-nourished) (Smith et al. 1999).

Sources of nutrient contamination include discharge from sewage treatment works, farms and industry, and runoff from agricultural land and urban storm water (Smith et al. 2006). Nutrients can be dissolved, bound within sediments, or adsorbed onto suspended material (i.e. soil or organic matter). Increased nutrient concentration can cause issues including nuisance algal blooms (Anderson et al. 2002), dissolved oxygen depletion (Dodds 2006) or inversely supersaturated and toxic effects to aquatic organisms (e.g. ammonia) (Davis and Koop 2006). This document generally refers to total nitrogen or total phosphorus as a basic measure of all forms of these two elements.



Elevated levels of

nutrients

Fertilisers

Nutrients from water storages

Animal waste

Sewage and industrial discharge

Soil and organic matter

Atmospheric

deposition

2.3. Dissolved oxygen Dissolved oxygen in water is essential for supporting fish and aquatic animals. If oxygen levels rise too high or drop too low it places stress on animals and can be fatal (Boulton et al. 2014). Dissolved oxygen may be measured as either the concentration of oxygen in water (mg/L), or as a percentage of the maximum amount of oxygen that may dissolve in water (% saturation). Dissolved oxygen concentrations vary throughout the day and are generally lowest at night when plants and algae are not producing oxygen.

Dissolved oxygen levels drop when respiration (microbes and animals breathing oxygen) out paces oxygen replenishment by primary production (photosynthesis from aquatic plants and algae, and atmospheric adsorption). This process is called ecosystem metabolism. Factors that influence metabolism include the concentration of organic carbon and nutrient bioavailability, temperature, light penetration, turbidity and hydrology (Caffrey 2004; Young et al. 2008). The Basin Plan targets for dissolved oxygen include a lower and upper range. Maintaining dissolved oxygen levels within this range indicates that ecosystem metabolism is largely in equilibrium.

When there is a sudden input of bioavailable organic carbon and nutrients, for example when flood waters inundate an area with high levels of fresh leaf litter and flush this material back into the river, microbial respiration can increase rapidly causing oxygen levels to drop to very low concentrations. These are known as anoxic blackwater events (Whitworth et al. 2012). Alternatively, high nutrient inputs can lead to excessive aquatic plant growth resulting in very high oxygen levels or supersaturation.



High microbial respiration as a result of

organic matter loading

Dissolved oxygen

outside natural

ranges

Eutrophication and excessive

plant and algal growth

Oxygen depletion in standing pools

Release of low oxygen bottom waters

from dams and weirs

2.4. pH The pH is a measure of how acidic or basic water is. The pH ranges between 0 (very acidic) to 14 (very basic) with 7 being neutral. A pH outside of natural ranges can be harmful to plants and animals (Boulton et al. 2014). It influences the solubility and bioavailability of nutrients and carbon and the toxicity of pollutants (Closs et al. 2009). Very high or low pH can affect the taste of water, increase corrosion in pipes and pumps and reduce the effectiveness of drinking water treatment (WHO 2004).

The pH in water varies with soil type, geology and surface water and groundwater interactions. Human activities such as agricultural practices that expose acid sulphate soils and increase erosion may lead to decreased pH (Dent and Pons 1995). Eutrophication and excessive algal growth can lead to increases in pH (Boulton et al. 2014). Detrimental effects from pH on aquatic ecosystems are unlikely at the levels found across much of the Murray Darling Basin (Watson et al. 2009).

Eutrophication and excess plant

and algal growth

pH outside of

natural ranges

Agricultural practices that lead to

soil acidification

Urban runoff

Exposure to the air of soils containing

iron sulfide material

2.5. Water temperature and thermal pollution Water temperature influences many biological and ecosystem processes. Warmer temperatures can increase growth rates and metabolism of microbes, animals, plants and algae (Boulton et al. 2014; Kaushal et al. 2010). Temperature is also linked to spawning, breeding and migration patterns of many aquatic animals (Astles et al.



2003; Lessard and Hayes 2003). Higher temperatures can result in increased solubility of salts and decreased solubility of oxygen (Boulton et al. 2014).

Temperature is highly dynamic and varies at different time scales (e.g. seasonally and day/night). Human activities can have large impacts on temperature. Thermal water pollution can occur when dams stratify creating a cold bottom layer. If water is released from this bottom layer, it can lead to considerably colder water temperature than normal (Preece 2004). Thermal water pollution has had significant negative impacts on fish recruitment and can potentially influence ecosystem productivity and carbon cycling downstream of dams (Lugg and Copeland 2014; Webb et al. 2008).

The removal of riparian vegetation reduces shading, leading to increased water temperatures (Marsh et al. 2005; Rutherford et al. 2004). Other human activities such as discharge from power plants or warmer groundwater can also lead to increased river temperature (Lardicci et al. 1999). Climate change is also affecting river temperatures in the Murray Darling Basin (Pittock and Finlayson 2011).

Reduced flow

Thermal pollution

Water released from below

thermocline of large storages

Removal of shading riparian

vegetation

Climate change

2.6. Salinity Salinity is the presence of soluble salts in water. It is generally measured as electrical conductivity (the ability of dissolved salts to transmit an electric current). Increased salinity can have harmful effects on many plants and animals (James et al. 2003), effect drinking water supplies (WHO 2004) and cause damage and loss to cropping and horticulture sectors (Hillel 2000). The suitability of water for irrigation is often measured as a sodium adsorption ratio (SAR), which is a measure of the relative concentration of sodium, calcium and magnesium (Sposito and Mattigod 1977).

Increased electrical conductivity in rivers may be caused by the presence of salt in underlying soil, or bedrock released by weathering, salt deposited during past marine inundation of an area, or salt particles being carried over the land surface from the ocean. Australia’s arid climate provides insufficient rainfall to dilute the high levels of salt in the landscape. This has been further exacerbated by the increased mobilisation of salts by the use or discharge of saline groundwater to surface water, removal of deep-rooted native vegetation to be replaced with shallow-rooted crops or pastures and discharge of saline water from mining or industrial processes.

The initial stage of a flood is characterised by high electrical conductivity, often called a ‘first flush’. These appear as sharp spikes in the data followed by a rapid decline. As rainfall first starts to run off the landscape, it mobilises salts concentrated on the soil surface and washes them into the waterways. As flow increases, salts concentrated in the bottom of pools are also flushed out. Following this peak, electrical conductivity drops rapidly due to the dilution of salts by rainwater. The irrigation industry is more likely to experience difficulties with these high salinity spikes before impacts of any long term accumulation are realised. It is advisable for irrigators to let this first flush pass downstream before commencing to pump.



Saline surface and shallow groundwater

drainage from irrigated landElevated levels of

salinity

Irrigation with groundwater at locations

where highly saline upper aquifer water

drains to lower aquifer

Replacement of deep-rooted

vegetation with shallow-rooted

vegetation

De-watering of

saline groundwater

Reduction of in-stream flows

limiting dilution

Use of water with a high ratio of sodium

to calcium and magnesium for irrigation

Increased deep drainage below

irrigated agricultural land displacing

saline groundwater to surface water

Irrigation at high

salinity risk locations

Saline water discharges

2.7. Harmful algal blooms Most algae are safe and are a natural part of aquatic ecosystems. However, some types of blue-green algae (cyanobacteria) can produce hepatotoxins, neurotoxins and contact irritants. When these species occur in bloom proportions (harmful algal blooms) they pose a serious risk to human, animal and ecosystem health (Chorus and Bartram 1999). In addition to toxin production, algal blooms can produce taste and odour problems in water supplies and blockages in irrigation systems. Harmful algal blooms can occur when there are suitable conditions including high levels of nitrogen and phosphorus, warm water temperatures and sunny days, low turbidity and calm water conditions where water may stratify (Anderson et al. 2002; Hudnell 2008). Blue-green algal blooms are normally associated with lakes and reservoirs, but do occur in rivers when conditions are favourable.

Harmful algal

blooms

Stratification

Water with little or no flow

Nutrients

Seeding from upstream

High temperatures

Sunlight



2.8. Toxicants Toxicants refer to chemical contaminants that have the potential to be toxic at certain concentrations. These include metals, inorganic and organic toxicants (Warne 2002; Warne et al. 2014). Toxicants can have public health impacts and induce stress and fatalities in plants and animals (Heugens et al. 2001; Newman 2009). Toxicants enter water from a range of human activities including agriculture, industry and mining, and can also enter surface waters naturally through groundwater connectivity.

Spray drift, vapour transport and runoff are the main pathways for pesticide transport into river systems (Mawhinney 1998, Raupach et al. 2001). Spray drift and vapour can both contribute low level but almost continuous inputs to the riverine ecosystem during the peak spraying season. The likelihood of pesticide drift is influenced by weather conditions, the method of application, equipment used and crop structure. Runoff tends to provide occasional high concentrations of pesticide contamination. Pesticides in runoff can be dissolved in the water, bound within sediments or adsorbed on to suspended particles.

Inappropriate disposal of pesticides

and toxicants

Elevated levels of

toxicants

Erosion of contaminated land

Carp

Leaching of toxicants

into groundwater

Increased deep drainage below

irrigated agricultural land displacing

saline groundwater to surface water

Toxicants in sewage

Runoff of pesticides and

other toxicants

2.9. Pathogens Bacteria and microorganisms occur naturally in rivers. Certain species that have the potential to elicit disease symptoms are referred to as pathogens. In certain concentrations, pathogens can have negative impacts on public health (Prüss 1998; WHO 2004), aquatic animals (Gozlan et al. 2006), stock watering (LeJeune et al. 2001) and inhibit the use of water for irrigation (Steele and Odumeru 2004).

Human activities can increase the potential risk from pathogens, including discharge of human and animal waste and sewage, and access of stock and animals to rivers and water supplies (Ferguson et al. 1996; Fong and Lipp 2005; Hubbard et al. 2004). Deal and Wood (1998) reported high levels of faecal coliforms were generally reported in spring and summer whilst autumn and winter had lower levels. The sources of the Escherichia coli in river samples were identified as both animal and human in origin. Current monitoring and knowledge of the presence of pathogen issues in the Murray and Lower Darling catchments is limited.

It is expected that increased runoff will result in increased faecal coliforms, as material such as soil and faecal matter is washed into waterways. Additionally, periods of low rainfall, low flow, and warm water temperatures provide appropriate conditions for faecal coliforms to multiply (Deal 1997).



Elevated levels of

pathogens

Major waterbird breeding events

Human and animal

waste

Sewage and

wastewater discharges

3. Water access rules and flow management in the Murray Lower Darling WRPA

In parts of the catchment where flows are unregulated, there are very limited opportunities to manage water quality through flow management. Under the water sharing plan for the New South Wales Murray unregulated and alluvial water sources (2011), pumping is not permitted from natural pools when the water level in the pool is lower than its ‘full capacity’. Full capacity can be approximated by the pool water level at the point where there is no visible flow out of that pool. The Cease to Pump rule ensures that additional pressure is not placed on pools by extracting water when the waterway has stopped flowing. During low flows, as pools contract, water quality can deteriorate, algal blooms occur, dissolved oxygen levels decline and fauna compete for the reducing food supplies.

Unregulated streams in western NSW experience long periods of no flow, interspersed with rare flows of varying magnitude. The water sharing plan for the Lower Murray-Darling unregulated and alluvial water sources (2012) focuses on water management in pools and lagoons.

In the regulated systems downstream of Hume Dam and Menindee Lakes, there is more scope to utilise flow rules and environmental flows to benefit water quality. In the water sharing plan for the NSW Murray and Lower Darling regulated rivers water sources (2016), there are rules for both planned and adaptive environmental water. The following environmental water rules have been included in the NSW Murray and Lower Darling water sharing plan.

Barmah-Millewa Environmental Water Allowance (Barmah-Millewa Allowance) – The management of this allowance is a shared NSW and Victorian responsibility. Releases from this account must be used to provide environmentally beneficial outcomes for Barmah-Millewa Forest in accordance with relevant interstate agreements. The volume credited to the Allowance depends on a variety of factors, which are detailed in the NSW Murray and Lower Darling regulated rivers water sharing plan. Water may be carried over from one year to the next up to a maximum volume of 350 000 ML. Releases are made based on advice from the Murray Lower Darling Environmental Water Advisory Group.

Barmah-Millewa Overdraw Environmental Water Allowance (Barmah-Millewa Overdraw) – A volume of up to 50 000 ML is credited to the account when there are sufficient water reserves available without constraining available water determinations. Releases must be used to provide environmentally beneficial outcomes for the Barmah-Millewa Forest. Water may be carried over from one water year to the next, provided the volume does not exceed 50 000 ML. As for the Barmah-Millewa Allowance, releases are made based on advice from the Murray Lower Darling Environmental Water Advisory Group.



NSW Murray regulated river water source additional environmental water allowance (Murray Additional Allowance) – The method for calculating the volume credited to the account is detailed in the water sharing plan. Water may be released from this account for any purpose consistent with environmental objectives listed in the plan, including:

Maintain and enhance the ecological condition and their water dependent ecosystems;

Maintain and enhance downstream processes and habitats, and

Maintain and enhance water quality.

Environmental water allowance for the Lower Darling Water Source (Lower Darling Allowance) – The volume of water credited to the Lower Darling Allowance is 30 000 ML, less any release that has resulted in a loss of total water volume available under the accounting rules applying to interstate water sharing in the Murray and Lower Darling River. The volume credited is zero if the volume stored in Menindee Lakes is less than 480 000 ML, or if the volume has not risen above 640 000 ML since the volume stored, last fell below 480 000 ML. Releases from the Lower Darling Allowance may be made whenever a high blue-green algae alert is announced. The release rate must be less than 2 000 ML/day during May to October and 5 000 ML/day from November to April, or at a lower rate determined by the Minister.

Minimum flows from Hume Dam - Minimum flows from combined resources are to be maintained out of Hume Dam to ensure that downstream diversion needs are met, as well as for environmental maintenance and water quality purposes. The minimum flows are currently:

Minimum flows downstream of Hume Dam and upstream of the Kiewa River are 600 ML/day, and

Minimum flows downstream of Hume Dam at Doctors Point are 1 200 ML/day.

Minimum flows downstream of the Curlwaa pumps on the Murray - Minimum flows from combined resources are to be maintained downstream of the Curlwaa Irrigation District pumps on the Murray River during summer, to ensure that downstream diversion needs are met, as well as for environmental maintenance and water quality purposes. The recommended minimum flow is 1 200 ML/day during summer. The rates may be reduced below their minimum recommended flows according to conditions in the plan.

Flows in the Murray River at the South Australian border – A total contribution of 1 850 GL per annum is provided to the South Australian border as per the Murray Darling Basin Agreement. South Australia is also entitled to additional water to mitigate the impacts of surface water salinity. The delivery of this water to the border provides water quality benefits to the Murray River.

Long-term extraction limits – The Murray Lower Darling plan establishes a long-term extraction limit and rules for adjustment of the maximum amount of water that may be made available. All water above the plan extraction limit is to be used for the environment, and preserved for the maintenance of basic environmental health. Maintaining base flow is important to slow the decline in water quality by preventing pools from stratifying and stagnating.

Supplementary flow access rules - There are restrictions on extractions under supplementary water access licences. Holders of these licences are able to extract water during announced periods as a result of high tributary inflows, when flows exceed those required to meet other obligations and environmental needs. These restrictions are in place to:

Preserve a significant proportion of natural tributary flows for river health;

Protect important rises in water levels;

Maintain floodplain and wetland inundation, and

Maintain natural flow variability.

Rates of rise and fall – Releasing large volumes water as a block, with very steep rising and falling limbs, has the potential to pose threats to the Murray River through bank slumping and bank erosion. Rates of water level rise and fall, rates for drawdown for weir pools, rivers streams and waterways are listed in the plan to minimise river bank degradation.

The Commonwealth Environmental Water Office (CEWO) has environmental surface water entitlement in NSW, with additional water held in Victoria and South Australia that must be managed to protect or restore



environmental assets. The CEWO water must also be managed in accordance with the Basin Plan and the Basin Watering Strategy.

The NSW Office of Environment and Heritage (OEH) holds environmental water which was acquired under the Riverbank Program or Wetlands Recovery Program, either through water efficiency works or by purchase of entitlement.

It is not the intent of the Water Quality Management Plan to propose the use of environmental water to address water quality issues. However, the release of environmental water for its designated purpose, will provide water quality benefits for the Murray and Lower Darling Rivers, such as breaking up stratification in pools, diluting salts, mobilising dissolved organic carbon and making conditions less favourable for harmful algal bloom development. Holders of environmental water in their independent decision making, must 'have regard' to dissolved oxygen, salinity and recreational water quality when making decisions about the use of environmental water.

Environmental water is to be managed in accordance with the Long Term Watering Plan (LTWP), Basin Watering Strategy and Annual Basin Watering Priorities. In relation to water quality, the draft Murray and Lower Darling LTWP recognises water being of a quality unsuitable for use, as a risk to achieving environmental outcomes. Issues identified include poor water quality in terms of nutrients, dissolved oxygen and salinity, blue-green algae, chemical contaminants and cold water pollution.

There are opportunities to adjust the way water is delivered from Hume Dam to provide additional water quality and environmental benefits to the aquatic ecosystem. Mimicking a natural flood event by maintaining natural flow variability and natural rates of change in water levels, with more gradual rising and falling limbs, can help reduce bank slumping. Increased water levels can inundate lower benches, flushing carbon into the system providing fuel to stimulate riverine food webs. High flow velocities can also scour silt and biofilms from rocks and logs in the river, resetting biofilm development and improving habitat quality.

The trade of water entitlement is another potential rule to manage risks to water quality. Trading entitlement out of an over allocated water source or away from a potentially sensitive area, could have long term benefits by assisting in mitigating the impact on instream values via reduced levels of extraction. Similarly, the trade of held environmental water into a stressed water source could provide benefits to water quality. Water trade has not been identified in this report as an immediate mitigation measure, as there is no certainty of where, when, or if it may occur.

4. NSW Salt Interception Schemes Salt interception schemes (SIS) have been constructed as a key component of the Basin Salinity Management Strategy under a joint works and measures program, encompassing a total of 19 schemes within the Murray-Darling Basin. The Salinity Management Strategy was developed to manage the problems of river salinity, waterlogging and land salinisation in the Basin. The schemes are constructed at ‘high risk’ river reaches, where saline groundwater discharges from the alluvial sediments of the floodplain, into the river. The primary purpose of the schemes is to reduce groundwater pressures immediately adjacent to the river by extracting and redirecting saline groundwater to disposal lakes located some distance from the river. In most cases, a bore and pump system extracts the groundwater, and pumps it to salt disposal basins, where a significant portion of the water is evaporated, leaving a concentrated brine to strategically seep back into the groundwater system at very low rates, or the salt is harvested.

Investigations have shown significant salt load inflows or ‘hot spots’ occur in two localised areas: from Mallee Cliffs to Psyche Bend, and from Lock 11 to Merbein Common. There are two salt interception schemes in the Murray Lower Darling WRPA. These include the Buronga SIS and Mallee Cliffs SIS.

Operating protocols are in place for each SIS, relating to in-stream flows. Flows above a threshold generally dictate the cessation of a scheme’s operation, due to the hydraulic pressure preventing groundwater flow into the river.



4.1. Buronga SIS Investigations undertaken in the 1970s identified groundwater movement around the Mildura Weir as a major contributor to the salt load in the Murray River immediately downstream of the weir. The main mechanism for saline groundwater seepage to the river is the up-welling of deeper saline groundwater in response to the vertical hydraulic pressure resulting from the head difference between the upstream and downstream river levels at the weir. The salinity problem is further exacerbated by groundwater mounding under nearby irrigation areas at Mildura-Merbein, Buronga and Coomealla (AWE 2011). These activities have increased the pressures in the Parilla Sands aquifer system, resulting in the displacement of saline groundwater from that aquifer into the Murray River on the downstream side of the weir, over a reach of approximately 3.5 km.

A series of eight groundwater bores with submersible pumps were installed along the section of the Murray River both upstream and downstream of Lock 11, where the saline water is believed to be entering the river. The submersible pumps are located in the deeper Parilla Sands aquifer. Saline water is pumped from this aquifer to lower the pressure that is driving the saline water into the river. By lowering the pressure in the aquifer, the pressure gradient is reversed away from the river. The intercepted saline water is pumped approximately seven kilometres to the Mourquong disposal complex.

The Buronga SIS intercepts the saline groundwater seepage, preventing around 17 500 tonnes of salt from entering the Murray River annually. The salinity of the groundwater being pumped is around 65 000 µS/cm. It is estimated that the interception of saline water by the Buronga SIS will result in a reduction in river salinity of 6.7 µS/cm in the Murray River at Morgan, South Australia. The Buronga scheme, together with the companion Mildura-Merbein scheme located in Victoria, contribute a combined benefit of approximately 14 µS/cm at Morgan.

4.2. Mallee Cliffs SIS Mallee Cliffs SIS was commissioned in 1994 and comprises seven production bores designed to intercept regional groundwater flow and pump it to a disposal basin located 13 km north east of the SIS. The Mallee Cliffs disposal basin has a number of sections, where water is progressively concentrated and ultimately, to a brine storage area. Regional groundwater flow is concentrated at Mallee Cliffs due to the connection between the Parilla Sands and Monoman Formation (AWE 2009). The interception strategy of the scheme is to pump saline groundwater from the Parilla Sands aquifer before it discharges to the Monoman Formation and then to the river. Bores are located on both the floodplain and highland. Head pressures in the Parilla Sands aquifer have been found to be affected regionally by river level fluctuations, rainfall variability, and by operation of the scheme. Each affect is significant in terms of scheme operation and targets (AWE 2009).

The Mallee Cliffs SIS has a maximum pumping capacity of 14 ML/day, but is inoperative during river flows of greater than 20 000 ML/day. The scheme reduces the average salinity at Morgan by an estimated 13 µS/cm. NSW has developed a Responsive Management Monitoring Plan for Mallee Cliffs SIS. Rather than the scheme operating full-time, it is proposed to allow in-river conditions and the salinity risk outlook, guide the level of operation.

5. Methods

5.1. Site selection and monitoring The water quality data used in this report were compiled from 14 routine water quality monitoring stations located within the Murray Lower Darling WRPA. The data were collected on a monthly basis for two monitoring programs, with the data for three sites collected for the Murray Darling Basin Authority (MDBA) and 11 sites for the State Water Quality Assessment and Monitoring Program (SWAMP). The MDBA water quality monitoring program was established in the early 1990’s as a coordinated catchment based water quality program. The aim is to provide long-term quality assured data to describe the baseline condition of the river systems and identify any emerging issues. SWAMP is responsible for collecting, analysing and reporting the ambient water quality condition of rivers in NSW. The program in its current form commenced in November 2007 replacing



numerous regionally based water quality monitoring programs. The data set used in this report covers a five year period from July 2010 to June 2015. A five year time period was chosen as it is consistent with the Basin Plan (Schedule 12) five yearly review against water quality targets. There is only two years of water quality data for the Murray River at Lock 8. Monitoring commenced at this site in July 2013 in response to the identification of a water quality data gap in the Lower Murray zone.

A full station list is given in Table 7 and the location of these sites in relation to the Basin Plan water quality zones is shown in Figure 2. The coordinates for all monitoring sites are listed in Appendix A.

Table 7: List of routine water quality monitoring stations in the Murray Lower Darling WRPA

Basin Plan WQ zone Station Number

Station Name

B6 401556 Murray River at Indi Bridge

B6 401003 Tooma River at Warbrook

B6 401201 Murray River at Jingellic

cMum 409001 Murray River at Albury (Union Bridge)

cMum 409025 Murray River downstream Yarrawonga Weir

cMum 409003 Edward River at Deniliquin

cMum 409013 Wakool River at Stoney Crossing

cMum 409034 Wakool River at Kyalite

cMum 409005 Murray River at Barham

cMl 414209 Murray River upstream Euston Weir

cMl 414206 Murray River at Merbein Pump Station

Dml 425012 Darling River at Menindee Weir 32

Dml 425007 Darling River at Burtundy

lM 4261001 Murray River at Lock 8

There are 43 continuous electrical conductivity sites monitored by NSW in the Murray Lower Darling WRPA, with additional sites monitored by the Victorian state government. These are located at existing river gauging stations and take electrical conductivity readings every 15 minutes. All NSW continuous electrical conductivity data is stored in the Hydstra database. The data from stations located close to the offtakes of irrigation infrastructure operators have been assessed against the electrical conductivity target. These sites are listed in Table 8.

Table 8: List of Irrigation Infrastructure Operators and relevant continuous electrical conductivity monitoring stations in the Murray Lower Darling WRPA

Irrigation Operators Offtake location Electrical conductivity monitoring

station

Murray Irrigation Limited Mulwala Canal offtake from Murray River at Lake

Mulwala (Yarrawonga Weir)

Wakool Canal Offtake from Colligen Creek via the

Edward River

409025 Murray River downstream

Yarrawonga Weir

409023 Edward River downstream Stevens

Weir

Western Murray Irrigation

limited

Buronga pumping station on Murray River

Curlwaa pumping station on Murray River

Coomealla pumping station on Murray River

414216 Murray River downstream Mildura

Weir (VIC)

414217 Murray River at Curlwaa (VIC)



Moira Private Irrigation District Murray River upstream of Barmah. Diversion

channel at Moira Lake.

409215 Murray River at Barmah (VIC)

West Corurgan Private

Irrigation District

West Corurgan Canal offtake from the Murray

River between Corowa and Lake Mulwala

409002 Murray River at Corowa

Bama Irrigation Trust Murray River near Moama 409215 Murray River at Barmah (VIC)

Bringan Irrigation Trust Murray River near Barham 409005 Murray River at Barham

Bullatale Creek Waters Trust Murray River west of Tocumwal 409202 Murray River at Tocumwal (VIC)

Bungunyah Koraleigh

Irrigation Trust

Murray River near Koraleigh, upstream of

Tooleybuck

409204 Murray River at Swan Hill (VIC)

Glenview Irrigation Trust Murray River near Barham 409005 Murray River at Barham

Goodnight Irrigation Trust Murray River near Goodnight, downstream of

Tooleybuck and upstream of Wakool junction

409204 Murray River at Swan Hill (VIC)

Pomona Irrigation Trust

(Pomona Water)

Darling River upstream of Wentworth. Located in

the Lock 10 weir pool.

425017 Darling River at Wentworth (VIC)

West Cadell Irrigation Trust Murray River near Moama 409215 Murray River at Barmah (VIC)

There is an extensive blue-green algae monitoring program in the Murray Lower Darling WRPA with approximately 140 sites, including rivers, diversion channels, town water supplies, lakes and major storages. Water samples are collected by government agencies and industry groups, including WaterNSW, Goulburn Murray Water, Lower Murray Water, North East Water, Goulburn Valley W ater and numerous councils. Samples are collected more frequently in summer when there is an increased risk of algal blooms developing. Data from 14 sites has been assessed in this report. A list of the selected sites is in Table 9.

Table 9: List of selected blue-green algae monitoring stations in the Murray Lower Darling WRPA

Station Number Station Name

409001 Murray River at Albury (Union Bridge)

409026 Mulwala Canal at Offtake

409025 Murray River downstream of Yarrawonga Weir

409202 Murray River at Tocumwal

40910089 Murray River at Picnic Point

40910087 Murray River at Moama (Echuca)

409005 Murray River at Barham

41310021 Murray River at Mount Dispersion

409003 Edward River at Deniliquin

40910090 Edward River at Old Morago Road

409014 Edward River at Moulamein

409015 Gulpa Creek at Mathoura

409045 Wakool River at Wakool-Barham Road

409034 Wakool River at Kyalite

Water temperature data is collected at all routine water quality monitoring sites, however as it is collected monthly, it does not give an indication of diurnal variation or detect cold water impacts. Continuous water



temperature data is collected at 43 sites in the Murray Lower Darling WRPA by NSW agencies. Additional sites are monitored by Victoria. All these sites have permanent sensors installed at gauging stations. A list of sites in the upper Murray in close proximity to Hume Dam is given in Table 10 and the location of these sites is shown in Figure 3.

Table 10: List of continuous water temperature monitoring stations in the Upper Murray River WRPA

Station Number

Station Name

401012 Murray River at Biggara

401013 Jingellic Creek at Jingellic

401201A Murray River at Jingellic

409016 Murray River at Heywooods

409017 Murray River at Doctors Point

409001 Murray River at Albury (Union Bridge)

409037 Murray River at Howlong

409002 Murray River at Corrowa

409025 Murray River downstream Yarrawonga Weir

Map produced by NSW Industry I Lands & Water 10 October 2018

GF Water tempertaure monitoring sites

! Towns

Rivers

Murray Lower Darling Boundary

Data Sources:

NSW Industry I Lands & Water I Water.

Office of Environment and Heritage.

Murray Darling Basin Authority.

Geoscience Australia.0 20 40 60 80

kilometres

±

!

!

!

GF

GF

GF

GFGF

GF

GFGFGF

Murray

River atBiggara

Jingellic

Creek atJingellic

Murray

River atJingellic

Murray

River d/sHume DamMurray River

at DoctorsPoint

Murray

River atAlbury

Murray

River atHowlong

Murray

River atCorowa

Murray River d/s

Yarrawonga Weir

JING

ELLIC

CR

EE

K TOOMA

RIVER

MURRAYRIVER

LAKE

HUME

LAKE

MULWALA

KHANCOBAN

MULWALA

TUMBARUMBA

MURRAY AND LOWER DARLING WATER RESOURCE PLAN AREA- WATER TEMPERATURE MONITORING SITES

Mur

ray

Darli

ng

Ba

sin

Figure 3: Continuous water temperature monitoring sites in the Upper Murray River

The Murray Lower Darling is the only WRPA in NSW with an extensive continuous dissolved oxygen monitoring network. There are currently 11 sites in the Murray River catchment and one on the Lower Darling



(Table 11). The location of the dissolved oxygen monitoring sites in the Murray catchment is shown in Figure 4.

Table 11: List of continuous dissolved oxygen monitoring stations in the Murray Lower Darling River WRPA

Station Number

Station Name

409005 Murray River at Barham

409047 Edward River at Toonalook

409003 Edward River at Deniliquin

409014 Edward River at Moulamein

409062 Wakool River at Gee Gee Bridge

409013 Wakool River at Stoney Crossing

409048 Niemur River at Barham – Moulamein Road

409086 Niemur River at Mallan School

409044 Little Merran Creek at Franklins Bridge

409036 Merran Creek upstream Wakool River

409111 Barber Creek at Sandy Bridge Road

425007 Darling River at Burtundy

Map produced by NSW Industry I Lands & Water 10 October 2018

GF Dissolved oxygen monitoring sites

! Towns


Regulated Rivers

Data Sources:




Geoscience Australia.0 20 40 60 80

kilometres

±

!

!

!

!

!

GF GF

GF

GF

GF

GF

GF

GF

GF

GF

GF

Murray

River at

Barham

Edward

River at

Toonalook

Edward

River at

Deniliquin

Edward

River at

Moulamein

Wakool River at

Gee Gee Bridge

Wakool River

at Stoney

Crossing

Niemur River

at Barham –

Moulamein Road

Niemur River at

Mallan School

Little Merran Creek at

Franklins Bridge

Merran

Creek u/s

Wakool River Junction

Barber Creek at

Sandy Bridge Road

LAKE

MULWALA

BARHAM

SWAN

HILL

MOAMA

MULWALA

DENILIQUIN

MURRAY AND LOWER DARLING WATER RESOURCE PLAN AREA- DISSOLVED OXYGEN MONITORING SITES

Mur

ray

Darli

ng

Ba

sin

Figure 4: Continuous dissolved oxygen monitoring sites in the Murray River catchment



5.2. Water quality index (WaQI) A water quality index (WaQI) is an important tool to communicate and report water quality condition. It conveys information that is complex and on different scales (e.g. 75% saturation dissolved oxygen, 50 µg/L total phosphorus) to a common score and rating.

A literature review was conducted in 2015 to understand the different approaches and techniques for calculating and using water quality indexes globally. A method based on a modified Canadian Council of Ministers of the Environment (CCME) water quality index (Lumb et al. 2006) was then defined, that incorporated both frequency and exceedance of water quality targets. The method scales five years of data into a single number between 1 and 100 which corresponds to four categories: poor, fair, good and excellent. It is applied to both individual parameters and parameters combined to provide an overall score (Appendix B).

For New South Wales WQMP, the WaQI is calculated for each water quality parameter individually and as an overall integrated index. It includes total nitrogen, total phosphorus, turbidity, dissolved oxygen and pH. There is no weighting of individual parameters. It is based on the exceedance of water quality targets as prescribed in Schedule 11 of The Basin Plan. Where data is available, temperature, salinity and blue-green algae have also been scored as individual parameters.

The outcome provides a number between 1 and 100, and is categorised according to the following water quality rating.

5.3. Catchment stressor identification The Catchment Stressor Identification process (CSI) (Figure 5) helps describe the status, issues and potential causes of water quality degradation. The process uses an eco-epidemiological approach (Cormier 2006), and is broadly related to the approach developed by Cormier et al. (2003) for water quality planning in North America for the United States Environmental Protection Agency (USEPA). It identifies issues and causes based on the idea of abductive inference that is; considering possible causes of water quality degradation, weighing evidence and putting forward factors likely contributing to water quality degradation. Once the water quality degradation issues are defined, evidence is gathered and weighed before conclusions on probable causes synthesised.

The CSI process is intended to be iterative and involves conceptual mapping, data evaluation, literature reviews, GIS mapping and input of local and expert knowledge. The process consists of a standard set of procedures and outputs. The final output expresses what water quality degradation is present and the likely cause, using narrative, figures and maps.



Figure 5: Conceptual diagram of the CSI process

5.3.1.Conceptual mapping

Conceptual models are a useful step in mapping out possible causes of water quality degradation. They help define the scope of possible causes of water quality degradation and show interlinkages between both causes of degradation and between water quality parameters. A standard conceptual diagram for overall water quality and each parameter has been created based primarily on Schedule 10 of the Basin Plan. These standard models will then be revised for each parameter in each WRP area during the CSI process.

5.3.2.Literature review

A review of both published and grey literature has been undertaken for the Murray Lower Daring WRPA. Published literature was reviewed using a standardised approach through the Web of Science database. Grey literature was reviewed in an informal manner through web searches.

5.3.3.Summary statistics

The data used for this and the following analysis is primarily from the State Water Quality Assessment and Monitoring Program (SWAMP). Summary statistics of available data for each parameter in a WRP area will be defined. These include basic statistics such as range (minimum, maximum), central tendency (mean, median) and variability (standard deviation, interquartile range, coefficient of variation). These statistics help define basic patterns of water quality degradation.

5.3.4.Data analysis

Analysing water quality data is a crucial step in diagnosing issues and their causes. Basic analysis involved examining relationships between parameters, temperature and season, location and hydrology. Data analysis is used to help understand the nature of ecological problems, their interdependencies, seasonal variances, relationship to flow regimes and spatial relationships. Data analysis was based on routine sampling conducted between 2010 and 2015.

5.3.5.Spatial and GIS

Existing spatial information relevant to the causes of water quality degradation for each parameter has been compiled into ArcGIS geodatabases. Initial maps have been produced with relevant spatial information and land use are determined through the CSI process for each WRP area. The spatial information may be refined during the CSI process.



5.3.6.Local and expert knowledge

For each WRP area, meetings were held with the technical working group comprised of representatives from partner agencies and other invited experts. These meetings facilitated input of local knowledge and expert opinion to the WQMP. In general, these meetings occurred on a one-on-one or organisational basis. This approach was chosen to allow more freedom for people to speak and explore ideas. Information from these meetings was used to refine the scope of water quality degradation, conceptual diagrams, GIS mapping, and to guide further exploration. They also help define conclusions reached for the causes of water quality degradation and most relevant and fit-for-purpose information to include in this report and the WQMP.

5.4. Murray Lower Darling WRPA Risk Assessment Risk assessments are the first steps in the development of a water resource plan for each surface water and groundwater planning area in the Murray Darling Basin. Risk assessments and associated water resource plans must be prepared having regard to current and future risks to the condition and continued availability of water resources in a water resource plan area, and outline strategies to address those risks.

The risk assessment approach compiles the best available information to highlight the range of potential risks that may be present. Where a risk is highlighted as medium or high, it does not necessarily imply that existing rules in the water sharing plan require change or are inadequate, but rather, that further detailed investigation may be required. The risk assessment also highlights where existing plan rules may already be mitigating the risk.

The risk to the health of water dependent ecosystems was assessed by identifying the risk, quantifying the impact based on instream values (consequence) and determining the probability of that consequence occurring (likelihood).

The consequence of poor water quality was determined using the HEVAE (High Ecological Value Aquatic Ecosystems) instream value. For each monitoring station, a reach was defined as 25 km upstream and downstream of the site. This was chosen as a conservative estimate of the spatial representativeness of water quality data and movement of instream biota within the river channel. The consequence decision support tree was then used to define the final consequence score using the HEVAE instream values within each reach area. For detailed description of the risk assessment process and outputs, refer to the Risk Assessment for the Murray Lower Darling Water Resource Plan Area (SW8) (DoIW 2018b).

The calculation method for the likelihood scores varied between water quality attributes. The likelihood scores for total nitrogen, total phosphorus, dissolved oxygen, pH and turbidity were the frequency that the Basin Plan water quality target was exceeded, based on monthly sampling data for the five year period, 2010 to 2015.

Continuous electrical conductivity data, rather than discrete monthly data, was used to assess risks from poor salinity. In the NSW Murray and Lower Darling Rivers, there are no End-of-Valley salinity targets. For this reason, the default ANZECC guideline for lowland slightly disturbed ecosystem value of 300 µS/cm was used to assess the suitability for water dependent ecosystems. The likelihood of water being unsuitable for irrigation was calculated using the frequency that the 95th percentile of the daily mean electrical conductivity exceeded the Basin Plan irrigation infrastructure operator target of 833 µS/cm for the 10 year period from 2005 to 2015.

Water temperature risk was based on the presence of a dam classified as having a severe, moderate or low cold water pollution status, according to Preece (2004).

The objective for recreational water quality is to achieve a low risk to human health from water quality threats posed by exposure through ingestion, inhalation or contact during recreational use. Blue-green algae were chosen as the indicator for risk to recreational water quality because of the potential for some species to impact on human health. The risk of water being unsuitable for recreational use considered the frequency of high concentrations of potentially toxic algal blooms (likelihood), compared to the degree of recreational usage of the water body where the sample was taken (consequence).

New South Wales currently manages the risk of human exposure to blue-green algal blooms through a coordinated regional approach with the Regional Algal Coordination Committees (RACC). State-wide and regional contingency plans and guidelines have been developed to provide methodologies on the



management of algal blooms (NSW Office of Water 2014). The objective of the guidelines is to provide a risk assessment framework to assist with the effective management response to freshwater, estuarine and marine algal blooms. They aim to minimise the impact of algal blooms, by providing adequate warning to the public ensuring their health and safety in recreational situations and for stock and domestic use.

Under the current management of algal blooms, the level of human exposure to a bloom can be reduced by management practices such as issuing algal alerts. Alert levels have been developed and are used to determine the actions that need to be undertaken with respect to an algal incident. These alerts have been adopted from the National Health and Medical Research Council algal bloom response guidelines (NHMRC 2008). The risk to a site with a high recreational usage may be reduced by the management strategy of placing algal warning signs at the site and informing users of the risks and dangers. Therefore the initial risk assessment outcomes were reviewed and an adjustment in the consequence values made to reflect the application of these arrangements.

Pathogens, pesticides, heavy metals and other toxic contaminants are not monitored regularly in the Murray Lower Darling WRPA, so were not included in the risk assessment.

6. Results

6.1. Water quality index (WaQI)

6.1.1.Water-dependent ecosystems

The Water Quality Index (WaQI) score for each parameter, and the overall score for each site, was calculated for the 2010 to 2015 water quality data set. There were five sites rated as poor: the Tooma River at Warbrook, Wakool River at Stoney Crossing and Kyalite and the Darling River at Weir 32 and Burtundy. The Edward River at Deniliquin, Murray River at Barham and Euston Weir were rated as fair with all other sites, good. The results from the WaQI are shown in Table 12 and summarised in Figure 6.

Table 12: Water quality index scores for the Murray and Lower Darling WRPA 2010-2015 water quality data

Station Name Rating WaQI Total N Total P Turbidity pH DO

Murray River at Indi Bridge Good 88 93 86 67 100 100

Tooma River at Warbrook Poor 54 55 35 21 96 80

Murray River at Jingellic Good 80 89 74 46 100 96

Murray River at Albury (Union Bridge) Good 85 91 90 93 87 66

Murray River downstream Yarrawonga Weir Good 81 85 82 76 76 85

Edward River at Deniliquin Fair 63 85 43 25 89 79

Wakool River at Stoney Crossing Poor 53 50 27 50 93 49

Wakool River at Kyalite Poor 47 55 27 19 94 51

Murray River at Barham Fair 61 72 51 23 92 82

Murray River upstream Euston Weir Fair 77 77 79 67 89 72

Murray River at Merbein Pump Station Good 80 81 82 68 90 78

Darling River at Menindee Weir 32 Poor 26 17 7 18 65 56

Darling River at Burtundy Poor 30 18 9 24 71 65

Murray River at Lock 8* Good 92 100 90 84 100 85

* NOTE: There is only two years of water quality data for the Murray River at Lock 8. Monitoring commenced at this site in July 2013.



Figure 6: Murray Lower Darling WRPA water quality index scores



6.1.2.Water temperature

In the Murray River catchment upstream of Hume Dam there is a continuous water temperature data set for two sites. The Murray River at Biggera is approximately 150 km upstream of Hume Dam, and Murray River at Jingellic is 40 km above full supply level. The monthly 20th and 80th percentiles were calculated using the Murray River at Jingellic hourly water temperature data. The Biggera site was not included due to the distance upstream and the difference in altitude. The monthly median temperature downstream of Hume Dam was calculated using the hourly water temperature data from the Murray River at Heywoods gauging station. Figure 7 compares the monthly median temperature at the downstream Hume Dam site to the percentiles of the reference site. The thermal pollution WaQI score, using the difference between the reference site and downstream data was 42, which is a poor rating.

The water temperature data in Figure 8 is the daily minimum water temperature at the site upstream and three sites downstream of Hume Dam. The Murray River at Heywoods (409016) is approximately 1.2 km below the outlet. Further downstream it is 26 km to Albury (409001) and 134 km to Corowa (409002). The Murray River reaches the impoundment of Lake Mulwala approximately 200 km from Hume Dam.

Jul-2009 Nov-2010 Apr-2012 Aug-2013 Dec-2014 May-2016

0

5

10

15

20

25

30

Wate

r T

em

pera

ture

(°C

)

Reference 20%ile

Reference 80%ile

Downstream Hume median

Figure 7: Water temperature downstream of Hume Dam compared to estimated 20th and 80th percentile of natural temperature




0

5

10

15

20

25

30

Min

imum

daily w

ate

r te

mpera

ture

(°C

)

Murray at Jingellic

Murray at Heywoods

Murray at Albury

Murray at Corowa

Figure 8: Minimum daily water temperature in the Murray River upstream and downstream of Hume Dam

6.1.3.Dissolved oxygen

There are numerous continuous dissolved oxygen sensors installed in the Murray Lower Darling WRPA as an early warning for possible hypoxic events and to assist in the delivery of environmental water during an event. Figure 9 illustrates that dissolved oxygen in the Darling River was generally suitable to maintain ecological process and support aquatic life. The red line shows the Basin Plan dissolved oxygen target for managing water flows (50% saturation). In 2012 and 2016, major flooding resulted in hypoxic blackwater events in the mid Murray River catchment, with dissolved oxygen concentrations dropping to critical levels in the Edward, Wakool and Niemure Rivers (Figure 10).



Apr-2012 Oct-2012 May-2013 Nov-2013 Jun-2014 Dec-2014 Jul-2015 Jan-2016 Aug-2016 Mar-2017

0

50

100

150

200

250

Dis

solv

ed o

xygen (

% s

atu

ration)

Figure 9: Dissolved oxygen in the Darling River at Burtundy from 2012 to 2017

Apr-2012

Oct-2012

May-2013

Nov-2013

Jun-2014

Dec-2014

Jul-2015

Jan-2016

Aug-2016

Mar-2017

Sep-2017

0

25

50

75

100

125

150

Dis

solv

ed o

xygen (

% s

atu

ration)

Muray River at Barham

Edward River at Moulamein

Wakool River at Stoney Crossing

Niemure River at Barham-Moulamein Road

Figure 10: Dissolved oxygen in the mid Murray River and Edward-Wakool system from 2012 to 2017

6.1.4.Irrigation

The agriculture and irrigation salinity target is for the 95th percentile of the daily mean electrical conductivity, over a 10 year period, not to exceed 833 µS/cm. This target applies at sites where water is extracted by an irrigation infrastructure operator for the purpose of irrigation. The 95th percentile of the 2005 to 2015 electrical conductivity data set and results of the WaQI are shown in Table 13.



Table 13: Water quality index scores for the Murray Lower Darling WRPA 2005-2015 continuous electrical conductivity data

Station Number Station Name 95th

percentile WaQI Rating

409002 Murray River at Corowa 76 100 Excellent

409025 Murray River downstream Yarrawonga Weir 69 100 Excellent

409215 Murray River at Barmah 70 100 Excellent

409005 Murray River at Barham 132 100 Excellent

409023 Edward River downstream Stevens Weir 111 100 Excellent

409202 Murray River at Tocumwal 65 100 Excellent

409204 Murray River at Swan Hill 212 100 Excellent

414216 Murray River downstream Mildura Weir 218 100 Excellent

414217 Murray River at Curlwaa 224 100 Excellent

425017 Darling River at Wentworth 471 100 Excellent

A4260501 Murray River upstream Lock 9 305 100 Excellent

The mean daily electrical conductivity in the Edward and Murray Rivers fluctuates throughout the year, though results do not exceed the agriculture and irrigation salinity target (Figure 11). As the target is not exceeded, the risk of any impacts to soil and crop health is minimal. The Wakool River at Stoney Crossing had very high electrical conductivity results between 2007 and 2010, reaching a peak of 6 339 µS/cm in November 2008. Comparing electrical conductivity and mean daily flow (Figure 12) illustrates the impact of increased flows after 2010, diluting salts in the Wakool River.

May-2005 Oct-2006 Feb-2008 Jul-2009 Nov-2010 Apr-2012 Aug-2013 Dec-2014

0

100

200

300

400

500

600

Mean d

aily e

lectr

ical conductivity (

µS

/cm

)

Murray River at Corowa

Murray River at Swan Hill

Edward River at Leiwah

Murray River US Lock 9

Figure 11: Mean daily electrical conductivity (µS/cm) at selected sites in the Murray valley from 2005 to 2015



Apr-2008 Mar-2009 Mar-2010 Feb-2011 Feb-2012 Jan-2013 Jan-2014 Dec-2014

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10000

15000

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35000

Mean d

aily flo

w (

ML/d

ay)

Electrical conductivity (L)

Mean daily flow (R)

Figure 12: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Wakool River at Stoney Crossing from 2007 to 2015

High electrical conductivity results were recorded in the Darling River at Burtundy during low and cease to flow periods when salts become further concentrated by evaporation (Figure 13). Electrical conductivity results exceed the Basin Plan agriculture and irrigation salinity target (833 µS/cm) and the target for managing water flows in the Darling River (830 µS/cm). The spike in electrical conductivity of over 3 400 µS/cm in August 2016 coincided with the recommencement of flows following an extended period of no flow. Electrical conductivity in the Murray River at Lock 6 did not exceed the flow management target of 580 µS/cm (Figure 14).



Oct-2006 Feb-2008 Jul-2009 Nov-2010 Apr-2012 Aug-2013 Dec-2014 May-2016

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4000

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aily e

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ical conductivity (

µS

/cm

)

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5000

10000

15000

20000

25000

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aily flo

w (

ML/d

ay)


Flow (R)

Figure 13: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Darling River at Burtundy from 2005 to 2017 (red line indicates 833 µS/cm irrigation salinity target)


0

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µS

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aily flo

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ay)


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Figure 14: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Murray River at Lock 6 from 2008 to 2017 (red line indicates 580 µS/cm flow target)

6.1.5.Recreation

Blue-green algae biovolume data are used to assign recreational alerts based on the National Health and Medical Research Council guidelines. At the red alert level (4 mm3/L), waters are not suitable for recreational



use, and exceed the Basin Plan target. There were major algal blooms in the Murray River in 2009, 2010 and 2016. However, as there were no major algal blooms in the Murray River between 2010 and 2015, the result was excellent WaQI scores for all sites.

In March 2009, high concentrations of cyanobacteria were detected by routine monitoring in Lake Hume. Following the detection of the bloom, additional downstream monitoring indicated that cyanobacteria was present in the Murray River for a distance of 1 000 km, including associated tributaries of Gulpa Creek, Edward River and Wakool River. The potentially toxic taxa Anabaena circinalis (Dolichospermum circinale), Cylindrospermopsis raciborskii and Microcystis flos-aquae were detected at the majority of the sampling sites during March and April 2009. The algal biovolumes in the Murray River in late March, ranged from 5 to 9 mm3/L. Biovolumes had decreased to below 4 mm3/L by late April/early May 2009.

An unusual bloom of Chrysosporum ovalisporum occurred in the Murray River from mid-February to early June 2016. At its greatest extent in April and May, it extended from Lake Hume to Lock 8 and throughout the Edward, Wakool and Niemur River distributary system, a combined river length of about 2 360 km. It also extended into distributary systems in Victoria. Bloom densities at times exceeded 40 mm3/L, and C. ovalisporum usually comprised >99% of the total bloom biovolume at most locations sampled.

The potentially toxic blue-green algae biovolume data from selected locations, displayed in Figure 15 for the Upper Murray and Figure 16 for the Edward-Wakool system, extends from January to July 2016, and highlights the extent and severity of the bloom. The red line is the National Health and Medical Research Council (2008) recreational use guideline.

Murray River at Albury

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Figure 15: Potentially toxic algal biovolume (mm3/L) at selected sites in the Murray River from January to July 2016



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Figure 16: Harmful algal blooms at selected sites in the Edward Wakool River system from January to July 2016

6.2. Literature review A literature search was undertaken to gather information from the published literature relevant to water quality in the Murray Lower Darling WRPA. Following is a summary of relevant information with more detailed information listed in Appendix C.

Habitat condition is degraded across much of the Murray Darling Basin. Loss of riparian vegetation and increased sand and gravel bed load are the principal components causing degradation. The most marked degradation is in the mid slopes (Norris et al. 2001). Riparian vegetation is important as a carbon source, its shading reduces solar radiation, limiting in-channel autotrophic production (Kelleway et al. 2010) and as a source of large woody debris to protect against erosion and restore river health (Erskine et al. 2012). The most impacted areas are in the Edward - Wakool system, Lower Murray River and Darling River near Menindee Lakes, with some long reaches of less than 20% native woody riparian vegetation. Inversely, in the upper Murray catchment there are long reaches with greater than 80% cover (DoIW 2018b).

Parts of the Murray River are extremely impaired, with 43% of the Murray-Riverina area and 19% of the Darling River substantially modified. Parts of the Murray River may have lost over 80% of the biota likely to have occurred there (Norris et al. 2001). Water temperature, flows, habitat and food resource (prey size and availability) all impair fish recruitment. Flow magnitude and water temperature appear to have the largest effect in determining larval fish composition (Rolls et al. 2013). It is suggested that a lack of prey and food resources may be one reason why there is not a strong response to managed flow events (Rolls et al. 2013). In the Great Darling Anabranch, the fish community is dominated by carp as there is little habitat available for native fish, except during floods (Thoms et al. 2000). Water quality has also been found to have an effect on river red gum survival (Kingsford 2000).

Where river channels have already been impacted by regulated flows, complex surfaces such as benches may have already been lost, so restoring more natural flows at these levels of channel, may have little immediate impact on nutrient processing (Woodward et al. 2015). Low level benches will need to be ‘rebuilt’ before environmental flows can increase connectivity.

Discharge temperatures from Hume Dam during spring and summer may be depressed by more than 5°C relative to the temperature in the surface layer of the reservoir (Sherman 2005). Two options proposed by



Sherman (2005) for mitigation of cold water pollution include: construction of a multi-level offtake, or deployment of a submerged curtain. The submerged curtain option was expected to produce the greatest discharge temperature. Increased discharge temperatures appear to be achievable and are expected to reduce the stress currently impacting Murray cod populations during crucial post-spawning periods (Sherman et al. 2007).

Developing ecologically effective environmental flow regimes is a challenge for river managers globally, and in many regulated rivers, sufficient water is rarely available to ensure that environmental flow releases are fully effective (Dyer and Thoms 2006). Estimates are that climate change my reduce water yield in the Upper Murray River (18% by 2030 and 43% by 2070), the Murray-Riverina (21% by 2030 and 48% by 2070) and Darling River (26% by 2030 and 57% by 2070) (Austin et al. 2010).

Nutrient and sediment loads from the Australian Alps are largely unmodified. Most of the loads are generated in the upland and mid-slope areas, while most of the impact is felt in lowland rivers, weir pools and reservoirs where the sediment is stored (Norris et al. 2001). In the long-term, management needs to focus on reducing sediment supply, but the greatest short-term benefits will come from managing the lowland sediment and nutrient stores.

Flow releases from Menindee Lakes were assessed for their ability to either suppress bloom development, or to mitigate pre-existing blooms in the Darling River. A discharge of 300 ML/day (flow velocity of 0.03 m/s) was found to be sufficient to prevent prolonged periods of persistent thermal stratification, which also suppressed the development of Anabaena circinalis blooms (Mitrovic et al. 2011). Mitrovic et al. (2011) also found a flow release of 3 000 ML/day was effective at removing an established cyanobacterial bloom, with total cyanobacterial numbers declining from over 100 000 to 1 000 cells/mL within a week. In two summers without blooms, higher flows and decreased light availability prevented bloom development. As well as flushing algae downstream, greater discharges increased turbidity, which diminished the growth of cyanobacteria through reduced light availability (Mitrovic et al. 2011).

6.3. Lower Darling flow release and water quality event The cessation of water releases from Menindee Lakes to the lower Darling in December 2015 was a contingency measure to protect water supply to Broken Hill during an unprecedented low inflow period. The result was remnant pools in the lower Darling River would decline in both water quality and quantity, with water retreating to standing pools during 2016. The water quality in the remnant pools used for water supply was surveyed in April 2016 and was found to be generally poor with high electrical conductivity readings up to 3 500 µS/cm and high algae concentrations.

There are numerous risks involved when returning flows to a river that has stopped flowing, sometimes referred to as ‘re-starting’ a river:

As poor quality water is flushed downstream, it may be unusable for some water user enterprises;

Water with low or zero dissolved oxygen often sits on the bottom of stagnant pools. The flushing of this water can cause fish kills in pools downstream;

Some elements are released at harmful concentrations from river sediments under zero oxygen conditions. These could have toxic effects on plants and soil if used for irrigation;

Denser saline water can flow along or sit on the bottom of pools, leaving the fresher water sitting on top, and

The water in stagnant pools can have high nutrient concentrations, triggering potentially toxic blue-green algal blooms downstream.

Rainfall in May/June 2016 brought inflows to Menindee Lakes, allowing releases to the lower Darling River to resume. The aim was to release a large volume 'flush' from Lake Wetherell to eject poor quality water from the standing pools, and flush it into the Murray River. The initial intention was to flush the poor quality water past Burtundy, to provide some relief for water users on the Darling River. This would result in poor quality water passing the water users around Ellerslie and Tapio and mixing with the better quality water in this stretch of river that is supplied by the weir pool behind Lock 10.



The initial flush volume suggested as necessary was far greater than could be contemplated at that time. The forecast inflows to Menindee Lakes were limited, and would be set aside mostly to extend the water supply security for Broken Hill and to provide longevity of low flow in the lower Darling River. At the time, the Menindee system was still well below 10% storage capacity. A budget of 35 000 ML was made available for release, with a commencement date of 28 July 2016.

In 2004, the lower Darling River received the return of flows after a period of drought. The release started at a flow rate of 40 ML/day and increased to 200 ML/day over a period of weeks. The Darling River at the time was a series of pools, and being summer, these pools were thermally stratified, resulting in the water in the bottom of pools having low dissolved oxygen. The flushing of this deoxygenated water from the pools resulted in fish-kills downstream. The 2016 release was undertaken at the end of winter, when the pools were not stratified, and a larger volume was released to dilute the poorer quality water, ensuring the water was mixed through the profile, reducing the risk to aquatic ecosystems.

There was an additional confounding factor influencing the timing of the 2016 release. There were concerns about the poor quality of the water to be released from Lake Wetherell. The inflows to Lake Wetherell at the time were carrying high salinity loads from the upper Darling River. Monitoring near the main weir showed the electrical conductivity in May 2016 had increased to over 2 000 µS/cm (Figure 17). The inflows were held in Lake Wetherell for a short period, to enable some dilution and mixing of the inflows with water within the storage. Water quality profile data was collected from Lake Wetherell by WaterNSW to determine when the release should commence. At the start of the release on 28 July, inflows of lower salinity water had diluted the electrical conductivity in Lake Wetherell to 1 200 µS/cm. By 5 September, the electrical conductivity was 337 µS/cm.

To further mitigate risk during the release:

The quality of the flows were monitored prior to and as they progressed down the Darling River. The main aim of the sampling program was to collect water samples from the head of the flow as it progressed down the Darling River to enable notification of water users of the quality of the water. In addition, information on the quality of the water in the tail of the flow was also needed, to enable water users to determine when the water was safe for use in their enterprise;

Water users were notified of the quality of the water throughout the release so they could make informed decisions about their enterprises;

Releasing water into the lower Darling and flushing remnant pools in winter, at a time of lower risk, may alleviate water use and environmental issues in the coming summer;

The release was being managed by multiple agencies including, DoI Water, WaterNSW and DPI Fisheries to maximise beneficial outcomes and minimise risks, and

It was acknowledged that there may be a need for contingency sampling in the event of reported fish kills at sites as advised by NSW DPI Fisheries Officers. These were to be coordinated between the various agencies if/when the situation arose.

The electrical conductivity in Weir 32 was approximately 2 000 µS/cm prior to the release. The arrival of the release saw the conductivity drop rapidly to 1 000 µS/cm and then continue to decrease with time. The progression of the head of the flow down the Darling River flushed the saline water from the standing pools, resulting in the electrical conductivity increasing to over 3 600 µS/cm at Pooncarie and 3 500 µS/cm at Burtundy. The electrical conductivity declined rapidly as the first flush passed each of the gauging stations (Weir 32, Pooncarie and Burtundy) (Figure 18). The flow data from the Darling River at Burtundy shows that once the river was flowing, subsequent flows did not result in increased electrical conductivity.



Feb-2008 Jul-2009 Nov-2010 Apr-2012 Aug-2013 Dec-2014 May-2016

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Figure 18: Continuous electrical conductivity (µS/cm) at Darling River gauging stations

The quality of the water in the Wentworth weir pool became an issue once the head of the flow entered the upper reaches near Ellerslie. The electrical conductivity at Ellerslie increased from 153 µS/cm on 5 July, to 2 755 µS/cm on 22 August. Similarly, the pH increased from 7.09 to 8.52 and the sodium adsorption ratio from 1.53 to 9.00. A sodium adsorption ratio of greater than 6 has increased effect on all soils and starts to reduce growth of most crops and pasture plants (NSW DPI 2014). The change in the quality of the water in the Wentworth weir pool directly impacted water users in the area.



Due to the volume of water flowing down the Murray River at the time (32 000 ML/day), there were concerns that the saline water would sit on the bottom of deeper holes in the Wentworth weir pool and not be flushed out of the Darling River, impacting on irrigation enterprises. In response to this, a second release was proposed. An additional profile monitoring program was commenced on 31 August by WaterNSW, to track the movement of the poor quality water through the Wentworth weir pool. The electrical conductivity results in the following tables have been highlighted to indicate the progression of the denser saline water Through the weir pool. Results less than 1 000 µS/cm are green, between 1 000 and 2 900 µS/cm are amber and greater than 2 900 µS/cm are red. Tables 14 to 19 track the movement in the saline water down the Darling and into the Murray River. Distances are measured upstream from the junction of the Darling and Murray Rivers. Samples from the Murray River were collected on the NSW/Lock chamber side of the river.

It took 25 days for the head of the saline first flush from the initial release to travel from Lake Wetherell to the upper reaches of the Wentworth Weir pool near Ellerslie. The highly saline first flush then moved slowly through the weir pool, taking 24 days to commence merging into the Murray River. The salt plume, being denser than fresh water, made its way along the bed of the weir pool. It was a further 28 days before the saline water had been fully dispersed from the Darling River into the Murray River.

Table 14: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 31 August

Depth (m) 19 km 22 km 39 km

0.5 143 160 3041

1.0 143 160 3026

2.0 144 164 3001

3.0 141 786 3028

4.0 135 896 3187

5.0 132 918 3283

Table 15: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 7 September

Depth (m) 4 km 8 km 14 km 18 km 20 km 24 km 30 km 38 km 42 km 46 km 52 km

0.5 116 131 173 202 289 517 1900 1976 1858 1847

1.0 117 132 167 175 202 309 839 1903 1978 1858 1847

2.0 121 131 160 176 316 1329 1984 2120 2007 1901 1847

3.0 127 132 304 780 1721 2584 2527 2400 2291 1870

4.0 128 582 2099 1940 2667 2938 2980 2840 3192 3117 2138

5.0 129 680 2236 2497 2967 2983


Depth (m) Murray

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Junction

1 km 3 km 9 km 14 km 20 km 28 km 32 km 36 km 44 km

0.5 116 132 121 277 317 676 1472 1909 1961 1765

1.0 116 132 121 152 273 419 703 2005 1992 1958 1772

2.0 117 133 133 163 368 804 968 2568 2046 2003 1788

3.0 117 133 321 448 1803 2333 2534 2819 2409 2266 2552

4.0 118 133 594 1128 2216 2526 2654 2691 2391 3105

5.0 119 132 622 1350 2234 2679


Depth (m) Murray

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U/S

Junction

3 km 8 km 12 km 16 km 20 km 26 km 30 km 34 km 40 km

0.5 415 907 1690 2122 2006 1805 1468 1150 1078 1019 988

1.0 366 961 1714 2122 2006 1808 1465 1149 1080 1019 988

2.0 379 972 1715 2123 2007 1808 1476 1149 1080 1020 988

3.0 423 1262 1718 2127 2007 1811 1486 1150 1080 1021 988

4.0 457 1437 1722 2193 2007 1815 1491 1151 1080 1021 988

5.0 462 1654 1981 2008 1820 1499 1080 1021




Depth (m) Murray

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boat ramp

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0.5 288 713 252 1111 1012 954 878 865 853

1.0 339 742 302 1115 1013 954 878 866 855

2.0 355 782 1006 1122 1014 955 879 864 855

3.0 373 803 1182 1130 1044 953 883 864 855

4.0 388 914 1295 1123 1082 956 886 864 892

5.0 395 1023 1417 1608 943 865

Table 19: Electrical conductivity profiles from Lock 10 and Darling River at Wentworth – 13 October

Depth (m) Wentworth

boat ramp

10 km 20 km 30 km 40 km 50 km 60 km

0.5 384 464 516 475 449 405 367

1.0 394 464 516 475 449 405 367

2.0 443 464 516 475 450 405 367

3.0 581 464 516 475 450 405 367

4.0 638 465 516 475 450 405 367

5.0 640 465 516 475 449

Monitoring of additional sites within the Lock 10 weir pool showed that when the saline water from the Darling River was able to push into the Murray River, it largely stuck to the lock chamber side of the weir (NSW bank). The results of profiles collected approximately 1.2 km downstream of Lock 10 showed that the electrical conductivity was slightly higher mid river and on the NSW side than closer to the Victorian bank, but generally the results indicate the waters were well mixed and would not impact downstream water users.

Recommendations for future releases include:

Salinity and hydrology:

Hydraulic modelling of the Murray and Darling River to better understand the movement of the salt slug captured in the Lock 10 Weir pool.

Risk management and stakeholder communication:

Prior survey and event monitoring of the Darling River, Lake Wetherell and Wentworth Weir pool;

Functional arrangements and roles of WaterNSW and DoI Water; operational and customer service, and

Discussion of utilisation of block banks and manipulation of Lock 10. Governance of the Water Management Act and subordinate Policies:

Governance of water release decisions;

Regulatory instruments (works approval), and

Implementation of Lower Darling Water Sharing Plan rules. Basin Plan Implementation – Water Quality Management Plans (and WRPs):

First flush flows and ecological objectives;

Water quality targets when managing flows, and

Water quality objectives and measures.

6.4. Summary statistics Boxplots have been used to show general water quality trends across the valley, and to display monitoring site variability within the Murray and Lower Darling WRPA. The boxplots in Figure 16 show the annual 25th, 50th

and 75th percentile values, with error bars indicating the 10th and 90th percentile values for each water quality attribute at each site. There are numerous plots within Figure 19; A) total nitrogen, B) total phosphorus, C) turbidity, D) total suspended solids, E) dissolved oxygen, F) pH and G) electrical conductivity. Summary statistics for the key water quality parameters at each monitoring site have been displayed as tables in Appendix D. Additional detail for each individual site is shown in Appendix E.



The two sites located on the Darling River at Weir 32 and Burtundy had the highest nutrient concentrations and highest turbidity, followed by the Wakool River at Stoney Crossing and Kyalite. In the regulated Murray River there was a slight increase in nutrient concentration and turbidity between Albury and Lock 8, reflecting the impact of the cumulative effects of land use, soil disturbance and human activity on water quality. The concentrations of nutrients detected are not limiting to algal growth.

Dissolved oxygen levels fluctuate between sites in response to local drivers. In most cases, the site median was between 80 and 100% saturation. The highest readings were in the Murray River at Lock 8 and the lowest dissolved oxygen readings were in the Darling River at Weir 32 and Burtundy. The pH in the Darling River was slightly elevated (basic), but not to the extent where it would impact on the health of aquatic ecosystems or agricultural enterprises.

The electrical conductivity in the Murray River was generally low. The release of water from Hume Dam provides dilution flows to the Murray River, and the operation of salt interception schemes help manage salt inputs from saline groundwater. The Wakool River at Stoney Crossing had very high electrical conductivity results during periods of low or zero flow between 2007 and 2010. Electrical conductivity did not increase markedly with distance down the Murray River to Barham, but there was a slight increase between Barham and Lock 8. The annual median electrical conductivity and salt loads are summarised in Tables 28 to 30 in Appendix D.

Draftsman plots for each site have been developed to assess the relationships between water quality parameters. These figures are shown in Appendix E. Sites generally showed a positive correlation between total nitrogen, total phosphorus and turbidity, indicating similar transport mechanisms for the three parameters. This suggests that nutrients are mostly transported in the river system bound to particulate matter. The highest total nitrogen and total phosphorus concentrations tend to coincide with increased flow. This indicates that the majority of the nutrients are derived from diffuse sources rather than point sources. In addition, there are occasional high readings during low flow, indicating a mixture of nutrient sources, such as livestock access or release of nutrients from bed sediments at some sites. In contrast to nutrients and turbidity, electrical conductivity was negatively correlated to flow and decreased as salts are diluted by increased flow.



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Figure 19: Water quality data for water quality parameters by site



6.4.1.Total annual flow

Many water quality attributes are strongly correlated to river flow conditions. Flow during the 2010 to 2015 data period was characterised by high flows in 2010 and 2011, and low flow from 2013 to 2015. The storage capacity of Hume Dam was less than 20% in April 2010. Following heavy rainfall between August and October, Hume Dam filled to 100% capacity. There were no major inflows from 2013 to 2015. Figure 20 illustrates the total annual flow at selected gauging stations from the upland, midland and lowland areas. The use of total annual flow gives a general indication of river flow conditions. No attempt has been made to assess individual results against flow at the time of sampling, or the timing of sampling in relation to high or low flow events. The general trend at most sites were higher nutrient and turbidity results during the wetter years and lower concentrations during the dryer years.

2010-2011 2011-2012 2012-2013 2013-2014 2014-2015

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Darling at Pooncarie

Figure 20: Annual flow (ML/year) at selected gauging stations

6.5. Risk assessment The impact of the quality of the water in the Murray and Darling Rivers on the health of water dependent ecosystems was assessed by identifying the risk. This was achieved by quantifying the impact based on instream values (consequence) and determining the probability of that consequence occurring (likelihood). Tables 20 to 24 list the sites with medium or high risk scores in the Murray Lower Darling risk assessment for each parameter. The Murray River at Barham had a high risk for turbidity, total phosphorus and total nitrogen. The Tooma River at Warbrook, Edward River at Deniliquin, Wakool River at Kyalite, Darling River at Burtundy and Murray River at Lock 8 were also a high risk for turbidity.



Table 20: Sites with high and medium risk to the health of water dependent ecosystems from turbidity

Station Name Consequence Likelihood Level of Risk

Tooma River at Warbrook Medium High High

Murray River at Jingellic Medium Medium Medium

Edward River at Deniliquin High High High

Wakool River at Kyalite High High High

Murray River at Barham Very high High High

Murray River upstream Euston Weir High Medium Medium

Darling River at Menindee Weir 32 Low High Medium

Darling River at Burtundy Medium High High

Murray River at Lock 8 Medium High High

Table 21: Sites with high and medium risk to the health of water dependent ecosystems from total phosphorus


Tooma River at Warbrook Medium Medium Medium

Edward River at Deniliquin High Medium Medium

Wakool River at Kyalite High Medium Medium

Murray River at Barham Very high Medium High

Murray River upstream Euston Weir High Medium Medium

Darling River at Burtundy Medium Medium Medium

Murray River at Lock 8 Medium Medium Medium

Table 22: Sites with high and medium risk to the health of water dependent ecosystems from total nitrogen


Tooma River at Warbrook Medium Medium Medium


Murray River at Barham Very high Medium High

Daring River at Burtundy Medium Medium Medium

Murray River at Lock 8 Medium Medium Medium

Table 23: Sites with high and medium risk to the health of water dependent ecosystems from pH


Murray River at Barham Very high Low Medium


Table 24: Sites with high and medium risk to the health of water dependent ecosystems from dissolved oxygen


Murray River at Union Bridge (Albury) Medium Medium Medium


Murray River at Barham Very high Low Medium




There was a medium risk to water dependent ecosystems from salinity in the Murray River at Barham and Lock 8. The highest value at Lock 8 across the five year period was 572 µS/cm. The risk to all irrigation infrastructure operators throughout the WRP area from salinity, was low.

There was a high risk to water dependent ecosystems from thermal pollution from Hume Dam and a medium risk to water dependent ecosystem from Khancoban Dam. Most inflow to Khancoban Dam is transferred from Island Bend Pondage, Lake Eucumbene and Lake Jindabyne.

Numerous sites were routinely monitored for blue-green algae between 2010 and 2015. When algal blooms occur, the level of human exposure can be reduced by implementing management practices such as issuing algal alerts. The risk at a site with a high recreational usage can be reduced by the management strategies of erecting algal warning signs and informing users of the risks and dangers. The risk assessment consequence values reflect the implementation of these arrangements. The risk outcome for Lake Hume, Lake Wetherell and Lake Pamamaroo was medium.

7. Discussion Water quality attributes in the Murray Lower Darling WRPA are strongly correlated to flow. High flow from rainfall and runoff can result in higher turbidity, nutrients and possibly pesticides and pathogens, but lower electrical conductivity. The Basin Plan water quality targets were developed using data collected from 1991 through to 2009, to try and incorporate a spread of climatic and flow conditions (Tiller and Newall 2010). It was noted that although the time period covered a range of conditions, the data used was primarily collected at base or low flow, and generally missed high flow and flood events. It should be noted that as the Basin Plan targets refer to low flow conditions, targets for flow dependent attributes are likely to be exceeded in wetter years. There was a general trend of higher nutrient and turbidity results in the wetter years from 2010 to 2012, with many very high results collected in these years and annual medians exceeding the Basin Plan targets.

Where there was inadequate reference site data or locally derived guidelines for a zone during the development of the Basin Plan, the target was based on the ANZECC Guidelines (2000) for slightly modified waterways (Tiller and Newall 2010). This has had significant implications for the reporting of water quality condition in the Darling River; with the illogical scenario of more stringent targets in lower reaches compared to upstream catchments. For example, the turbidity target decreases from 230 NTU in the Darling upper zone to 50 NTU in the middle lower zone. The targets should account for the trend of increasing sediment loads and nutrient concentrations with distance down the catchment. Tiller and Newall (2010) identified the middle and lower zones of the Darling River as a ‘hot spot’ in terms of turbidity and nutrients and suggested the proposed targets may be too low and need refinement.

In the Basin Plan, the middle and lower reaches of the Darling River are combined into one zone. It could be expected that the water retention time in Menindee Lakes would allow the settling of particulate matter, resulting in reduced turbidity, total phosphorus and total nitrogen in the river downstream of the lakes. An assessment by Mawhinney and Muschal (2015) found this does not appear to be the case. The large shallow lakes that make up the Menindee Lakes system are exposed to the wind and are well mixed. The re-suspension of fine sediments from the bottom maintains high turbidity in the lakes. This turbid water is then released downstream. For this reason it appears appropriate to use the same targets in the middle and lower zones of the Darling River.

Water quality application zone boundaries were reviewed by Mawhinney and Muschal (2015) and one major change in the Murray WRPA was recommended. In the Central Murray zone (cMum), the smaller regulated Edward - Wakool Rivers function as lowland rivers, especially when compared to the Murray River at Albury and downstream of Yarrawonga Weir. A change to the central Murray River zone boundary was suggested so that the Edward - Wakool Rivers (and Billabong Creek in the Murrumbidgee WRPA) are separated from the Murray River, which could retain the existing central Murray targets.

7.1. Elevated levels of salinity Assessment of the discrete electrical conductivity data has shown the highest salinity results are in the Darling River and the Wakool River during zero and low flow periods. Electrical conductivity levels are low in the



Murray River with regulated flows from Hume Dam diluting salt, keeping electrical conductivity low. The 95th

percentile of the daily mean electrical conductivity did not exceeded the 833 µS/cm target for irrigation at any of the irrigation infrastructure operator offtakes on the Murray and Lower Darling Rivers. The highest was at the bottom of the system downstream of Mildura Weir and at Lock 9 with a 95th percentile of 218 and 305 µS/cm respectively. At these sites, the risk of crop damage and increased soil salinity is low.

Brock et al. (2005) showed that aquatic plant germination and species richness in wetlands decreases when salinities increase above 300 mg/L (500 µS/cm). The electrical conductivity in the Murray River is rarely above this level, and unlikely to impact on species diversity. It was found that increased salinity (up to 5 000 mg/L) had no effects on the Darling Anabranch, with no change in community structure.

The median data from the unregulated catchments shows a gradual increase in electrical conductivity following the commencement of heavy rainfall across the catchment in 2010. McGeoch et al. (2017) hypothesised that an episodic decline in salinity in NSW rivers during the 2000’s may have been due to extended drought conditions. Long periods of low rainfall can cause a drop in shallow groundwater levels, resulting in a disconnection between saline groundwater and fresher surface water, causing the observed lower salinity levels in streams. The return of wetter conditions in 2010 would have recharged shallow water tables, increasing the contribution of groundwater to low flows, raising the electrical conductivity. In all cases the median electrical conductivity had started to decline in 2014/2015 following the return of dryer conditions. Future monitoring will show whether recent salinity observations in unregulated catchments persist at current levels or decrease as shallow saline groundwater aquifers decline.

Electrical conductivity increases very slightly with distance down the Murray River. Parsons et al. (2008) found the Murray River varies between being a losing stream and a gaining stream as it progresses down the catchment. The electrical conductivity of surface water in the lowlands area is generally considered excellent for irrigation purposes, but can be high in the lower Wakool River during low flow periods. The mean daily electrical conductivity in the Murray River fluctuates throughout the year, though results do not exceed the agriculture and irrigation salinity target, keeping the risk of impacts on soil and crop health low.

Maintaining low flow in unregulated catchments and ensuring that freshes are available to the environment, helps to break up stratification, provide dilution flows and prevent saline water from sitting on the bottom of pools. This will maintain the health of the river and the continued use of the water for productive purposes. Water released from Hume Dam has a low electrical conductivity and dilutes saline inflows from unregulated tributaries, ensuring water is suitable for irrigation and the protection of water dependent ecosystems. Generally the river systems in the upper catchment remain relatively fresh. However salinity in the lower Murray (the Mallee region), in particular below the South Australian border, can approach critical levels. The operation of numerous salt interception schemes in the Lower Murray by both NSW and Victorian agencies reduce salt inputs to the Murray River from saline groundwater. There is a delicate balance in the interface between the groundwater regime and the river regime.

Salinity mitigation is currently achieved through the diversion of irrigation drainage waters or groundwater interception. Investigations have identified historical poor irrigation practices combined with poor location of irrigation developments as a major contributor of additional salt to the Murray River. Improved irrigation practices offer opportunities for both irrigators and natural resource managers. Significant effort has been made to foster improved irrigation practices through research and practical on-farm education. Irrigators have been able to reduce water consumption, resulting in reduced recharge (root zone drainage) to the groundwater system. Groundwater modelling suggests that the irrigation induced salt accessions throughout the Mallee region could reduce substantially, putting off the need for further salinity mitigation investments (Newman 2010).

The cessation of water releases from Menindee Lakes into the Lower Darling River results in water retreating to standing pools. The water in these remnant pools generally has a high electrical conductivity as salts are further concentrated by evaporation. The electrical conductivity of the flows into Menindee Lakes is highly variable, depending on climatic conditions in the upper catchment. High salt loads can result in increased electrical conductivity within Lake Wetherell, adding further complexity to the management of salinity in the Lower Darling. When releases are recommenced, saline water is flushed downstream from the standing pools, where it impacts on water users in the Wentworth weir pool. Monitoring in 2016 has shown that it can take over 50 days for saline water to pass through the weir pool and completely disperse into the Murray River.



A salinity assessment needs to consider land salinity, salt load and stream electrical conductivity in an integrated framework to determine the hazard of a landscape. The Murray Lower Darling salinity technical report (DoIW 2018c) uses the Hydrogeological Landscapes (HGL) framework to undertake an assessment, as well as determine the likely cause and identify solutions. In addition, salinity modelling was used to assess catchment behaviour, define problem areas and quantify impacts. The use of discrete and continuous long term salinity data in these modelling frameworks increased both the accuracy and utility of the salinity models. The salinity assessment in the Murray and Lower Darling valley salinity technical report will inform and give support to the WQMP and identify water, land and vegetation measures to increase productivity and environmental sustainability.

7.2. Elevated levels of suspended matter The draftsman plots show there was generally a linear relationship between turbidity and total suspended solids in the Murray Lower Darling WRPA. Turbidity and suspended sediments were closely related to discharge, with most sites displaying a positive correlation to flow. The lowest turbidity results were in the Murray River upstream of Hume Dam. A large portion of the upper catchment area is National Park, with more than 80% cover by native woody vegetation helping to reduce soil erosion.

Turbidity only increased slightly with distance down the Murray River in response to the cumulative impacts from activities upstream. The Tooma River at Warbrook, Edward River at Deniliquin, Wakool River at Kyalite, Darling River at Burtundy and Murray River at Barham and Lock 8 were all rated as having a high risk to water dependent ecosystems from turbidity in the risk assessment. The highest median turbidity was in the Darling River at Weir 32 and Burtundy. The alluvial soils of the Darling River have a high clay content, which increases their susceptibility to resuspension within the water column. In addition, the very fine clay particles are able to remain in suspension during low and zero flow, maintaining high turbidity readings.

High levels of turbidity are influenced by a number of factors including the wide spread conversion of land for cropping and irrigation, bank and riparian condition, and the presence of carp. Stock trampling causes removal of groundcover, pugging, destabilising soils and erosion of stream banks, which can all lead to increased turbidity (Wilson et al. 2008; Holmes et al. 2009). Carp can contribute to turbidity by stirring up sediments when feeding, uprooting aquatic vegetation, and increasing bank destabilisation (Koehn 2004). Carp are common throughout most of the WRPA.

Rapidly ascending and descending limbs of the hydrograph during irrigation releases, and draw down of water levels in weir pools, can be responsible for channel erosion through bank slumping and bank erosion in the regulated river. To minimise bank degradation, the Murray and Lower Darling water sharing plan lists rates of water level rise and fall, and rates of drawdown in weir pools.

Sites in the Darling River exceeded the turbidity target most years. When the Basin Plan water quality targets were developed, there was insufficient reference data available to develop water quality targets for the middle and lower zones of the Darling River, therefore the default trigger values of the National Water Quality Guidelines (ANZECC and ARMCANZ 2000) were used as the Basin Plan water quality targets. This has resulted in the illogical scenario of water quality targets in the lower reaches of the Darling being more stringent than the upstream reaches. The Basin Plan water quality targets for the Darling upper zone could be applied across the whole Darling River until more appropriate water quality targets are developed.

River Styles® recovery potential (Figure 19) is synonymous with geomorphic condition. Recovery potential represents geomorphic stability and can indicate the capacity of a stream to return to good condition or to a realistic rehabilitated condition (Brierley and Fryirs 2005). Streams rated as having conservation or rapid recovery potential are likely to be the most stable and in a good condition, whereas streams with low recovery potential may never recover to a natural condition or may continue to decline quickly without intervention (Cook and Schneider 2006).

The highest priorities for intervention action are the strategic recovery potential reaches. These are reaches of river that may be sensitive to disturbance, triggering impacts that can have off-site effects. Particular emphasis should be placed on reaches or point-impacts (nick-points), where disturbances may threaten the integrity of remnant or refuge reaches. Figure 21 identifies large portions of the Murray River between Hume Dam and Euston as strategic recovery potential reaches. The Darling Anabranch is also a conservation reach. Proactive



management strategies in these areas are the most effective means of river conservation, leading to improvements in water quality.

There is a short reach of low and moderate recovery potential on the Murray River downstream of Hume Dam. A threat to the recovery potential of this section of the Murray River is the lack of sediment delivered from the upper catchment. Hume Dam acts as a large sediment trap, restricting the movement of sediment down the catchment. As well as providing more suitable conditions within the dam for the production of harmful algal blooms, the reduced sediment load restricts the development of low level benches and bars in the Murray River downstream of Hume Dam, reducing river complexity and the recovery potential.

The Murray catchment upstream of Hume Dam has an extensive network of tributaries identified as conservation reaches. The majority of this area is National Park and State Forest and remains densely vegetated. The recovery potential is decreased in areas cleared for grazing.

There are long reaches in the mid catchment including the Edward River, Wakool River, Niemur River and Merran Creek with low to moderate recovery potential, suggesting sparse riparian vegetation, erosion of the stream bed and stream bank and low instream geomorphic diversity. These reaches are likely sources of suspended sediment.

In the unregulated catchments, land and vegetation management are the key drivers for sediment entering waterways. The principal factor generating high sediment loads (and associated nutrients) is loss of vegetation in the catchment and/or the riparian zone, leading to increased hillslope, gully and bank erosion and increased suspended sediment loads in the river. The main sources of sediment are gully erosion in degraded areas and hillslope erosion where cover is seasonally low through grazing or tillage of cropped lands (National Land and Water Resources Audit 2001). The implementation of flow rules in these catchments will have little impact on reducing sediment inputs. In the regulated system, reducing the extent of bank erosion and slumping may be possible through a more natural, gradual rising and falling limb of water releases from Hume Dam.

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Murr

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Map produced by NSW Industry | Lands & Water | Water December 2018

Data sources: DPI Fisheries,NSW Industry | Lands & Water | Water; Office of Environment and Heritage

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Figure 21: River styles recovery potential in the Murray and Lower Darling Rivers catchment



7.3. Elevated levels of nutrients The highest nitrogen and phosphorus concentrations in the Murray Lower Darling WRPA are in the Darling River at Weir 32 and Burtundy, while the lower results were in the unregulated Murray River upstream of Hume Dam. Nitrogen and phosphorus concentrations generally followed similar trends, indicating similar transport processes are driving both parameters. Nutrient concentrations are generally driven by runoff and erosion during rainfall events, with higher concentrations at high flow.

There are areas of high soil nutrient concentrations in the upper catchment (Figures 22 and 23), which may be contributing to the high nutrient concentrations found in the Tooma River at Warbrook. Soil erosivity and nutrient transport may be exacerbated by the historical conversion of forested land to grazing, particularly clearing in the riparian zone. The Murray River at Barham was rated as a high risk to water dependent ecosystems for total phosphorus and total nitrogen, largely in response to a very high consequence score.

Concentrations of total nitrogen and total phosphorus in the Darling River, above the Basin Plan target, resulted in low WaQI scores for Weir 32 (26) and Burtundy (30). Total phosphorus was deemed to be a medium risk to aquatic ecosystems. The Darling middle, lower zone is a priority area to develop local targets to determine if the low WaQI score at these sites are due to poor water quality, or as a consequence of an inappropriate water quality target. In a similar scenario to turbidity, the nutrient targets decrease between the upper Darling zone and the middle lower Darling zone. Total nitrogen decreases from 900 to 500 µg/L and total phosphorus from 250 to 50 µg/L. The National Water Quality Management Strategy recommends and provides guidance for the development of regional and local targets. New South Wales has not developed targets beyond the default trigger values of the ANZECC Guidelines (2000), and therefore required to use the Basin Plan water quality targets for reporting, or commit to the development of regional or location specific guidelines.

The land use in the Darling catchment is dominated by grazing, with some cropping and irrigation of the lower reaches near Wentworth. Apart from floodplain areas closely associated with the river, most of the soils have low soil nutrient concentrations. This suggests that the bulk of the nutrients are delivered from upstream catchments rather than local sources. Access of livestock to the river may also be a source of nutrients and turbidity.

The fertile soils associated with cropping and irrigation in the lower Murray are a potential source of excess nutrients, though there was not a marked increase in nutrient concentrations with distance downstream. Nutrient impacts can be ameliorated, possibly through a process of assimilation by the river, through phytoplankton uptake and deposition, uptake by benthic organisms or by adsorption onto the sediment of the river bed (Caitcheon et al. 1999).

As for sediment, land and vegetation management are the key drivers for nutrients entering waterways in unregulated rivers. The implementation of flow rules upstream of Hume Dam will have little impact on nutrient management. In the regulated system, reducing the extent of eutrophication caused by bank slumping is possible through a more natural, gradual rising and falling limb of water releases.



Map produced by NSW Industry I Lands & Water 22 August 2018

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Soil Total Nitrogen 0-5cm

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Low : 0.030852

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Geoscience Australia.

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Figure 22: Soil total nitrogen for the Murray and Lower Darling Rivers catchment


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Figure 23: Soil total phosphorus for the Murray and Lower Darling Rivers catchment



7.4. Elevated levels of cyanobacteria Harmful algal blooms have been a regular occurrence in the Murray valley in recent years with extensive blooms in 2009, 2010 and 2016. A number of factors can contribute to the formation of an algal bloom. Nutrient rich inflows, combined with warm, still, clear water during summer, provide ideal conditions for algal growth. Phosphorus and nitrogen concentrations are generally not limiting to algal growth in the Murray Lower Darling WRPA. Harmful algal blooms do occur, but not to the extent indicated by the nutrient concentrations. This highlights that other factors such as flow, turbidity and light availability are also limiting.

The Murray River is highly regulated and subsequently has a range of impediments, creating weir pools. When Hume Dam storage levels fall below six per cent, blooms in the Murray River have been shown to be more likely to occur. It is felt this is a consequence of reduced releases producing lower velocity flow in the river and/or algal blooms in Hume Dam itself, seeding the river (Baldwin et al 2008, 2009). Lake Mulwala has also been found to seed the river downstream with algae, once a bloom develops. The release of large volumes of water for irrigation over summer results in turbulent, high velocity water which is not suitable for algal growth. High flow releases have generally not been an available management option during algal blooms in the Murray River, as they have occurred during periods of prolonged drought. In all cases it has been a matter of waiting for cooler weather, rain, increased run-off or strong winds to cause the blue-green algae to dissipate, or for the bloom to disperse naturally with time.

Red alerts for recreational use are also common in Menindee Lakes and in the lower Darling River. A discharge of 300 ML/day from Menindee Lakes was found to be sufficient to prevent prolonged periods of persistent thermal stratification, which also suppressed the development of algal blooms. Mitrovic et al. (2011) also found a flow release of 3 000 ML/day was effective at removing an established cyanobacterial bloom. As well as flushing algae downstream, greater discharges increased turbidity, which diminished the growth of cyanobacteria through reduced light availability.

Seeding by Hume Dam was determined to be the major cause of the 2009 bloom. A similar situation occurred downstream of Lake Mulwala, with algal rich water released into the Murray River downstream and diverted into the Mulwala Main Canal. As both Lake Hume and Lake Mulwala were infested with cyanobacteria, there was no clean, non-infested water available to provide flushing flows downstream. Blooms in the mid-section of the Murray River downstream of Torrumbarry Weir through to Euston Weir may have developed in-situ, as a result of the low flow conditions and low water levels increasing residence times in this section of the river.

A combination of nutrients, sunlight, high water temperature, minimal rainfall and still water were proposed as the likely causes of the 2016 bloom, in addition to the release of algal infested water from Lakes Hume and Mulwala (Bowling et al. 2016). The 2016 bloom was unique in that the species composition was comprised predominately of Chrysosporum ovalisporum. The optimal water temperatures for this species are normally 25 to 30°C, but river temperatures during the bloom were not generally this high. Blooms containing C. ovalisporum have been recorded in NSW previously, but these have been small, and the species was not dominant. Most reported blooms of this species have produced the toxin cylindrospermopsin, but the Murray bloom appeared to have been non-toxin producing. Reviews of meteorological, hydrological and water quality data did not provide any obvious reason why this species bloomed at this particular time (Bowling et al. 2016).

Similar to the 2009 bloom, the release of water from upstream to flush algae from the system was not an option due to the lack of clean, non-infested water available to provide flushing flows, and the large extent and severity of the bloom.

Nutrient management in the catchment area of Hume Dam is essential to reduce the risk of algal blooms within the dam. When algal blooms do occur, the level of human exposure can be reduced by implementing the established algal management framework. The NSW Algal Management Strategy and implementation of the Murray and Sunraysia Regional Algal Contingency Plans, are instrumental in ensuring the public health aspects are met. The Murray Regional Algal Coordinating Committee is administered by WaterNSW and includes representatives from NSW Health, NSW Department of Industry Water, Victorian Department of Environment, Land and Water Planning, NSW Office of Environment and Heritage, NSW Department of Primary Industries, Local Land Services, Murray Irrigation Limited, Goulburn-Murray Water, Lower Murray Water, NSW Local Government and the MDBA. The risk at a site with a high recreational usage can be



reduced via implementing the management strategies of erecting algal warning signs and informing users of the health risks, dangers and symptoms of ingesting or coming into contact with blue-green algae.

7.5. Water temperature outside natural ranges Preece (2004) characterised storages across New South Wales according to their level of impact due to thermal (cold water) pollution. Hume Dam was identified as likely to cause severe cold water pollution in the Murray River, largely due to discharges in the order of 20 000 ML/day during summer. The outlet works of Hume Dam comprise intakes at 30 to 34 m below full storage level. Walker (1980) found the water temperature downstream of Hume Dam to be approximately 3°C lower than upstream of the storage. Due to the large releases, cold water pollution will generally persist for 200 km to the headwaters of Lake Mulwala (Walker 1980).

During most summers, the water temperature downstream of Hume Dam was close to the 20% percentile of the upstream reference site at Jingellic. An impact can be observed in 2012 and 2013. The water temperature downstream is 3 to 5°C colder than the upstream reference site during the summer months. The cold water impact decreases with distance downstream, but is still evident at the Corowa gauging station. It is expected that impacts would extend to Lake Mulwala. Hume Dam filled to 100% following heavy rainfall in 2010 and remained above 90% capacity for most of 2011 and 2012. The greater depth of water above the offtakes results in increased cold water pollution. The impact is not as prononuced during the 2014 to 2016 summer releases. As the storage volume and the depth of water above the outlets decreased over the following years, the impact was not as pronounced.

The thermal pollution WaQI score, using the difference between the reference site and downstream data was 42, which is a poor rating. In addition to cold water pollution, the poor WaQI rating was also a consequence of warmer water released during winter.

Cold water pollution can hinder ecological responses in the Murray River downstream of Hume Dam. The issue of thermal pollution cannot be mitigated in the Murray WRPA through the use of flow rules in the WRP, environmental flows or by making adjustments to release patterns. Major infrastructure works, such as a multi-level offtake or thermal curtain are required.

7.6. Dissolved oxygen outside natural ranges The dissolved oxygen levels at most sites was within the target range for the majority of the data period. During low and cease to flow periods, dissolved oxygen levels become unpredictable and fluctuate from very high to very low. These variations are primarily driven by the response of instream biota in these rivers. High organic carbon, nutrients and water temperatures result in increased microbial respiration. High turbidity and suspended sediment reduces light availability, and likely reduces primary production. The lowest annual median dissolved oxygen results were in the Darling River at Weir 32 and Burtundy. A combination of low flow, high turbidity and warm water temperature can result in low dissolved oxygen levels at these sites.

The Murray River downstream of Yarrawonga Weir monitoring site is located approximately 250 metres downstream of the weir. The release of water from Yarrawonga Weir could result in low dissolved oxygen results downstream. As the annual median was above 100% saturation most years, suggests this is not the case. Similarly the Murray River at Lock 8 monitorinf sites is located downstream of the weir. The progression of water through the weir, and possible aquatic plant growth within the weirs appears to oxygenate the water.

Maintaining low and base flows through cease and commence to pump rules and protection of small freshes in unregulated catchments assist in flushing or turning over stratified pools. This breaks down the stratification and prevents water on the bottom of pools becoming anoxic and unsuitable for aquatic fauna. In addition, flows help prevent excessive algal and aquatic macrophyte growth which can result in supersaturated oxygen conditions.

The Murray is a controlled river. The regulation of flows via dams, weirs and locks reduces the frequency of flooding in return for better security for town water supply and agriculture. The retention of peak winter/spring flows in Lake Hume for later water delivery reduces the frequency of floodwater breaking the banks, and flowing onto the floodplain. Numerous dry years preceding 2010 meant that regular flooding of the valley had



been further reduced. During the spring and summer of 2010-2011, there were several large flow events that led to widespread flooding of the floodplain, some of which had experienced little recent inundation. This resulted in a large-scale hypoxic blackwater event in the southern Murray–Darling Basin that affected over 2 000 km of river channels and persisted for six months (Whitworth et al. 2012). Further flooding in August 2016 led to an additional hypoxic blackwater event.

Hypoxic (no oxygen) blackwater is a natural feature of lowland river systems, and occurs during flooding when organic material (sticks, leaves, bark and grass) is broken down in the flood water, or is washed off the floodplain, and into the river. The breakdown of this material by bacteria can lead to a sudden decrease in the oxygen available to fish and other organisms. The critical minimum level for dissolved oxygen varies between fish species, their size and their physical condition. The larger the fish, the more oxygen they require. As a general guide, native fish and other large aquatic organisms require at least 2 mg/L of dissolved oxygen in water to survive, but may begin to suffer at levels below 4 to 5 mg/L (Gerhke 1988). The black appearance of the water is due to the release of dissolved carbon compounds, including tannins, as the organic matter decays. Large blackwater events can lead to fish kills and ecosystem collapse (Whitworth et al. 2012).

The extent of the impact that hypoxic blackwater events have on a river is also affected by water temperature. At high water temperatures, there is naturally less dissolved oxygen in the water, and the breakdown of carbon occurs more quickly, making hypoxia more likely to occur. In cooler weather, organic carbon can stimulate productivity in the food chain, but the dissolved oxygen is not consumed so quickly that the water becomes hypoxic. The impact of a hypoxic blackwater event on the river ecosystem can change as the flood water moves downstream. Often the effects of an event can be less severe as flows progress down the catchment.

Hypoxic blackwater events can be particularly severe in the Edward-Wakool system. This system is downstream of both the Barmah-Millewa Forest and Koondrook-Perricoota Forest. During flood events, the Wakool River receives water with high dissolved carbon that is returned from both of these floodplain forests, in addition to carbon entering the river from localised overbank flooding within the Edward-Wakool system.

It is not possible, nor desirable, to prevent hypoxic blackwater events from occurring, as they usually extend over a large area. Hypoxic blackwater events on this scale have occurred in the past, and will continue to occur in the future. It is distressing that these events occur, resulting in the loss of fish and other aquatic life. The impacts of these events on the environment are harmful, but are usually short-term, as the river water re-oxygenates again as the flooding subsides. Naturally occurring events such as these underpin the broad health of rivers. They provide nutrients to drive the overall production of our river and wetland systems. In the longer term, native fish, water birds and other organisms will benefit from the increased production in the river, boosting food supplies and supporting breeding cycles.

It may be possible to reduce the duration and/or severity of hypoxic blackwater events through more frequent flushing of forests and floodplains in winter and early spring, when water temperatures are lower. This will help remove some of the carbon load, so the carbon inputs during subsequent floods will be lower and more likely to result in good outcomes for river ecosystems.

The dilution of blackwater returning to the river from the floodplain, using better quality water released from upstream, has proven to be a successful management approach. These releases provide refuge areas of higher dissolved oxygen for native fish and other aquatic species to congregate until the blackwater event has passed. The Murray Lower Darling Environmental Water Advisory Group (MLD EWAG) in consultation with the Technical Advisory Group determines when and how environmental water is to be released to try and achieve a specific ecological goal or to avoid/mitigate environmental risks wherever possible. The groups also try to predict the likelihood and severity of an event occurring, monitor to detect if an event is occurring and its extent and then respond with the available strategies to help mitigate the effects. The MLD EWAG includes representatives from Local Land Services, Forestry Corporation of NSW, Department of Primary Industries, the Centre for Freshwater Ecosystems, recreational fishing groups, landholder representatives, Murray-Darling Wetlands Working Group, Murray Lower Darling Rivers Indigenous Nations, Office of Environment and Heritage and WaterNSW. The group also includes observers from the Commonwealth Environmental Water Holder and Murray-Darling Basin Authority.

The volume of environmental water available in Lake Hume is not sufficient to flush organic material from the entire floodplain. Instead, environmental water can be used to produce the small floods to flush material from lower areas. Studies undertaken by the Murray Darling Freshwater Research Centre suggest delivering



environmental flows to forest areas in winter or early spring, when water temperatures are lower and the risk of triggering a hypoxic blackwater event is reduced.

Recommendations to improve prediction and management of hypoxic events (DPIW 2013) include:

Development of a monitoring plan ahead of expected hypoxic events;

Better hydrological knowledge of floodplain returns, with a combination of time series flow data at points along the river, better ratings data from escapes and adequate gaugings at major floodplain escapes during events;

Comprehensive dissolved oxygen time series monitoring;

Comprehensive dissolved organic carbon monitoring before, during and following events, and

Increased use of existing blackwater models to enable better validation and enhance prediction.

The Basin Plan dissolved oxygen target ranges were designed specifically to be applied to monthly data, and provide an indication of any issues. Monitoring of dissolved oxygen is currently conducted monthly, however it does not capture the full diurnal variation. To fully capture dissolved oxygen dynamics, continuous monitoring during a range of hydrologic and seasonal conditions is required. Dissolved oxygen sensors have been installed at key gauging stations in the Murray and Lower Darling catchment as a tool to better monitor blackwater events. The use of continuous data may prove more beneficial for assessing dissolved oxygen concentrations than single monthly readings. Watson et al. (2009) suggests that when dissolved oxygen concentrations drop below 5 mg/L (or 50% saturation) in lowland rivers, there is a substantial increased risk to fish health. This target has been applied in the Basin Plan for managing water flows (Section 9.14 (5)). It was proposed by Tiller and Newall (2010) that the assessment of continuous data against this proposed trigger level may prove more beneficial for dissolved oxygen data analysis and give a better assessment of the oxygen regime.

7.7. Elevated levels of pesticides and other contaminants Historically, monitoring of pesticide residues in rivers has not been undertaken in the Murray and Lower Darling Rivers. With the agricultural industry becoming increasingly reliant on chemical use for weed and pest control, it is expected that the residues of some chemicals may be present in waterways. The detection of residues of herbicides used in dryland agriculture in other valleys has shown a need for natural filters such as grassed waterways, natural grasslands or vegetated buffer strips to reduce chemical concentrations in runoff and aerial drift.

There are no current monitoring data on the presence of toxicants in this water resource plan area. Pollution from mining and industrial activities is controlled through environmental protection licences under the Protection of the Environmental Operations Act 1997 (POEO Act).

7.8. pH outside natural ranges Soil pH increases with distance down the Murray River catchment (Figure 24), but this is not reflected to the same extent in the water quality results. There was a slight increase in the annual median with distance downstream, with the highest results in the Murray River at Merbein Pump Station. The soils in the Darling River catchment are alkaline which could be causing the high pH results at Weir 32 and Burtundy, above the Basin Plan upper limits. The pH in the Darling River sites was also correlated to dissolved oxygen, suggesting elevated pH could be driven by primary productivity, such as increased algal growth.




! Towns

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Soil pH 0-5cm

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Low : 3.65925

Data Sources:





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!

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KHANCOBAN

BROKEN

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BARHAM

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TUMBARUMBA

DENILIQUIN

MURRAY AND LOWER DARLING WATER RESOURCE PLAN AREA- SOIL pH

Mur

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Figure 24: Soil pH for the Murray and Lower Darling Rivers catchment

7.9. Elevated pathogen counts There are no current data on the extent of pathogens in the Murray Lower Darling WRPA. It is expected that with ongoing inputs of human and animal waste, and access of stock and animals to rivers and streams, that pathogens would be present in waterways. Higher counts would be expected following rainfall and runoff flushing contaminants into the rivers, and during the warmer summer months. Similarly, high counts may be common during low flows in areas with point source pollution. There is an unknown risk from the high prevalence of septic systems across the catchment. As for other pollutants, pathogens cannot be managed through water planning.

7.10. Knowledge gaps Dissolved oxygen

Dissolved oxygen is currently not monitored immediately downstream of Hume Dam. It is anticipated that water drawn through the low level outlets would have very low dissolved oxygen levels. It is not known if turbulence from the process of releasing the water from Hume Dam re-oxygenates the water as it enters the river. Or, how far downstream the water needs to flow before it becomes oxygenated to a level suitable for aquatic organisms.

Water temperature

Clearing of vegetation in the riparian zone and poor geomorphic condition can lead to increased sunlight reaching the water surface, resulting in increased water temperatures. The extent and scale of this form of increased thermal pollution is unknown.

Event based monitoring

The current surface water quality monitoring program targets low and base flow conditions with limited, high flow event based monitoring. High velocity water is generally required to transport large concentrations and loads of suspended sediment and associated nutrients, pesticides and pathogens. Suspended solids and



nutrients tend to increase during high river flow, when particulate matter is washed from the catchment, bank erosion contributes material and/or bed sediments are resuspended in the water column. The high velocity water in the upper catchment is capable of carrying greater quantities of sediment and nutrients. As the stream bed flattens out across the floodplain, these nutrient rich suspended particles fall out of suspension and are deposited on the floodplain and into river sediments. For streams upstream of Hume Dam, this material is deposited in the dam, settling out of the water column and providing a source of nutrients to sustain algal blooms. The deposition of sediment in the dam results in less material for instream bar and bench formation downstream.

Hazard mapping

Spatial modelling to develop hazard mapping, utilising the range of data sets available such as, riparian vegetation cover and geomorphic condition, and overlaying soil erosion risk areas, soil nitrogen and soil phosphorus, could identify key areas most likely to contribute to poor water quality and guide the implementation of management decisions. In addition, the mapping and identification of high priority refuge pools would assist in the monitoring and delivery of water to maintain water quality suitable for water depended ecosystems during extended dry periods.

Additional water quality monitoring sites

The current New South Wales surface water quality monitoring program has been in operation since 2007. It was established and designed to meet the objectives and data requirements at the time. A revision of the state wide water quality monitoring program is required to better meet the requirements of the Basin Plan and to fill identified information gaps.

Agricultural chemical, toxicants and pathogen data

There are no current data on the concentrations of agricultural chemicals in the creeks and rivers of the Murray Lower Darling WRPA. As large quantities of insecticides and herbicides are used in the catchment, and the main transport mechanisms for their movement in the environment still exist, it is assumed that there is a risk that chemical residues are present in waterways. Without monitoring data, we cannot determine which chemicals are present, when, or the concentrations. Similarly, it is only assumed that there are pathogens present in the waterways.

Development of local water quality targets

It has been identified that some of the Basin Plan water quality targets may not be appropriate for some parameters, in some zones. The Middle and Lower Darling zone is the highest priority for target development, along with assessment of the suggested boundary change to remove the Edward–Wakool system from the central Murray zone. Time frames do not allow for the development of local targets before the completion of the WQMP, but they will be incorporated as a long-term strategy in the plan.

8. Conclusion The quality of the water in a river or stream is a reflection of underlying climate and geology and the multiple activities occurring in a catchment area. There are numerous factors contributing to the observed results, many of which are outside the influence of flow management and therefore cannot be addressed through water planning alone.

In unregulated catchments, greater emphasis must be focused on preventing pollutants such as sediment and nutrients from entering waterways through land, soil and vegetation management. As sediment is a major transport mechanism for many pollutants, practices such as maintaining groundcover, vegetated buffer strips and good agronomic practices together with management of riparian vegetation to reduce stream bank erosion provide simple and effective means to improve water quality. Land and vegetation management does not only address water quality issues in the rivers but also harmful algal blooms in Hume Dam, Menindee Lakes and the Murray River.

In the regulated system, issues of dissolved oxygen, contribution of sediment and nutrients through bank slumping, dissolved organic carbon and to a lesser degree, cold water pollution can be addressed through the implementation of flow rules.



There are opportunities for government agencies, including NSW Local Land Services (LLS), Office of Environment and Heritage (OEH), DPI Fisheries and DPI Agriculture to work closely with Department of Industry, Water in managing external constraints through complementary measures. Collaboration between natural resource management groups to examine alignment of priorities has been a continued focus of NSW Government (NRC 2010). Alignment of natural resource management continues to be identified as a priority for LLS (Local Land Services 2016) and for the management of environmental water and water quality in New South Wales (OEH 2014). Alignment of priorities for river management will assist in strengthening the outcomes of mitigation measures.

The information and data analysis from this report will support the development of the Murray Lower Darling Water Quality Management Plan (WQMP). Based on the water quality data and information available, water quality objectives for the Murray Lower Darling WRPA will be formulated where there are flow ‘levers’ available to water managers. The WQMP will consider the impacts of wider natural resource and land management on water quality within the Murray Lower Darling water resource plan area. It will provide a framework to protect and maintain water quality that is ‘fit for purpose’ for a range of outcomes. These uses and activities may include irrigation of crops, maintaining a healthy environment, recreational fishing or cultural and spiritual links to Country for Aboriginal communities.



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Sherman B., Todd C.R., Koehn J.D. and Ryan T. 2007. Modelling the impact and potential mitigation of cols water pollution on Murray cod populations downstream of Hume Dam, Australia. River Research and Applications 23: 377-389.

Smith, V.H., S.B. Joye, and R.W. Howarth. 2006. Eutrophication of freshwater and marine ecosystems. Limnology and Oceanography: 351-355.

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Sposito, G., and S. V. Mattigod. 1977. On the chemical foundation of the sodium adsorption ratio. Soil Science Society of America Journal 41: 323-329.

Srebotnjak, T., G. Carr, A. de Sherbinin, and C. Rickwood. 2012. A global Water Quality Index and hot-deck imputation of missing data. Ecological Indicators 17: 108-119.

Steele, M., and J. Odumeru. 2004. Irrigation water as source of foodborne pathogens on fruit and vegetables. Journal of Food Protection 67: 2839-2849.

Terrado, M., D. Barceló, R. Tauler, E. Borrell, and S. de Campos. 2010. Surface-water-quality indices for the analysis of data generated by automated sampling networks. TrAC Trends in Analytical Chemistry 29: 40-52.

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Appendix A. Water quality monitoring site locations Table 25: Location of water quality monitoring stations in the Murray Lower Darling WRPA

Station Number

Station Name Latitude Longitude

Routine water quality

401556 Murray River at Indi Bridge -36.235100 148.035100

401003 Tooma River at Warbrook -36.044600 148.037900

401201 Murray River at Jingellic -35.929200 147.704100

409001 Murray River at Albury (Union Bridge) -36.091800 146.906800

409025 Murray River d/s Yarrawonga Weir -36.010100 145.997110

409003 Edward River at Deniliquin -35.529700 144.965700

409013 Wakool River at Stoney Crossing -35.037680 143.570500

409034 Wakool River at Kyalite -34.949701 143.481024

409005 Murray River at Barham -35.630400 144.123500

414209 Murray River upstream Euston Weir -34.599700 142.758600

414206 Murray River at Merbein Pump Station -34.173343 142.082577

425012 Darling River at Menindee Weir 32 -32.436903 142.379985

425007 Darling River at Burtundy -33.743683 142.270868

42610001 Murray River at Lock 8 -34.128507 141.399365

Blue-green algae


409026 Mulwala Canal at Offtake -35.982100 146.010700

409025 Murray River d/s Yarrawonga Weir -36.010100 145.997110

409202 Murray River at Tocumwal -35.812820 145.559113

40910089 Murray River at Picnic Point -35.854443 144.998876

40910087 Murray River at Moama (Echuca) -35.120392 144.755067


41310021 Murray River at Mount Dispersion -34.591176 142.471563


40910090 Edward River at Old Morago -35.379874 144.653815

409014 Edward River at Moulamein -35.089900 144.033100

409015 Gulpa Ck at Mathoura -35.815147 144.917951

409045 Wakool River at Wakool-Barham Road -35.510500 144.209900

409034 Wakool River at Kyalite -34.949701 143.481024

Continuous electrical conductivity

409016 Murray River downstream Hume Dam (Heywoods) -36.099100 147.024000

409002 Murray River at Corowa -36.007200 146.395300

409025 Murray River downstream Yarrawonga Weir -36.010100 145.997110

409029 Mulwala Canal at Edward River -35.564500 145.008300




409008 Edward River at Offtake -35.847900 144.997900


409023 Edward River downstream Stevens Weir -35.434400 144.758600

409035 Edward River at Leiwah -34.988800 143.622800


409207 Murray River at Torrumbarry -35.942583 144.464667

409214 Murray River at Pental Island Pumps -35.423556 143.764778

409204 Murray River at Swan Hill 35.327639 143.564167

414203 Murray River at Euston -34.600250 142.758194

414216 Murray River downstream Mildura Weir -34.168139 142.160083

425012 Darling River at Weir 32 -32.436903 142.379985

425005 Darling River at Pooncarie -33.386400 142.567800


A4260501 Murray River at Lock 9 -34.191613 141.595565

Continuous water temperature

401012 Murray River at Biggara -36.319200 148.051900

401013 Jingellic Creek at Jingellic -35.895800 147.692700

401201A Murray River at Jingellic -35.929200 147.704100

409016 Murray River downstream Hume Dam (Heywooods) -36.099100 147.024000

409017 Murray River at Doctors Point -36.112300 146.939900


409037 Murray River at Howlong -35.976400 146.619600

409002 Murray River at Corowa -36.007200 146.395300

409025 Murray River downstream Yarrawonga Weir -36.011400 145.994000

409008 Edward River at Offtake -35.847900 144.997900

Continuous dissolved oxygen


409047 Edward River at Toonalook -35.642800 144.959600


409014 Edward River at Moulamein -35.089900 144.033100

409062 Wakool River at Gee Gee Bridge -35.329000 143.932200


409048 Niemur River at Barham – Moulamein Road -35.273900 144.159500

409086 Niemur River at Mallan School -35.135100 143.800100

409044 Little Merran Creek at Franklins Bridge -35.521400 144.051700

409036 Merran Creek upstream Wakool River Junction -35.107400 143.582600

409111 Barber Creek at Sandy Bridge Road -35.506862 144.078137




Appendix B. Water quality index (WaQI) method A water quality index is a tool to communicate complex and technical water quality data in a simple and consistent way. It is useful for presenting information with different units (e.g. µg/L and % saturation) or characteristics (e.g. turbidity in a montane vs lowland river) on a common scale. It can also be used as a reporting tool for evaluation of changes in water quality over the life of a water quality management or water sharing plan.

For water quality management plans (WQMP) the WaQI is calculated as an overall integrated index (for five to eight parameters) and for each water quality parameter individually. These calculations are performed independently.

The overall WaQI for the WQMP includes total nitrogen, total phosphorus, turbidity, dissolved oxygen and pH. It is based on the exceedance of water quality targets as prescribed in Schedule 11 of The Basin Plan. Blue-green algae, salinity and temperature are calculated as individual parameters. To calculate the index a minimum of 30 samples is required across a five year period with a minimum of four samples in any one year.

The outcome provides a number between 1 and 100 that is categorised according to the following:

The index for both the overall score or, for an individual parameter is calculated as:

√𝐹12 + 𝐹22

𝑊𝑎𝑄𝐼 = ( )1.41421

Where F1 (frequency), the frequency of the number of failed tests per total tests, is:

𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑓𝑎𝑖𝑙𝑒𝑑 𝑡𝑒𝑠𝑡𝑠 𝐹1 = ( ) × 100

𝑇𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑒𝑠𝑡𝑠

And where F2 (amplitude), the amplitude is the amount a value exceeded he target, is:

𝐹2 = (𝑛𝑠𝑒 ÷ [0.01𝑛𝑠𝑒 + 0.01])

Where nse (the normalised sum of excursions) is:

𝑛∑𝑖=1 𝑒𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛 𝑖 𝑛𝑠𝑒 = ( )

𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑒𝑠𝑡𝑠

And where the excursion is:

𝐹𝑎𝑖𝑙𝑒𝑑 𝑡𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒 𝑖 𝐸𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛 = (

𝑇𝑒𝑠𝑡 𝑜𝑏𝑗𝑒𝑐𝑡𝑖𝑣𝑒 )

or

𝑇𝑒𝑠𝑡 𝑜𝑏𝑗𝑒𝑐𝑡𝑖𝑣𝑒 𝐸𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛 = ( )

𝐹𝑎𝑖𝑙𝑒𝑑 𝑡𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒 𝑖



How was the method determined?

A literature review of existing water quality index methods, purposes and reviews was conducted in 2015. There is extensive literature (over 500 papers), and a wide range of existing methods (more than 100) of calculating water quality indices. A number of individual index methods as well as key text and review papers (e.g Abbasi and Abbasi 2012; Achterberg 2014; Bauer et al. 2013; Brown et al. 1970; Cude 2001; Dinius 1987; Hurley et al. 2012; Lumb et al. 2011; Srebotnjak et al. 2012; Terrado et al. 2010; Van Oost et al. 2007) were reviewed to determine an appropriate index for NSW that is robust and meets our requirements.

The Canadian Council of Ministers of the Environment (CCME) water quality index (Roulet and Moore 2006) was chosen as method on which to base the WaQI. The key questions that were considered when making this decision were:

Has it been tested and accepted in peer review literature?

How widely is it used?

Can it be used without requiring calibration to biogeographically distinct regions?

Is it flexible, and can it be used with continuous data or toxicants if required?

Has it been tested against ecological indices (e.g. macroinvertebrates)?

Can it be easily presented and understood for reporting?

The method has been modified to remove a subindex that included the number of failed parameters. The subindex was excluded as only five to seven parameters will be used to calculate the NSW WaQI. In comparison, the CCME WQI is designed for up to +30 parameters.



Appendix C. Literature Review A Web of Science search was undertaken that always included ‘NSW’ and then one of the following ‘Murray River’, ‘Darling River’, ‘Edward River’, ‘Wakool River’, ‘Hume Dam’, or ‘Dartmouth Dam’. This search was supplemented with a search using the Google Scholar database and the terms ‘Murray’, ‘Darling’, ‘river’ and ‘NSW’. The output is summarised in Table 26.

Table 26: Review of published literature

References Subcatchment Description

Korbel and

Hose 2015

Alluvial Found water quality appeared to have relatively little influence on stygofauna.

Some influence on microbial communities. Water flow and habitat appeared

most important for stygofauna.

Macdonald et

al. 2012

Lowlands Flooding supports recruitment for weeds. Recruitment reduced by presence of

other vegetation. Hotter constant temperatures reduced germination.

Fluctuation and colder temperatures increases germination.

Kingsford 2000 Wetlands Water quality has had an effect on river red gum survival. Also studied the

Macquarie, Barmah, Millewa and Moira Marshes and Chowilla floodplain.

Brock et al. Narran Lakes, Tested response to zooplankton hatching and seed germination to different

2005 Gwydir

wetlands,

Macquarie

Marshes,

Billybung

Lagoon, Lake

Cowal, Great

Cumbung

Swamp, Darling

anabranch

salinities in a range of wetlands. Salinity increases in soils when damp but not

when flooded. Aquatic plant germination and species richness decreased

significantly with increasing salinity. These decreases started immediately

between the lowest treatments of <300 to 1000 mg/L. Similar for zooplankton

hatching, Macquarie Marshes had significant declines above <300 mg/L,

Narran Lakes and Gwydir had declines above 1000 mg/L. Community structure

changed above 1000 mg L Increased salinity however had no effects on Lake

Cowal, Darling Anabranch and Great Cumbung Swamp (ie up to 5000 mg/L

treatment). There was no change in community structure.

Kelleway et al.

2010

Wetlands Carbon sources supporting consumers are varied and appear related to spatial

distribution of primary producers. Highlights the importance of riparian

vegetation as a carbon source, its influence on shading and decreases in in-

channel solar radiation limiting in-channel autotrophic production.

Norris et al. Murray and Habitat condition is degraded across much of the basin. Loss of riparian

2001 Lower Darling

(and all of Basin)

vegetation and increased sand and gravel bed load are the principal

components causing degradation. Most marked degradation is in the mid

slopes.

Nutrient and sediment loads from the Australian Alps are largely unmodified. Most of the loads are generated in the upland and mid-slope areas while most of the impact is felt in lowland rivers, weir pools and reservoirs where the sediment is stored. In the long-term, management needs to focus on reducing sediment supply, but the greatest short-term benefits will come from managing the lowland sediment and nutrient stores.

Parts of the Murray River are extremely impaired, with 43% of the Murray

Riverina area and 19% of the Darling River substantially modified. Parts of the

Murray River may have lost over 80%of the biota likely to have occurred there.

Rolls et al.

2013

Lowlands,

midlands

Temperature, flows, habitat and food resource (prey size and availability) all

impair fish recruitment. Flow magnitude and water temperature appeared to

have the largest effect in determining larval fish composition. Hypothesised that



a lack of prey and resources may be one of the reasons why there is not a

strong response to managed flow events.

Erskine et al.

2012

Lowlands Studies the importance of in-stream woody debris to protect against erosion

and restore river health.

Austin et al.

2010

Murray and

Darling (and all

of Basin)

Estimates that climate change my reduce water yield in the Upper Murray River

by over 18% by 2030 and 43% by 2070, the Murray-Riverina by over 21% by

2030 and 48% by 2070, and Darling River by over 26% by 2030 and 57% by

2070. These numbers are based on the higher resolution model of two

scenarios tested. This scenario is overly optimistic and assumes wide spread

change in energy production industry towards less emissions intensive.

Woodward et Midlands Examined carbon and nutrient inputs from banks under different flow heights.

al. 2015 Where river channels have already been impacted by regulated flows, complex

surfaces may have been lost, so restoring more natural flows at these levels of

channel, may have little immediate impact on nutrient processing. Low level

benches will need to be ‘rebuilt’ before environmental flows can increase connectivity.

NSW DPI, 2006 Weir review,

Murray River

Detailed review of weirs in the Murray River catchment providing a

comprehensive overview of each structure including operational details, system

hydrology, ecological considerations, and the preferred remediation option of

NSW DPI for improving fish passage at the weir.

Ryan et al. Murray River High concentrations of cyanobacteria were detected by routine monitoring in

2009 Lake Hume in March 2009, resulting in the issuing of a red alert for recreational

use. Following the detection of the bloom in Lake Hume, additional

downstream monitoring indicated that cyanobacteria was present in the Murray

River for a distance of 1 000 km, including associated tributaries of Gulpa

Creek, Edward River and Wakool River.

Sherman 2005 Hume Dam Discharge temperatures from Hume Dam during spring and summer may be

depressed by more than 5°C relative to the temperature in the surface layer of

the reservoir. Hume Dam receives water from Dartmouth Dam via the Mitta

Mitta River and from the Snowy Hydro Scheme via the River Murray. Both of

these sources may deliver unseasonably cold inflows to Hume Dam.

Two options proposed for mitigation of cold water pollution: construction of a multi-level offtake or deployment of a submerged curtain. The submerged curtain option was expected to produce the greatest discharge temperature.

Sherman et al

2007

Hume Dam Mitigation of cold water pollution through the introduction of selective

withdrawal capabilities to access near-surface water is predicted to increase

discharge temperatures during the crucial spring-early summer post-spawning

period by 4–6°C for normal operating conditions. No improvement in discharge

temperature was predicted for drought conditions characterised by relatively

low storage levels in early spring. The predicted temperature increase using

selective withdrawal increased the predicted average minimum female

population abundance by 30–300%. Increased discharge temperatures appear

to be achievable and are expected to reduce the stress currently impacting

Murray cod populations during crucial post-spawning periods. This provides

evidence that mitigation of this problem may assist in rehabilitating Murray cod

populations in the Murray River downstream of Hume Dam.

Whitworth et al

2012

Southern Murray

Darling Basin

After a decade long drought in south-eastern Australia, a series of spring and

summer flood events in 2010–2011 resulted in a large-scale hypoxic

blackwater event in the southern Murray–Darling Basin that affected over

2000 km of river channels and persisted for six months. Inundation of both



forested and agricultural floodplains that had not been flooded for over a

decade mobilised large stores of reactive carbon. Altered flow seasonality, due

to a combination of climatic effects and river regulation, not only increased the

risk of hypoxic blackwater generation, but also shifted the proportion of

bioavailable carbon that was returned to the river channels. Hypolimnetic weir

discharge also contributed to hypoxia at some sites.

Mitrovic et al.

2011

Lower Darling Flow releases from the regulated Menindee Lakes System were assessed for

their ability to either suppress bloom development or to mitigate pre-existing

blooms over this period in the Darling River at Weir 32. A discharge of

300 ML/day (flow velocity of 0.03 m/s) was found to be sufficient to prevent

prolonged periods of persistent thermal stratification, which also suppressed

the development of Anabaena circinalis blooms. A flow release of 3000 ML/day

was effective at removing an established cyanobacterial bloom, and total

cyanobacterial numbers declined from over 100 000 to 1 000 cells/mL within a

week.

In two summers without blooms, higher flows and decreased light availability

prevented the development of cyanobacterial blooms. Flow releases were

effective at mitigating cyanobacterial growth through either the suppression of

persistent thermal stratification or through dilution and translocation of cells.

Greater discharges also increased turbidity, which diminished the growth of

cyanobacteria through reduced light availability under the mixed conditions,

which also reduced the ability for surface migration through buoyancy

regulation.

Bowling et al.

2016

Murray River An unusual bloom of Chrysosporum ovalisporum occurred in the Murray River

from mid-February to early June 2016. At its greatest extent in April and May it

extended along the river from Lake Hume to Lock 8 and also throughout the

Edward, Wakool and Niemur River distributary system, a combined river length

of about 2360 km. It also extended into distributary systems in Victoria. Bloom

densities at times exceeded 40 mm3/L, and C. ovalisporum usually comprised

>99% of the total bloom biovolume at most locations sampled. The origins of

the bloom were most likely Lakes Hume and Mulwala on the upper Murray

River, with cyanobacterial infested water released from them contaminating the

river systems downstream.

Thoms et al. Darling River In the Great Darling Anabranch, the fish community is dominated by carp as

2000 there is little habitat available for native fish except during floods. Riparian

vegetation is in poor condition as a result of clearing in the past. Grazing has

affected the regeneration of vegetation on the floodplain to some extent.

Parsons et al.

2008

Murray Darling

Basin

Generally the river systems in the upper Murray remain relatively fresh.

However salinity in the lower Murray (the Mallee region), in particular below the

South Australian border, can approach critical levels. There is a delicate

balance in the interface between the groundwater regime and the river regime.

The river varies between being a losing stream and a gaining stream.

Gilligan and Carp abundance in the upper Murray River was relatively low compared to

Rayner 2007 other Murray-Darling Basin catchments in NSW. Except for Lake Hume itself

and wetlands on the upper Murray floodplain, carp are unlikely to have a

substantial impact on turbidity and sediment re-suspension given the low

proportion of muddy substrates susceptible to re-suspension. Low carp

abundances in upstream areas are linked to unsuitable habitat and water

quality conditions (colder winter temperatures).



Appendix D. Water quality summary statistics Table 27: Water quality summary statistics for the Murray Lower Darling WRPA 2007-2015 water quality data

Total Nitrogen (mg/L)

Total Phosphorus (mg/L)

Site Name N Mean Std Dev Std Error Min Q10 Q25 Median Q75 Q90 Max

Murray River at Indi Bridge 88 0.206 0.205 0.022 0.060 0.110 0.130 0.165 0.215 0.290 1.900

Tooma River at Warbrook 88 0.425 0.308 0.033 0.170 0.240 0.285 0.350 0.450 0.640 2.600

Murray River at Jingellic 89 0.260 0.122 0.013 0.130 0.160 0.190 0.220 0.330 0.390 0.940

Murray River at Union Bridge 86 0.361 0.111 0.012 0.140 0.250 0.280 0.350 0.430 0.520 0.710

Murray River d/s Yarrawonga Weir 88 0.384 0.210 0.022 0.190 0.230 0.280 0.320 0.450 0.550 1.900

Edward River at Deniliquin 87 0.389 0.155 0.017 0.200 0.250 0.290 0.340 0.450 0.570 0.980

Wakool River at Stoney Crossing 86 0.614 0.258 0.028 0.300 0.420 0.480 0.555 0.650 0.770 2.100

Wakool River at Kyalite 84 0.550 0.282 0.031 0.220 0.320 0.385 0.480 0.615 0.780 2.000

Murray River at Barham 82 0.447 0.277 0.031 0.140 0.250 0.280 0.325 0.510 0.820 1.600

Murray River u/s Euston Weir 83 0.662 0.385 0.042 0.170 0.320 0.390 0.550 0.790 1.300 1.800

Murray River at Merbein Pump Station 77 0.486 0.311 0.035 0.130 0.220 0.300 0.390 0.590 0.960 1.600

Darling River at Menindee Weir 32 76 1.232 0.427 0.049 0.530 0.690 0.930 1.200 1.500 1.800 3.000

Darling River at Burtundy 82 1.119 0.371 0.041 0.430 0.730 0.840 1.000 1.300 1.600 2.300

Murray River at Lock 8 23 0.462 0.156 0.032 0.280 0.290 0.350 0.420 0.540 0.640 0.880


















Turbidity (NTU)


Murray River at Indi Bridge 94 7.3 19 2.0 1.0 3.0 3.0 4.0 7.0 10 188

Tooma River at Warbrook 94 27 105 11 2.0 6.0 9.0 12 17 24 1000

Murray River at Jingellic 95 13 34 3.4 3.0 4.0 5.0 7.0 11 16 329

Murray River at Union Bridge 93 9.1 4.5 0.5 3.0 5.0 6.0 8.0 10 14 31

Murray River d/s Yarrawonga Weir 89 16 8.5 0.9 5.0 9.0 10 14 19 29 57

Edward River at Deniliquin 94 32 11 1.2 13 20 25 30 37 44 85

Wakool River at Stoney Crossing 89 41 24 2.5 7.0 9.0 20 39 56 68 127

Wakool River at Kyalite 94 52 25 2.6 6.0 29 36 50 64 77 164

Murray River at Barham 95 33 19 2.0 5.0 14 19 28 41 57 104

Murray River u/s Euston Weir 90 33 19 2.0 7.0 13 19 27 45 57 110

Murray River at Merbein Pump Station 80 31 31 3.5 0.8 10 14 23 37 63 250

Darling River at Menindee Weir 32 87 199 160 17 12 36 97 165 264 405 895

Darling River at Burtundy 93 208 198 20 9.0 19 86 148 287 451 1198

Murray River at Lock 8 24 36 20 4.2 14 14 17 30 53 69 74

Total Suspended Solids (mg/L)


Murray River at Indi Bridge 92 10 19 1.9 5.0 5.0 5.0 6.0 10 14 170



Tooma River at Warbrook 92 25 61 6.4 5.0 5.0 8.0 14 24 31 570

Murray River at Jingellic 93 12 18 1.9 5.0 5.0 5.5 9.0 13 20 170

Murray River at Union Bridge 90 8.9 4.8 0.5 5.0 5.0 5.0 7.4 11 14 27

Murray River d/s Yarrawonga Weir 88 14 7.1 0.8 5.0 6.5 10 14 17 23 56


Wakool River at Stoney Crossing 91 24 15 1.5 7.5 10 13 20 28 39 81


Murray River at Barham 88 35 25 2.7 7.0 14 20 30 40 59 180


Murray River at Merbein Pump Station 40 21 16 2.5 7.0 9 11 16 25 42 80

Darling River at Menindee Weir 32 4 20 7.9 4.0 12 12 14 18 26 30 30

Darling River at Burtundy 44 69 84 13 10 18 25 43 76 120 410

Murray River at Lock 8 23 17 6.5 1.4 6.0 11 12 17 19 26 36

Dissolved Oxygen (% saturation)


Murray River at Indi Bridge 92 97 3.8 0.4 84 91 95 97 99 101 106

Tooma River at Warbrook 94 90 5.4 0.6 74 81 86 90 94 96 99

Murray River at Jingellic 91 91 4.7 0.5 72 85 89 91 95 97 101

Murray River at Union Bridge 92 89 11 1.2 50 74 83 93 96 100 106

Murray River d/s Yarrawonga Weir 88 101 7.8 0.8 76 91 97 101 106 111 120


Wakool River at Stoney Crossing 87 90 17 1.8 23 77 84 92 98 104 122


Murray River at Barham 95 94 15 1.5 23 86 94 98 101 103 110


Murray River at Merbein Pump Station 86 99 16 1.7 18 91 96 101 106 112 131

Darling River at Menindee Weir 32 92 86 18 1.9 50 62 75 86 96 108 163

Darling River at Burtundy 93 90 21 2.1 47 69 79 91 96 110 191



Murray River at Lock 8 24 106 5 1.0 98 100 104 105 110 111 116

pH
















Electrical Conductivity (µS/cm)


Murray River at Indi Bridge 89 43 9.3 1.0 20 30 39 43 49 55 61

Tooma River at Warbrook 89 66 11 1.2 31 53 61 66 71 79 98

Murray River at Jingellic 90 40 7.6 0.8 26 30 35 40 46 51 58

Murray River at Union Bridge 89 50 7.7 0.8 34 41 45 52 57 61 67

Murray River d/s Yarrawonga Weir 89 56 6.9 0.7 38 46 51 56 62 64 72


Wakool River at Stoney Crossing 87 805 1311 141 67 98 138 203 660 2990 5330

Wakool River at Kyalite 84 160 144 16 55 85 98 130 166 202 1070



Murray River at Barham 83 78 18 1.9 52 60 65 77 87 96 149

Murray River u/s Euston Weir 94 120 39 4.0 75 83 92 109 134 178 314

Murray River at Merbein Pump Station 90 150 43 4.5 76 103 122 141 168 211 295

Darling River at Menindee Weir 32 89 538 402 43 116 242 318 417 512 1200 2057

Darling River at Burtundy 95 512 290 30 168 255 327 417 574 884 1780

Murray River at Lock 8 23 166 54 11 94 112 135 158 187 227 309



Table 28: Electrical conductivity in the Darling River at Burtundy and Murray River at Lock 6 for purposes of long term salinity planning

Year

Darling River at Burtundy

Salinity (EC µS/cm) Salt Load (t/year)

Murray River at Lock 6


Median

(50%ile)

Peak (80%ile) Total Median (50%ile) Peak (80%ile) Total

2008-2009 401 564 67228 249 292 178297

2009-2010 394 406 323 199 229 198061

2010-2011 325 359 557195 211 266 2116801

2011-2012 335 390 549513 194 253 1238268

2012-2013 483 530 401276 303 360 847017

2013-2014 520 577 75310 223 289 436997

2014-2015 846 916 11797 182 197 319856

2015-2016 1293 1627 321 170 197 241029

2016-2017 517 921 143829 222 285 1101578

Mean 200755 741989

Table 29: Electrical conductivity in Edward and Wakool Rivers for purposes of long term salinity planning

Edward River at Leiwah Wakool River at Stoney Crossing

Year Salinity (EC µS/cm) Salt Load (t/year)


Median

(50%ile)

Peak (80%ile) Total Median (50%ile) Peak (80%ile) Total

2001-2002 89 183 27796 503 680 44343

2002-2003 65 85 19619 335 515 34750

2003-2004 79 98 26331 328 443 37282

2004-2005 67 81 21452 280 333 32444

2005-2006 69 88 33943 233 437 33551

2006-2007 64 87 19219 380 517 25503

2007-2008 89 122 9446 1682 4102 13582

2008-2009 65 78 9853 3461 5042 26224

2009-2010 64 76 14971 776 1482 20235

2010-2011 120 157 133869 133 369 216204

2011-2012 142 177 98994 170 268 60557

2012-2013 126 152 54892 169 281 56631

2013-2014 107 136 40236 153 222 25525

2014-2015 83 99 33406 135 185 20436

Mean 38859 46233

NSW Department of Industry | PUBXX/YYYY | 76


Table 30: Electrical conductivity in the mid Murray River for purposes of long term salinity planning

Year



Murray River at Euston


Median (50%ile) Peak (80%ile) Total Median (50%ile) Peak (80%ile) Total

2001-2002 82 121 87210 199 265 238168

2002-2003 63 95 78053 114 165 171529

2003-2004 78 88 126799 115 135 202836

2004-2005 78 90 112267 115 130 189509

2005-2006 75 92 123916 111 126 218957

2006-2007 65 76 67549 96 124 119219

2007-2008 71 81 68160 95 132 94665

2008-2009 58 65 50091 79 116 89567

2009-2010 59 68 57377 88 104 98480

2010-2011 104 137 454724 156 187 1124117

2011-2012 98 127 300864 130 152 621889

2012-2013 87 97 210862 119 134 429305

2013-2014 81 95 151461 97 128 240270

2014-2015 82 90 157099 88 110 220858

Mean 146174 289955



Appendix E. Draftsman plots and Box plots by site The mean daily discharge, turbidity, total nitrogen, total phosphorus and total suspended solids data in the draftsman plots has been natural log transformed to normalise the distribution of the data. Some outlying data points have been removed from the data sets to maintain focus on the core data.

The box plots show the annual 25th, 50th and 75th percentile values, with error bars indicating the maximum and minimum values for each parameter. The data set extends from 2007 to 2015, and displays within site variability. In each figure there are numerous plots with A) total nitrogen, B) total phosphorus, C) turbidity, D) total suspended solids, E) dissolved oxygen, F) pH, G) electrical conductivity measured during monthly sampling and H) continuous electrical conductivity (where measured). Red lines indicate the Basin Plan water quality targets (and target ranges) from Schedule 11 of the Basin Plan for the appropriate zone. Total suspended solids have a lower detection limit of 5 mg/L.

Monitoring at the Murray River at Lock 8 commenced in July 2013, in response to the identification of a water quality data gap in the Lower Murray zone. There is insufficient data to show meaningful correlations in the draftsman plots and boxplots.



Murray River at Indi Bridge There was a positive correlation between total nitrogen and total phosphorus, indicating that both nutrients are transported via similar mechanisms. Nutrients were correlated to turbidity, but not to flow. Electrical conductvity had a slight negative correlation to flow.

The majority of total nitrogen and total phosphorus results were less than the respective Basin Plan targets, even during years of high flow. The annual median turbidity exceeded the target every year from 2009 to 2015. Dissolved oxygen and pH are both within the desired range. The electrical conductivity is very low with and annual median less than 50 µS/cm. Following the flooding in 2010, there was a slight increase in electrical conductivity from 2011 to 2014, and then decreasd again in 2014-2015. The increase is likely in response to the wetting up of the catchment in 2010, resulting in increased baseflow contributions from slightly more saline groundwater.

5.0 6.0 7.0 8.0

5.0

6.5

8.0

LnQ

85

95

10

5

DO

20

40

60

EC

0.0

50

.20

LnTN

6.4

6.8

7.2

pH

0.0

10

.03

LnTP

1.8

2.2

2.6

3.0

LnTSS

1.0

2.0

LnNTU

5.0 6.0 7.0 8.0

51

52

5

85 90 95 100 20 30 40 50 600.05 0.15 0.25 6.4 6.8 7.2 0.01 0.02 0.03 0.04 1.8 2.2 2.6 3.0 1.0 1.5 2.0 2.5 5 10 15 20 25

51

52

5

TEMP

Murray River at Indi Bridge

Figure 25: Draftsman plots for Murray River at Indi Bridge



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.0

0.1

0.2

0.3

0.4T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.01

0.02

0.03

0.04

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

5

10

15

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

5

10

15

20

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

80

90

100

110

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

6.5

7.0

7.5

8.0

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

25

50

75

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G)

Figure 26: Water quality data for Murray River at Indi Bridge



Tooma River at Warbrook The draftsman plots show a positive correlation between total nitrogen, total phosphorus and turbidity, with only total nitrogen and turbidity showing a positive correlation with flow. There was no correlation between electrical conductivity and flow.

The annual median turbidity and total phosphorus exceed the Basin Plan target every year, with total nitrogen exceeding the target in the high flow years from 2010-2012 and in 2013-2014. Total phosphorus results did not fluctuate in response to high flow years which is consistent with the draftsman plots for this site. The annual median dissolved oxygen was stable throughout the sampling period, with most results between 85 and 95% saturation. Some dissolved oxygen results during low flows dropped below the Basin Plan lower limit. The pH was mostly within the Basin Plan upper and lower limits. Electrical conductivity was low and generally stable, with the annual median fluctuating between 50 and 75 µS/cm. There was a slight increase in electrical conductivity in 2012-2013, but results had returned to a more normal level by 2014-2015.

4 5 6 7 8

45

67

8

LnQ

75

85

95

DO

30

50

70

90

EC

0.2

0.4

0.6

LnTN

6.5

7.0

7.5

pH

0.0

20

.06

0.1

0

LnTP

2.0

3.0

4.0

LnTSS

1.0

2.0

3.0

4.0

LnNTU

4 5 6 7 8

51

52

5

75 80 85 90 95 30 50 70 90 0.2 0.4 0.6 6.5 7.0 7.5 0.02 0.06 0.10 2.0 2.5 3.0 3.5 4.01.0 2.0 3.0 4.0 5 10 15 20 25

51

52

5

TEMP

Tooma River at Warbrook

Figure 27: Draftsman plots for Tooma River at Warbrook



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.25

0.50

0.75

1.00T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.000

0.025

0.050

0.075

0.100

0.125

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

80

90

100

110

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

6.5

7.0

7.5

8.0

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

25

50

75

100

125

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G)

Figure 28: Water quality data for Tooma River at Warbrook



Murray River at Jingellic There were strong correlations between total nitrogen, total phosphorus and turbidity, indicating transport by similar mechanisms. All three parameters were corrleated to flow. Electrical conductivity did not show a clear correlation to flow.

Total nitrogen, total phosphorus and turbidity all increased during the higher flow years from 2010 to 2012. The annual median turbidity exceeded the Basin Plan target every year. Total phosphorus exceeded the target from 2010 to 2012 while total nitrogen did not exceede the target. The majority of the dissolved oxygen results remained above the lower limit of 85% saturation and pH varied from year to year within the upper and lower range. Electrical conductivity was generally less than 50 µS/cm with a very small increase following the flooding in 2010.

7.0 8.0 9.0

7.0

8.0

9.0

LnQ

75

85

95

DO

25

35

45

55

EC

0.2

0.4

LnTN

6.4

7.0

7.6

pH

0.0

20

.06

LnTP

2.0

3.0

LnTSS

1.5

2.5

3.5

LnNTU

7.0 8.0 9.0

51

02

0

75 85 95 25 35 45 55 0.2 0.3 0.4 0.5 6.4 6.8 7.2 7.6 0.02 0.04 0.06 0.08 2.0 2.5 3.0 3.5 1.5 2.5 3.5 5 10 15 20 25

51

02

0

TEMP

Murray River at Jingellic

Figure 29: Draftsman plots for Murray River at Jingellic



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.0

0.2

0.4

0.6T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.000

0.025

0.050

0.075

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

10

20

30

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

80

90

100

110

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

6.5

7.0

7.5

8.0

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

25

50

75

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

25

50

75

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 30: Water quality data for Murray River at Jingellic



Murray River at Albury (Union Bridge) The Murray River at Albury site is located approximately 26 km downstream of Hume Dam. The quality of the water at this site is impacted by the quality and quantity of the water in Hume Dam. When stratified, the bottom waters of large storages can become anoxic, resulting in the release of nutrients and metals from the reservoir sediments.

There were positive correlations between total nitrogen, total phosphorus and turbidity, indicating transport by similar mechanisms. Total nitrogen showed a slight positive correlation to flow, while total phosphorus and turbidity did not. Electrical conductivity was not correlated to flow, due to the stabilising influence of releases from Hume Dam. Some low dissolved oxygen results were recorded during high flows.

Total nitrogen, total phosphorus and turbidity annual medians were all highest during the high flow year of 2010-2011. The annual median total phosphorus and turbidity did not exceed the Basin Plan target. Total nitrogen exceded the target in 2010-2011. The annual median dissolved oxygen was above the lower limit all years except for 2010-2011. The flooding and inundation of high banks and floodplains in 2010 may have resulted in decreased dissolved oxygen. The pH fluctuated between the upper and lower limits, and would not post a threat to aquatic ecosystems. Despite the release of low salinity water from Hume Dam, there was some fluctuation in electrical conductivity between years. Similar to the unregulated catchments, electrical conductivity increased between 2010 and 2012 in response to flooding and the subsequent recharge of shallow groundwater. From 2012 to 2015, electrical conductivity decreased to lower levels.

7 8 9 10

78

91

0

LnQ

50

70

90

DO

35

45

55

65

EC

0.2

0.4

LnTN

6.0

7.0

8.0

pH

0.0

10

.04

LnTP

2.0

2.5

3.0

LnTSS

1.5

2.5

3.5

LnNTU

7 8 9 10

51

02

0

50 70 90 35 45 55 65 0.2 0.3 0.4 0.5 6.0 7.0 8.0 0.01 0.03 0.05 2.0 2.5 3.0 1.5 2.0 2.5 3.0 3.55 10 15 20 25

51

02

0

TEMP

Murray River at Albury

Figure 31: Draftsman plots for Murray River at Albury



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.1

0.2

0.3

0.4

0.5

0.6T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.02

0.04

0.06

0.08

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

5

10

15

20

25

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

5

10

15

20

25

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

40

60

80

100

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

6.5

7.0

7.5

8.0

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 32: Water quality data for Murray River at Albury



Murray River downstream Yarrawonga Weir There were strong correlations between total nitrogen, total phosphorus and turbidity, indicating transport by similar mechanisms. All three parameters were correlated to flow, suggesting nutrients were transported attached to soil particles during high flow events. There was not a correlation between flow and electrical conductivity. The release of low salinity water from Hume Dam and minimal saline inputs downstream keeps the electrical conductivity at this site low.

Total nitrogen, total phosphorus and turbidity annual medians were all highest during the high flow year of 2010-2011, with the annual medians exceeding the Basin Plan targets. Dissolved oxygen fluctuated between the upper and lower limits. The monitoring site is located approximately 250 metres downstream of Yarrawonga Weir. The release water from Yarrawonga Weir could result in low dissolved oxygen results downstream. As the annual median was above 100% saturation most years, suggests this is not the case. The annual median pH was within the target range all years except for 2012-2013. The electrical conductivity shows a similar trend to the Albury site which is located approximately 70 kms upstream. Electrical conductivity increased between 2010 and 2012 in response to flooding and the subsequent recharge of shallow groundwater. From 2012 to 2015, the return of dryer years saw electrical conductivity decrease to lower levels.

8 9 10 11

89

10

LnQ

80

10

01

20

DO

40

50

60

70

EC

0.2

0.4

0.6

LnTN

6.0

7.0

8.0

pH

0.0

20

.06

LnTP

2.0

2.5

3.0

LnTSS

2.0

3.0

4.0

LnNTU

8 9 10 11

10

20

80 90 100 120 40 50 60 70 0.2 0.3 0.4 0.5 0.6 6.0 7.0 8.0 0.02 0.04 0.06 0.08 2.0 2.5 3.0 2.0 2.5 3.0 3.5 4.0 10 15 20 25

10

20

TEMP

Murray River downstream Yarrawonga Weir

Figure 33: Draftsman plots for Murray River downstream Yarrawonga Weir



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.25

0.50

0.75

1.00

1.25T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.000

0.025

0.050

0.075

0.100

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

10

20

30

40

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

10

20

30

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

80

90

100

110

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

0155.5

6.0

6.5

7.0

7.5

8.0

8.5

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 34: Water quality data for Murray River downstream Yarrawonga Weir



Edward River at Deniliquin The Edward River at Deniliquin had zero flow for most of the 2007 to 2015 period resulting in poor correlations between water quality attributes and flow. Total nitrogen and total phosphorus were strongly correlated to each other, indicating similar transport mechanisms. Nutrients were not as strongly correlated to turbidity.

The highest nutrient results were in 2010-2011 when higher flows were returned to the Edward River. Turbidity was slightly higher, but not to the same degree as nutrients. Total nitrogen exceeded the Basin Plan target in 2010-2011. Total nitrogen exceeded the target from 2010 to 2014, while turbidity exceeded the target every year. The annual median dissolved oxygen was within the desired range every year except for 2010-2011. Flooding and wide spread inundation of the floodplain resulted in a hypoxic blackwater event in the Edward River. The annual median pH was within the upper and lower limits all years. Flows in the Edward River are highly regulated, receiving diversions from the Murray River. As the electrical conductivity does not fluctuate greatly from year to year, suggests there is little surface water groundwater interaction.

0 2 4 6 8 10

02

46

8

LnQ

40

80

DO

60

10

0

EC

0.2

0.4

0.6

LnTN

6.0

7.0 pH

0.0

50

.15

LnTP

2.5

3.5

4.5

LnTSS

3.0

4.0

LnNTU

0 2 4 6 8 10

10

20

40 60 80 100 60 80 100 0.2 0.4 0.6 6.0 6.5 7.0 7.5 0.05 0.10 0.15 2.5 3.0 3.5 4.0 4.5 3.0 3.5 4.0 4.5 10 15 20 25

10

20

TEMP

Edward River at Deniliquin

Figure 35: Draftsman plots for Edward River at Deniliquin



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.25

0.50

0.75

1.00T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.05

0.10

0.15

0.20

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

40

60

80

100

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

6.0

6.5

7.0

7.5

8.0

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

50

100

150

200

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

50

100

150

200

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 36: Water quality data for Edward River at Deniliquin



Wakool River at Stoney Crossing Total nitrogen and total phosphorus were strongly correlated to each other, indicating similar transport mechanisms. Nutrients were not as strongly correlated to turbidity. Similar to the Edward River at Deniliquin, the Wakool River had zero flow for most of the 2007 to 2010 period, resulting in poor correlations between some water quality attributes and flow. Electrical conductivity was strongly correlated to flow with very high results during periods of no or low flow, and low results when salts were diluted by regulated flows.

The highest nutrient results were in 2010-2011, when higher flows were returned to the Wakool River. Total nitrogen, total phosphorus and turbidity annual medians exceeded the Basin Plan targets most years. The annual median dissolved oxygen was within the desired range most years. Flooding and widespread inundation of the floodplain in 2010-2011 resulted in a hypoxic blackwater event in the Wakool River. The electrical conductivity boxplots highlight the very high results from 2007 to 2010 during low flow. This indicates surface water and groundwater connectivity at this site, with highly saline groundwater contributing to base flow. The arrival of regulated flows, with low electrical conductivity, diluted the salts.

0 2 4 6 8 10

04

8

LnQ

04

08

01

20

DO

02

00

05

00

0

EC

0.3

0.5

0.7

LnTN

6.5

7.5

pH

0.0

20

.06

0.1

0

LnTP

2.5

3.5

LnTSS

2.0

3.0

4.0

LnNTU

0 2 4 6 8 10

10

20

0 20 60 100 0 2000 4000 0.3 0.5 0.7 6.5 7.0 7.5 8.0 0.02 0.06 0.10 2.5 3.0 3.5 4.0 2.0 3.0 4.0 10 15 20 25

10

20

TEMP

Wakool River at Stoney Crossing

Figure 37: Draftsman plots for Wakool River at Stoney Crossing



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.0

0.5

1.0

1.5

2.0T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.05

0.10

0.15

0.20

0.25

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

100

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

100

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

0156.0

6.5

7.0

7.5

8.0

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

1000

2000

3000

4000

5000

6000

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

1000

2000

3000

4000

5000

6000

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 38: Water quality data for Wakool River at Stoney Crossing



Wakool River at Kyalite There is now flow data available for the Wakool at Kyalite monitoring site. The Kyalite site is located approximately 20 kms downstream of the Stoney Crossing site. The Edward River, which receives flows from Billabong Creek from the Murrumbidgee WRPA, joins the Wakool River between the two sites.

Total nitrogen and total phosphorus were strongly correlated to each other, indicating similar transport mechanisms. Nutrients were not as strongly correlated to turbidity.

The highest nutrient results were in 2010-2011, when higher flows were returned to the Wakool River. Total phosphorus and turbidity annual medians exceeded the Basin Plan targets most years. The annual median dissolved oxygen was close to or below the lower limit most years. Flooding and widespread inundation of the floodplain in 2010-2011 resulted in a hypoxic blackwater event in the Wakool River. The electrical conductivity boxplots highlight the very high results from 2007 to 2010 during low flow. This indicates surface water and groundwater connectivity at this site, with highly saline groundwater contributing to base flow. The pH fluctuated from year to year, but generally remained within the desired range.

0 20 40 60 80 100

04

08

0

DO

10

03

00

EC

0.2

0.4

0.6

0.8

LnTN

6.5

7.5

pH

0.0

40

.08

0.1

2

LnTP

2.5

3.5

4.5

LnTSS

2.0

3.0

4.0

5.0

LnNTU

0 20 40 60 80 100

10

20

30

100 200 300 400 0.2 0.4 0.6 0.8 6.5 7.0 7.5 8.0 0.04 0.08 0.12 2.5 3.0 3.5 4.0 4.5 2.0 3.0 4.0 5.0 10 15 20 25 30

10

20

30

TEMP

Wakool River at Kyalite

Figure 39: Draftsman plots for Wakool River at Kyalite



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.25

0.50

0.75

1.00

1.25

1.50T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.05

0.10

0.15

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

100

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

100

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

100

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

6.0

6.5

7.0

7.5

8.0

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

250

500

750

1000

1250

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G)

Figure 40: Water quality data for Wakool River at Kyalite



Murray River at Barham There were strong correlations between total nitrogen, total phosphorus and turbidity, indicating transport by similar mechanisms. All three parameters were correlated to flow, suggesting nutrients were transported attached to soil particles during high flow events. There was not a correlation between flow and electrical conductivity. The lowest dissolved results were during high flow events.

As for many sites, the highest nutrient results were in 2010-2011, when higher flows were returned to the Murray River. Turbidity annual medians exceeded the Basin Plan targets most years. The annual median dissolved oxygen was within the desired range all years except for 2010-2011. Flooding and widespread inundation of the floodplain in 2010-2011 resulted in a hypoxic blackwater event in the Murray River. The pH fluctuated from year to year, but generally remained within the desired range. The electrical conductivity was stable, due to the release of low salinity water from Hume Dam.

7.5 8.5 9.5

7.5

8.5

9.5

LnQ

20

60

10

0

DO

60

10

01

40

EC

0.0

0.4

0.8

LnTN

6.0

7.0

8.0

pH

0.0

20

.08

0.1

4

LnTP

2.0

3.5

5.0

LnTSS

2.0

3.0

4.0

LnNTU

7.5 8.5 9.5

10

20

20 40 60 80 100 60 80 120 0.0 0.4 0.8 6.0 7.0 8.0 0.02 0.06 0.10 0.142.0 3.0 4.0 5.0 2.0 3.0 4.0 10 15 20 25

10

20

TEMP


Figure 41: Draftsman plots for Murray River at Barham



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.25

0.50

0.75

1.00

1.25T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.05

0.10

0.15

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

25

50

75

100

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

25

50

75

100

125

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

100

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

6.0

6.5

7.0

7.5

8.0

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

50

100

150

200

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

50

100

150

200

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 42: Water quality data for Murray River at Barham



Murray River upstream Euston Weir Total suspended soilds was added to the monitoring program for Euston Weir in 2011.

There was a strong positive correlation between total nitrogen and total phosphorus indicating similar transport mecahisms. Total phosphorus was positively correlated to turbidity, while total nitrogen was not. Nutrients and turbidity were both correlated to flow.

Total nitrogen and total phosphorus concentrations were highest during the high flows in 2010-2011, but were less than the Basin Target most years. Turbidity readings increased in 2010-2011, and remained high until 2014-2015. Water quality samples at this site are collected on the upstream side of the weir from within the weir pool. There may be some settling of heavier particles in the upper reaches of the weir pool, leaving the finer clay particles in suspension. The annual median dissolved oxygen was within the desired range most years, except for 2010-2011. Flooding and widespread inundation of the floodplain in 2010-2011 resulted in a hypoxic blackwater event in the Murray River. The pH fluctuated from year to year, but generally remained within the desired range. The electrical conductivity increased in 2010-2011. Flooding may have flushed salts into the Murray River from smaller tributaries and from the soil surface. Recharge of the groundwater by flooding may have reconected the shallow saline aquifers with the river, increasing saline inputs. Electrical conductivity decreased in subsequent years due to the release of low salinity water from Hume Dam. Euston Weir is upstream of the salt interception schemes located in the Mildura area.

7.5 8.5 9.5 10.5

7.5

9.0

10

.5

LnQ

20

60

10

0

DO

10

02

00

30

0

EC

0.2

0.6

1.0

LnTN

6.5

7.5

pH

0.0

50

.15

LnTP

2.0

3.0

4.0

LnTSS

2.0

3.0

4.0

LnNTU

7.5 8.5 9.5 10.5

10

20

20 40 60 80 100 200 300 0.2 0.4 0.6 0.8 1.0 6.5 7.0 7.5 8.0 0.05 0.10 0.15 2.0 3.0 4.0 2.0 3.0 4.0 10 15 20 25

10

20

TEMP

Murray River upstream Euston Weir

Figure 43: Draftsman plots for Murray River upstream Euston Weir



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.0

0.5

1.0

1.5

2.0T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.05

0.10

0.15

0.20

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

100

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

100

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

100

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

0156.0

6.5

7.0

7.5

8.0

8.5

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

50

100

150

200

250

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

50

100

150

200

250

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 44: Water quality data for Murray River upstream Euston Weir



Murray River at Merbein Pump Station Total suspended soilds was added to the monitoring program for Merbein Pump Station 2011.

There was a strong positive correlation between total nitrogen and total phosphorus, indicating similar transport mecahisms. Nutrients had a stronger correlation to flow than to turbidity. Turbidity was not correlated to flow.

As for many sites, total nitrogen, total phosphorus concentrations and turbidity were highest during the high flows in 2010-2011, exceeding the Basin Plan target. Annual medians for these three atributes did not exceed the target values other years. The annual median dissolved oxygen was within the desired range most years, except for 2010-2011 during the hypoxic blackwater event in the Murray River. The pH fluctuated from year to year, but generally remained within the desired range. Electrical conductivity was low with minor fluctuations between years.

7.5 8.5 9.5 10.5

7.5

9.0

10

.5

LnQ

20

60

10

0

DO

10

02

00

30

0

EC

0.2

0.6

LnTN

6.5

7.5

8.5

pH

0.0

20

.08

LnTP

2.0

3.0

4.0

LnTSS

12

34

5

LnNTU

7.5 8.5 9.5 10.5

10

20

30

20 60 100 100 200 300 0.2 0.4 0.6 0.8 6.5 7.0 7.5 8.0 8.5 0.02 0.06 0.10 2.0 2.5 3.0 3.5 4.0 1 2 3 4 5 10 15 20 25 30

10

20

30

TEMP

Murray River at Merbein Pump Station

Figure 45: Draftsman plots for Murray River at Merbein Pump Station



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.0

0.5

1.0

1.5

2.0T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.05

0.10

0.15

0.20

0.25

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

50

100

150

200

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

20

40

60

80

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

20

40

60

80

100

120

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

6.0

6.5

7.0

7.5

8.0

8.5

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

50

100

150

200

250

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G)

Figure 46: Water quality data for Murray River at Merbein Pump Station



Darling River at Weir 32 Analysis of total suspended solids was added to the parameter list for this site in 2014.

There was a positive correlation between total phosphorus and turbidity, and a slight correlation between total nitrogen and total phosphorus. Dissolved oxygen and pH were positively correlated, suggesting algal growth in the weir pool could be increasing both parameters. The highest electrical conductivity results were measured during low and zero flows, when salts can become concentrated in the weir pool by evaporation. Electrical conductivity was also negatively correlated to turbidity.

The total nitrogen and total phosphorus concentrations did not fluctuate greatly from year to year in response to changes in flow, as occurred in monitoring sites on the Murray River. Weir 32 is located approximately 40 km downstream of Lake Wetherell. The process of flows from the upper Darling catchment, passing through Menindee Lakes, appears to have a smoothing effect on nutrient concentrations. Nutrient concentrations exceeded the Basin Plan targets every year. The annual median turbidity exceeded the target most years, except for 2007-2008 and 2014-2015 when electrical conductivity was high. High concentrations of salt can cause soil particles to settle out of the water column, resulting in lower turbidity. The alluvial soils of the Darling River have a high clay content which increases their susceptibility to resuspension within the water column. In addition, the very fine particles are able to remain in suspension, even during low or zero flow periods. The low dissolved oxygen results from 2010 to 2012 coincide with the highest turbidity results. High turbidity, reducing light penetration into the water column, inhibiting aquatic plant growth, could be causing the lower dissolved oxygen results.

0 2 4 6 8 10

02

46

8

LnQ

60

10

01

40

DO

50

01

50

0

EC

0.4

0.8

1.2

LnTN

6.5

7.5

8.5

pH

0.1

0.3

0.5

LnTP

34

56

LnNTU

0 2 4 6 8 10

10

20

60 80 120 160 500 1000 1500 20000.4 0.6 0.8 1.0 1.2 1.4 6.5 7.5 8.5 0.1 0.3 0.5 3 4 5 6 10 15 20 25

10

20

TEMP

Darling River upstream Weir 32

Figure 47: Draftsman plots for Darling River at Weir 32



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.0

0.5

1.0

1.5

2.0

2.5

3.0T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.00

0.25

0.50

0.75

1.00

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

200

400

600

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

200

400

600

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

40

60

80

100

120

140

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

0156.5

7.0

7.5

8.0

8.5

9.0

9.5

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

500

1000

1500

2000

2500

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

500

1000

1500

2000

2500

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 48: Water quality data for Darling River at Weir 32



Darling River at Burtundy Analysis of total suspended solids was added to the parameter list for this site in 2011.

There was a positive correlation between total phosphorus and turbidity, and between both parameters and flow. Total nitrogen does not appear to be correlated to total phosphorus, turbidity or flow. Dissolved oxygen and pH were positively correlated, suggesting algal growth in the weir pool could be increasing both parameters. The highest electrical conductivity results were measured during low and zero flows, when salts can become concentrated by evaporation. Electrical conductivity was also negatively correlated to turbidity.

There were similar water quality trends visible at the Burtundy site, as at Weir 32. Nutrient concentrations exceeded the Basin Plan targets every year. The annual median turbidity exceeded the target most years, except for 2007-2008 and 2014-2015 when electrical conductivity was high. The low dissolved oxygen results from 2010 to 2012 coincide with the highest turbidity results. Electrical conductivity results increased between 2010 and 2015.

0 2 4 6 8 10

04

8

LnQ

50

10

0 DO

50

01

50

0

EC

0.4

0.8

1.2

LnTN

7.0

8.0

9.0

pH

0.0

0.2

0.4

LnTP

34

56

LnTSS

34

56

7

LnNTU

0 2 4 6 8 10

10

20

30

50 100 150 500 1000 1500 0.4 0.6 0.8 1.0 1.2 7.0 8.0 9.0 0.0 0.1 0.2 0.3 0.4 3 4 5 6 3 4 5 6 7 10 15 20 25 30

10

20

30

TEMP

Darling River at Burtundy

Figure 49: Draftsman plots for Darling River at Burtundy



2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.0

0.5

1.0

1.5

2.0

2.5T

N (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0.0

0.1

0.2

0.3

0.4

0.5

TP

(m

g/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

100

200

300

400

500

600

700

Turb

idity (

NT

U)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

100

200

300

400

500

TS

S (

mg/L

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

40

60

80

100

120

140

160

DO

(%

sat)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

0156.5

7.0

7.5

8.0

8.5

9.0

9.5

pH

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

250

500

750

1000

1250

1500

EC

(µS

/cm

)

2007/2

008

2008/2

009

2009/2

010

2010/2

011

2011/2

012

2012/2

013

2013/2

014

2014/2

015

0

200

400

600

800

1000

EC

(µS

/cm

)

A) B)

C) D)

E) F)

G) H)

Figure 50: Water quality data for Darling River at Burtundy


Documents

Water quality technical report for Murray Lower …...lowlands Water quality technical report for Murray Lower Darling surface water resource plan area (SW8) Summary Good quality water