PROJECT SEA DRAGON STAGE 1 LEGUNE GROW … · Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality i Summary ... approximately 330 km

Volume 5 - Appendices Appendix 12 - Freshwater Water Quality and Ecology 1

VOLUME 5 - APPENDICES

APPENDIX 12 - FRESHWATER WATER QUALITY AND ECOLOGY

PROJECT SEA DRAGON

STAGE 1 LEGUNE GROW-OUT FACILITY

DRAFT ENVIRONMENTAL IMPACT STATEMENT

Project Sea Dragon

Stage 1 Grow- Out Facility

Environmental Impact

Statement

Freshwater Ecology and Water

Quality

Prepared for:

CO2 Australia Limited

frc environmental

PO Box 2363, Wellington Point QLD 4160 Telephone: + 61 3286 3850

Facsimile: + 61 3821 7936

frc reference: 150911 freshwater

frc environmental

This w ork is copyright.

A person using frc environmental documents or data accepts the risk of:

1 Using the documents or data in electronic form w ithout requesting and checking them for accuracy against the

original signed hard copy version; and

2 Using the documents or data for any purpose not agreed to in w riting by frc environmental.

Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality

Projects:2015:150911_CO2_PSD_October:Report:EIS:Current:Legune:150911Rii_Legune_16-09-12_1303_TP.docx

Document Control Summary

Project No.: 150911 freshwater

Status: Final Report

Project Director: Carol Conacher

Project Manager: Craig Chargulaf

Title: Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and

Water Quality

Project Team: Christoph Braun, Craig Chargulaf, Carol Conacher, Benjamin Cook, Cameron Forward,

John Thorogood, Liz West

Client: CO2 Australia Limited

Client Contact: Kate McBean and Natasha McIntosh

Date: 12 September 2016

Edition: 150911Rii

Checked by: Carol Conacher

Issued by: Liz West

Distribution Record

CO2 Australia Limited: 1 pdf

frc environmental


Contents

Summary i

1 Introduction 1

1.1 Project Background 1

1.2 Scope and Objectives of the Study 1

1.3 Overview of the Area Surrounding the Proposed Development 2

1.4 Existing Disturbances 4

2 Methods 7

2.1 Literature Review 7

2.2 Field Surveys 7

2.3 Water Quality Surveys 11

2.4 Sediment Quality 14

2.5 Macroinvertebrate Communities 15

2.6 Fish 17

2.7 Reptiles 18

2.8 Limitations and Constraints 18

3 Legislation 19

3.1 Environmental Protection and Biodiversity Conservation Act 1999 19

3.2 Environmental Offsets Policy 2012 21

3.3 Northern Territory’s Territory Parks and Wildlife Conservation Act 21

3.4 Northern Territory’s Fisheries Act 23

3.5 Northern Territory’s Water Act 23

3.6 Northern Territory’s Environmental Assessment Act 24

4 Overview 25

5 Water Quality 33

5.1 Water Quality of Water Bodies on Legune Station 34

frc environmental


6 Sediment Quality 50

6.1 Sediment Composition and Quality of Water Bodies on Legune

Station 51

7 Aquatic Flora and Fauna 59

7.1 Aquatic flora 59

7.2 Macroinvertebrate Communities 62

7.3 Fish 69

7.4 Aquatic Reptiles 79

8 Conceptual Model 81

9 Potential Impacts and Mitigation 83

9.1 Direct Impacts 85

9.2 Alteration of Local Hydrology 86

9.3 Reducing Cattle Grazing 87

9.4 Waterway Barriers 87

9.5 Vegetation Clearing and Earthworks 88

9.6 Release of Wastewater 90

9.7 Spills of Hydrocarbons and Other Contaminants 91

9.8 Proliferation of Pest Species 92

9.9 Waste and Litter 93

9.10 Increased Site Access 94

9.11 Cumulative Impacts 94

9.12 Climate Change 94

9.13 Risk Assessment 96

10 Environmental Management and Monitoring 99

10.1 Water Quality 99

10.2 Environmental Management Plan 100

11 References 104

frc environmental


12 Additional Information 110

12.1 People Involved in Preparing this Document 110

Tables

Table 2.1 Water quality and aquatic ecological sampling program. 10

Table 2.2 Summary of water quality assessments. 12

Table 3.1 Likelihood of fish and turtle listed as threatened under the TPWC

occurring near the proposed development. 22

Table 4.1 Aquatic habitat at each site 27

Table 5.1 The physical and chemical stressors at each site compared to

the relevant AWQG. 41

Table 5.2 The maximum concentration of ammonia and nitrate (mg/L) in

the water at each site, and the AWQG trigger values for these

parameters as toxicantsa. 44

Table 5.3 The maximum concentration of total metals and metalloids

(mg/L) in the water at each site, and the AWQG trigger valuesa. 44

Table 5.4 The maximum concentration of dissolved metals and metalloids

(mg/L) in the water at each site, and the AWQG trigger valuesa. 45

Table 5.5 The maximum concentration of organochlorine pesticides (µg/L)

in the water at each sitea. 46

Table 5.6 The maximum concentration of organophosphorous pesticides

(µg/L) in the water at each sitea. 47

Table 5.7 The maximum concentration (µg/L) of recoverable hydrocarbons

in the water at each sitea. 48

Table 5.8 The concentration of BTEXN (µg/L) in the watera. 48

Table 5.9 Phytoplankton communities (cells/mL) at each site in March

2016. 49

Table 6.1 Sediment quality at each site in June and October 2015

compared to the sediment quality guidelines. 53

frc environmental


Table 6.2 Sediment quality at each site in March 2016 compared to the

sediment quality guidelines. 56

Table 7.1 Aquatic plant species of the Victoria River catchment a. 59

Table 7.2 Fish species recorded in the Keep, Ord and Victoria Rivers. 72

Table 7.3 Fish species caught on Legune Station in the 2015 dry and 2016

wet season surveys. 78

Table 9.1 Risk assessment matrix. 96

Table 9.2 Summary of potential impacts on freshwater ecosystems. 97

Table 10.1 Proposed water quality and aquatic plants and macroinvertebrate

sites. 99

Table 12.1 frc environmental staff who prepared this report and / or

completed field surveys. 110

Figures

Figure 4.1 Turkey’s nest dam and surrounding wetland area in the wet

season (January 2016). 26

Figure 4.2 Forsyth Creek Dam on the southern end of Legune station in the

post-wet season (March 2016). 26

Figure 4.3 Skeleton of dead fish likely to have been stranded in the dry

season. 26

Figure 5.1 Percent saturation of dissolved oxygen at each site in each

survey. 36

Figure 5.2 Turbidity at each site in each survey. 37

Figure 5.3 Electrical conductivity at each site in each survey. 37

Figure 5.4 Concentration of total nitrogen at each site in each survey. 38

Figure 5.5 Concentration of oxides of nitrogen at each site in each survey. 38

Figure 5.6 Concentration of ammonia at each site in each survey. 39

frc environmental


Figure 5.7 Concentration of total phosphorus at each site in each survey. 39

Figure 5.8 Concentration of chlorophyll a at each site in each survey. 40

Figure 7.1 Water snowflake. 61

Figure 7.2 Clubrush. 61

Figure 7.3 Azolla. 61

Figure 7.4 Pond weed. 62

Figure 7.5 Non-metric multi-dimensional scaling plot of freshwater

macroinvertebrate communities at each site in each survey. 64

Figure 7.6 Mean abundance of freshwater macroinvertebrates at each site

in each survey. 65

Figure 7.7 Mean taxonomic richness of freshwater macroinvertebrates at

each site in each survey. 66

Figure 7.8 Mean PET richness of freshwater macroinvertebrates at each

site in each survey. 67

Figure 7.9 Mean SIGNAL 2 scores at each site in each survey. 68

Figure 7.10 Smalleye gudgeon (Prionobutis microps) caught in Forsyth Creek

in March 2016. 77

Figure 7.11 Glassfish (Ambassis spp.) were common in both surveys. 77

Figure 7.12 Oxeye herring (Megalops cyprinoides) in Alligator Creek in

October 2015. 77

Figure 8.1 Conceptual model of transport of nutrients and ecological

processes in water bodies on Legune Station. 82

Maps

Map 1.1 Major catchments surrounding the project area. 6

Map 2.1 Sites surveyed. 9

frc environmental

Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality i

Summary

Project Sea Dragon is a large scale, greenfield land based aquaculture project in northern

Australia. It will be delivered as an integrated production system, providing reliable, long-

term, high quality and large-scale production of black tiger prawns (Penaeus monodon). It

focuses on sustainable land use and integrated design practices to maintain surrounding

river and coastal environments and support adjacent agricultural land uses.

The proposed grow-out facility for Project Sea Dragon will be on Legune Station, on the

bight of the Joseph Bonaparte Gulf, in the north-west of the Northern Territory,

approximately 330 km south-west of Darwin. This report was prepared to support the

Environmental Impact Statement (EIS) for the construction and operation of Stage 1 of the

Grow-out Facility (the Project) with respect to the water quality and ecology of the aquatic

ecosystems on the site.

This report presents the findings of field and desktop investigations of the freshwater

water bodies on Legune Station, on behalf of CO2 Pty Ltd, and addresses issues relating

to aquatic ecology and freshwater quality outlined in the Northern Territory (NT)

Environmental Protection Authority (EPA) Terms of Reference (ToR) for the Preparation

of an Environmental Impact Statement (EIS) – Project Sea Dragon Stage 1 Legune Grow-

out Facility.

The area was first surveyed in the dry season in June 2015. Results from this survey

were used to inform baseline monitoring programs for freshwater quality and aquatic

ecology. Following the initial scoping survey in the dry season, there were another two

detailed assessments of water quality and aquatic ecology, and two less detailed

assessments of water quality.

Overview

The project area is remote with no major industrial development in the region and the

nearest population centre approximately 106 km to the south-west. The project site is a

pastoral lease, which is currently primarily used for cattle grazing. Native vegetation has

previously been cleared and levee banks and operational dams have been installed in a

number of locations to maintain the improved pasture species sown into the fenced

paddocks network. There are currently approximately 30 000 cattle on the station.

Aquatic habitat around Legune Station comprises a variety of waterways and associated

vegetation including freshwater creeks, spring-fed waterholes, tidally inundated creeks,

ephemeral wetlands and man-made dams. The ephemeral wetlands are predominantly

created by overland flows, and dry out in the dry season. Prior to the wet season each

frc environmental

Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality ii

year (usually in August), water is released from the Forsyth Creek Dam. This creates flow

and increases water levels across much of the site in the late dry season, with most of the

water pooling in the upper, non-tidal reaches of Alligator Creek.

Water Quality

Freshwater water bodies in the region are characteristically ephemeral, filling in the wet

season and drying out in the dry season. While there are extensive floodplains in the wet

season, in the dry season surface water is confined to small channels, billabongs and

swamps. These water bodies gradually evaporate, becoming stagnant and commonly

drying out. Storms in the early wet season result in turbid ‘flushes’ from surface run-off

from the catchment, from stagnant pools in the riverbed, and from previously dried up

water bodies. These flushes are characterised by high concentrations of decayed organic

matter, and low oxygen content, and can result in a rapid deterioration of water quality.

Water quality in the creeks on Legune Station was relatively poor and characterised by

low dissolved oxygen, high turbidity and high nutrients in the dry and pre-wet seasons. In

Forsyth Creek Dam water quality was poorest in the pre-wet season, with low dissolved

oxygen and higher nutrients at this time. Water quality in the ephemeral wetlands was

poor to moderate, and characterised by low dissolved oxygen and high turbidity,

particularly in the remaining water in the dry season.

The concentration of potential toxicants was low in water bodies on the station, although

there were elevated concentrations of metals and metalloids at some sites.

Sediment Quality

Sediment in the waterbodies on site was predominantly fine, including silt / clay with some

sand. Fine sediments are more susceptible to resuspension and transportation

downstream than coarser sediments, and are more likely to accumulate contaminants

through adsorption. The concentration of most metals and metalloids were below the

sediment quality guideline values. Lead was above the high trigger value at one site in

June 2015. The concentration of all other potential contaminants was low, either below

sediment quality trigger levels, or below the laboratory limit of reporting.

Aquatic Flora

Thirteen species of aquatic plants were recorded along the waterways of Legune Station.

Water lilies were the most common species recorded. No listed species or declared pest

aquatic plant species were recorded in the surveys. All species are commonly occurring

frc environmental

Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality iii

aquatic plants, many of which are typical of disturbed ecosystems (e.g. cumbungi and

azolla).

Macroinvertebrate Communities

Freshwater macroinvertebrate communities were dominated by taxa common to

moderately disturbed ecosystems. Freshwater macroinvertebrate communities were

significantly different between March 2016, and June 2015 and October 2015, mostly due

to higher abundances of water boatmen (family Corixidae) and non-biting midge larvae

(sub-family Chironominae) in June and October 2015. These two species are commonly

found in slow moving or still waters and are a good food source for fish. Communities

were more likely influenced by habitat and flows, with higher flows and more area

inundated in the March 2016 survey, following the wet season.

Fish

Eleven fish species were caught or observed in the waterbodies on Legune Station, while

approximately 90 species have been previously been recorded in the Keep, Victoria and

Ord River catchments. Many of these species are ‘marine vagrants’ that irregularly use

freshwater reaches of the rivers.

Most species recorded in these rivers systems may periodically occur on Legune Station.

However, the characteristic lack of dense vegetation and high turbidity of the water bodies

on the station limits the distribution of some of these species.

Movement and migration are key components of the biology and ecology of northern fish

as species move to access food sources, for reproduction and to access refugial habitats

depending on the season. Barriers to movement, such as the existing roads and bunds

on the station, can limit the distribution and reproduction of fish.

Waterbodies such as Forsyth Dam and Osman’s Lagoon are likely to provide refugial

habitat in the dry season for a variety of species.

Of the species recorded in the region, the Angalarri grunter (Scortum neili) is classified as

vulnerable and Obbes catfish (Porochilus obbesi) is classified as near threatened under

the Northern Territory TPWC Act. Several sawfish and river shark species may also occur

in freshwater reaches of the Project area; however, they are discussed in Project Sea

Dragon Stage 1: Environmental Impact Statement Estuarine Receiving Environment

report (frc environmental 2016).

frc environmental

Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality iv

Aquatic Reptiles

Salt-water and freshwater crocodiles were observed in the freshwater bodies around

Legune Station in each survey.

Four species of freshwater turtle species are recorded in the region; however, no turtles

were caught in the current surveys. There was potential habitat around Legune Station

for the northern-long-necked turtle (Chelodina rugosa), and potentially the northern red-

faced turtle (Emydura victoriae) and northern snapping turtle (Elseya dentata).

Potential Impacts

Potential impacts of Stage 1 of Project Sea Dragon to the freshwater aquatic ecosystems

on Legune Station include:

removal of habitat under the Project footprint

changes to hydrology from the construction of infrastructure and the cessation of

pre-wet season discharge from Forsyth Creek Dam, returning it to pre dam

condition

changes to water quality resulting from the cessation of the pre-wet season

discharge, returning it to pre dam condition

waterway barriers

increased erosion and runoff from vegetation clearing and earthworks

changes in water quality from wastewater irrigation systems

spills of hydrocarbons or other contaminants

proliferation of pest species

litter and waste, and

increased site access

The risk of significant impacts to freshwater aquatic ecosystems on Legune Station can be

significantly reduced where a variety of mitigating measures are used. Nevertheless there

may be some residual impacts comprised of wet season habitat loss directly under the

footprint.

frc environmental

Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality v

Environmental Monitoring and Management

Environmental monitoring is required throughout the life of the project to determine the

effectiveness of the mitigation measures put in place. The monitoring program is

designed to be able to detect any change in a statistically robust manner should

operational or construction activities affect water quality or aquatic ecology (using

macroinvertebrates as an indicator).

Environmental risks to the aquatic ecology of the waterbodies on Legune Station should

be managed under the environmental management plan, which incorporates an

appropriate:

Wastewater and Stormwater Management Plan

Erosion and Sediment Management Plan

Acid Sulfate Soil Management Plan (where appropriate)

Pest Management Plan

Waste Minimisation and Management Plan, and

Spill Management Plan.

frc environmental

Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality 1

1 Introduction

1.1 Project Background

Project Sea Dragon is a large scale, greenfield land based aquaculture project in northern

Australia. It will be delivered as an integrated production system, providing reliable, long-

term, high quality and large-scale production of Black Tiger prawns (Penaeus monodon).

It focuses on sustainable land use and integrated design practices to maintain

surrounding river and coastal environments and support adjacent agricultural land uses.

The proposed Grow-out Facility for Project Sea Dragon will be on Legune Station, on the

bight of the Joseph Bonaparte Gulf. It is approximately 330 km southwest of Darwin, in the

north-west of the Northern Territory. This report was prepared to support the

Environmental Impact Statement (EIS) for the construction and operation of Stage 1 of the

Grow-out Facility (the Project) with respect to the water quality and aquatic ecology of the

freshwater bodies on the site.

The Stage 1 Grow-out Facility will comprise approximately 1 080 ha of prawn farming

capacity, plus associated infrastructure on-site. Water will be extracted from Forsyth

Creek for use in the grow-out ponds. Water will be discharged via an environmental

protection zone (EPZ) into Alligator Creek.

1.2 Scope and Objectives of the Study

This report presents the findings of field and desktop investigations of the aquatic ecology

and water quality of the fresh water bodies on Legune Station. It addresses issues

relating to aquatic ecology and water quality outlined in the Northern Territory (NT)

Environmental Protection Authority (EPA) Terms of Reference (ToR) for the Preparation

of an Environmental Impact Statement (EIS) – Project Sea Dragon Stage 1 Legune Grow-

out Facility.

The potential and likely impacts of the Project on the receiving water and to aquatic

species and communities were also assessed, and opportunities for impact mitigation are

discussed.

frc environmental


1.3 Overview of the Area Surrounding the Proposed Development

The regional climate of the project area is tropical monsoonal, with a hot and dry season

from approximately June to August and a hot and humid wet season from approximately

December to March. The timing and intensity of the wet season varies each year, and

there are transitional conditions between these two periods that vary in length. The dry

season is influenced by easterly winds generated over inland Australia, resulting in dry

and warm conditions, with very little rainfall and low relative humidity. The wet season is

influenced by high humidity and thunderstorm activity caused by steady west to northwest

winds, bringing moisture from the Timor Sea. Rainfall in the region is highest in the late

wet season. The tropical cyclone season between November and April overlaps the wet

season. Local rainfall across the Project area is highly variable and usually influenced by

brief intense storms (Water Technology 2016a).

The Project area is at the end of two major catchments, the Victoria River and the Keep

River catchments, which drain into the Joseph Bonaparte Gulf and ultimately to the Timor

Sea (Map 1.1).

The Victoria River catchment (87 900 km2) includes the Victoria River and its major

tributaries. The flow regime of this catchment is classed as a combination of ‘predictable

summer highly intermittent’ and ‘variable summer extremely intermittent’ (Ward et al.

2011), with high flows associated with a summer wet season. The Victoria River

originates on Riveren Station and runs approximately 720 kilometres through a mixture of

grassy plains, rolling savannahs, rocky Spinifex country, mesas and plateaus before

draining into the Joseph Bonaparte Gulf to the northeast of Legune Station. Most of the

catchment is less than 450 metres above sea level.

The Keep River catchment (6 003 km2) includes the Keep River and its major tributaries,

including Border Creek, draining the western fringes and Sandy Creek, draining the

eastern fringes of the Keep River plain. Sandy Creek originates just south of Newry

Station and flows approximately 260 km north, crossing the Victoria Highway, through the

Keep River National Park, veering westward across the border into Western Australia and

back into the Northern Territory to the east of Legune Station. To the south east of Sandy

Creek there is a large seasonal water body, Osman’s Lake. This is a naturally occurring

lake that fills with surface water in the wet season, and dries out in the dry season.

Osman’s Lake and its associated catchment are unlikely to be affected by the Project

(Water Technology 2016a).

Alligator Creek is on the western side of Legune Station, and its catchment runs north

west across the floodplain on the western (Keep River) side of the station. Forsyth Creek,

to the east of the project footprint, has its catchment in the south of the property and runs

north across the floodplain on the eastern (Victoria River) side. The floodplain

frc environmental


hydrological conditions of both the Forsyth Creek and Alligator Creek catchments have

been substantially modified over time by the instatement of various bunds, embankments

to support roads, and establishment of ponded pastures. There is a large dam on Forsyth

Creek that has a capacity of 35 000 ML (Forsyth Creek Dam). The development of

Forsyth Dam in 2005 created a significant abstraction of wet season flows within the

Forsyth Creek catchment, and has modified dry season conditions within both Forsyth and

Alligator Creek catchments. Water is released from this dam in the late dry season,

providing water for pasture growth over approximately 60 0000 ha of flood plain. This

water inundates the flood plain downstream, and is held in place by the bunds, for one or

two months, depending on the volume released (Water Technology 2016a).

Over the wet season, large areas of the low-lying flood plain slowly fill with water. These

areas are naturally relatively flat, and this, coupled with the aforementioned bunds,

embankments and roads, means that there is no significant drainage to the outlet creeks.

This forms ephemeral wetlands that dry out in the dry season (Water Technology 2016a).

The release from Forsyth Creek Dam in the dry season also inundates parts of these

ephemeral wetlands, increasing the period they function as wetlands (Water Technology

2016a).

Construction of Forsyth Creek Dam altered the natural hydrology of the system, capturing

wet season rainfall that would normally reach Forsyth Creek, and providing a source of

water in the dry season. Releases from Forsyth Creek Dam discharge into both the

Forsyth Creek and Alligator Creek catchments. The flow paths leading from the dam onto

the floodplain in these catchments have velocities up to 0.5 m/s and depths generally less

than 1.0 m. Once entering the respective floodplains, velocity and depth decreases as the

water spreads to fill the low-lying areas. The extent of inundation produced by the water

released from the dam is constrained by existing infrastructure, specifically the roadways

between the farms, which act as bunds. Water builds behind these roads before flow

paths are excavated, allowing water to be released into the lower catchment (Water

Technology 2016a). The area inundated by the release from the dam varies with the

amount of water released; however, it is significantly smaller than the area inundated in an

average wet season (Water Technology 2016a).

There are also a number of turkey nest dams on Legune Station, which fill with water in

the wet season, and decrease in volume in the dry season.

In the dry season, evaporation rates are high and all drainages above tidal influence are

reduced to unconnected waterholes. The majority of these waterholes are dry by

October, with only some (such as Alligator Spring) flowing during the dry season due to

spring flows (Tickel & Rajaratnam 1995). These waterholes and springs are important

refuge areas for fauna in an otherwise seasonally dry environment. The high rates of

frc environmental


evaporation also lead to increases in salinity in these water bodies (Water Technology

2016a).

Legune Station and its surrounds, as well as the adjoining marine environment, provide a

number of important environmental values for aquatic flora of fauna.

1.4 Existing Disturbances

The absence of broad scale intensive agriculture across northern Australia has left a large

area of tropical savannah largely intact. Most catchment vegetation and riparian zones in

northern Australia have not been cleared, although in most cases they have been

modified by weeds, changed fire regimes, feral animals and cattle grazing (Douglas et al.

2011). The diversity of animals is generally high by Australian standards, and is typically

distinctive, with many species widespread across northern Australia, but not extending

into the south (Douglas et al. 2011).

The Victoria River catchment has a low to moderate level of disturbance, with grazing the

major land use and cause of disturbance. Disturbances in the catchment include roads

and tracks; river crossings and watering points for stock; and feral animals. Weed

invasion of the riparian zone is the major issue affecting the condition of the Victoria River

and its tributaries (Kirby & Faulks 2004). Land uses in the Keep River catchment are also

dominated by grazing. There is also a large conservation area, the Keep River National

Park and Spirit Hills Wilderness Conservation Area (Map 1.1) (Kirby & Faulks 2004).

The Project area is remote with no major industrial development in the region and the

nearest population centre approximately 106 km to the south-west at Kununurra. The

Project site is a pastoral lease, which is currently primarily used for cattle grazing. Native

vegetation has previously been cleared over approximately 80 years and levee banks and

operational dams have been installed in a number of locations to maintain the improved

pasture species sown into the fenced paddocks network. Forsyth Creek Dam was also

built to improve the productivity of the coastal plains during the drier parts of the year and

to improve cattle production. There are currently approximately 30 000 cattle on the

station.

Cattle grazing can have a major impact on aquatic ecosystems via:

treading - physically damaging riparian and floodplain vegetation creating bare

ground and compacting (or pugging) soil, which can increase soil erosion and

water run-off, in turn increasing suspended sediments, turbidity and nutrients

delivered to waterways. Pugging can also create barriers to fish movements.

frc environmental


depositing urine and faeces – increasing nutrients and pathogens, and potentially

depleting dissolved oxygen levels

herbivory – consuming native flora, and

spreading invasive flora (Morris & Reich 2013).

Impacts of cattle grazing are likely to be highest during the transition from the dry to the

wet season when surface run-off is highest (Warfe et al. 2011).

K eep

River

A lligator Creek

Timor Sea

JosephBonaparte Gulf

FitzmauriceRiver

KeepRiver

VictoriaRiver

OrdRiver

oMary River(Proposed)

oSpirit Hills WildernessConservation Area

oLitchfield

oGregory

oKeepRiver

oDrysdaleRiver

oPurnululu

WoomeraCreek

Koolpin Creek

Pear Tree

Creek

Billy Goat Creek

Seven teenMile C reek

LakeArgyle

Stuart

Hi ghway

Arnhem Hig hway

Victoria

Hig hway

Great Nor ther n H ighway

Tanami Road

LeguneStation

RiverenStation

Newry Station

Berry Creek

West Baine s River

Victoria R iverTimberCreek

Barramundie C r eek

Sturt Creek

West B

aine sR

iver

D epot Creek

Frances Creek

Baines

Riv e

r

Allia Creek

D urackR i ver

Culle

n Riv e

r

Pentecost River

Salm ond River

Armstrong River

Docher ty Cre ek

Finni ssR i ver

Adela i

deRiv

erWilson River

Limestone Creek

King Geor

geRi

ver

Stirling Creek

Wi ld manRi

ver

Sturt Creek

Eva Creek

South All ig ator River

Ord R iver

Or d Ri ver

NegriRiver

Ma rgaret

Rive r

Hooker Creek

Be rk eley Rive r

Keep

R iver

Panton River

Bla ck fellow Cree k

Edith Riv e r

Palm Creek

Coolib

ah Creek

TurnerRive r

An ga larri Rive r

Behn River

Flora R iver

Stockade Creek

W ickham Rive r

Butto

nCree

k

Ka therineRiver

ErnestRi ver

Elvi re River

Ma thiso n Creek

Humbert River

Daly Ri ver

Sandy Creek

Alice Creek

O 'Donnell River

Hermit Creek

Horse Creek

Gregory Creek

Margaret River

Styles Creek

Bullo R iver

G B Creek

Cattle Creek

Fores

t Cree

k

Cui-Eci C

reek

SmokeCree

k

Reynolds River

Bindool aCre e k

Winnecke Creek

Behm River

Barry Cre ek

LaurieCr

eek

East Baines RiverSaddle Creek

Crawford Creek

Fergus s on R iver

Sandy Creek

Sku llCree

k

Foster Creek

Cow Cre ek

Surprise Creek

Cattle Creek

King River

King River

Wilson Creek

Vi ctoria River

Banjo Creek

Townsend Creek

Alp haC ree k

Bund

aCree

k

Marrakai Creek

Gree

n Ant

Creek

Giles Cr eek

Castl

er eag

hCr ee

k

Dick Creek

Maud Creek

Ikymbon River

Scott Creek

Cattle

Cr e ek

Johnst

onRiv

er

LauraC reek

Wandie

Creek

Mist a ke Creek

Bradsh

aw C reek

Macph

ee Cree

k

SandyCreek

Burre

llCree

k

Beta Cree k

WolfCreek East

Geo rge Creek

Leichhardt Creek

CowCreek

O'Donnell Brook

Muld iva Cre ek

Jasp er Creek

Swan Cree

k

Mary R iver

Moyle River

Gordy

Creek

GillCreek

H ayward

Cree

k

NiggerCre ek

PalmCreek

Str

a yCreek

D ryRiver

N icholson River

Osmond Creek

Delamere C reek

Little Go

l dRiv

er

Cam field River

Du nhamRiv er

Aroo na Creek

Bow Rive r

L innek

arCree

k

WestA

lli gator R

iver

Dougla s Ri ver

Howle

y C reek

Gordo

n Cree

k

Turkey

Creek

Watery R

iver

Laura River

Chamberlain Riv

er

Forre s tC r eekBattle Creek

FishRiver

Wes

ternCre ek

Fo rrest River

Mckin la yRiver

Mary River

Snake Creek

Giles Or Wattie Creek

Lily Creek

Dawn Creek

Wilson Creek

Bob Creek

Wildman River East Branch

Armanda River

Dingo Creek

Sundown Creek

Kimon Creek

Blackmore River

Wolf Creek

Glidden River

Middle Creek

Mcaddens Creek

Nourlangie Creek

Lalngang Creek

Burns Creek

Stallion Creek

Knox Creek

Surprise Creek

Kildurk Creek

Forrest Creek

Manton River

Cockatoo Creek

Soda Creek

Bamboo Creek

Ellenbrae Creek

Station Creek

Waterbag Creek

Saunders Creek

Figtree Creek

Parrot Creek

Jim Jim Creek

Howard River

Pine Creek

Adelaide River (West Branch)

Chilling Creek

Illawarra Creek

Poison Creek

Gipsy Creek

Hicks Creek

Fitzmaurice River

Coomalie Creek

Darwin River

Campbell Creek

Ullinger River

Campbell Creek

Christmas Creek

Fig Tree CreekMatilda Creek

Elizabeth River

Royston Creek

Wood River

Copperfield Creek

Moonbool Creek

Fitzroy River

Eight Mile Creek

Companion Creek

Finniss River South Branch

Chapman River

De Lancourt River

Upper Panton River

Tom Turners Creek

Johnson Creek

Gowonj (Coirwong) Creek

Bamboo (Moon Boon) Creek

Broadarrow Creek

132° E

132° E

130° E

130° E

128° E

128° E14

° S

14° S

16° S

16° S

18° S

18° S

PO Box 2363Wellington Point Q 4160 Australia

P 07 3286 3850 E [email protected]

Wes t Bain esRi

ver

VictoriaRiv e r

Fitzmaurice River

Ord River

Durac

kRi ver

Daly River

Kununurra

Vict oria

Hi ghway

G rea

tNor

th ernH

ighwa

y

±0 20 40 60 80 10010

Kilometres

SCALE

Scale: 1:2,200,000 @ A3

Coordinate System: GCS GDA 1994Datum: GDA 1994Units: Degree

PROJECTIONVERSION-CF

DRAWN BY

© Copyright Commonwealth of Australia (Geoscience Australia) 2001, 2004, 2006© Nearmap 2015

SOURCES

Project Sea Dragon

Map 1.1:Major catchments surrounding the project area

2016-07-01DATE

Document Path: Y:\Projects\2015\150911_CO2_PSD_October\Mapping\EIS\Workspaces\150911_Major_catchments.mxd

0 50 KmLEGENDLegune Station InternationallyImportant Bird AreaStationWA-NT State BorderNational Park

River CatchmentWatercourseLake/Reservoir

Highway / Major Road

2016-07-01

frc environmental


2 Methods

Data collection for this assessment consisted of two components: a desktop literature

review including liaison with key researchers and organisations, and field surveys.

2.1 Literature Review

Water quality, aquatic habitat, aquatic fauna (i.e. macroinvertebrates, fish and freshwater

turtles) and aquatic flora of the waterbodies on Legune Station and within the wider Keep

and Victoria River catchments were described through literature review. Sources included

the Commonwealth’s Department of Sustainability, Environment, Water, Population and

Communities (DSEWPC) online Environment Protection and Biodiversity Conservation

Act Protected Matters Search Tool, data from Northern Territory Government water quality

monitoring stations, other environmental impact assessments in the region and through

published scientific literature.

2.2 Field Surveys

The baseline surveys included assessment of:

water quality (measured in situ and samples collected for laboratory analyses)

sediment quality

freshwater macroinvertebrates

freshwater fish, and

freshwater turtles.

Initial Scoping Survey

Aquatic ecosystems on Legune Station were first surveyed at ten sites in the 2015 dry

season (10 to 19 June 2015). Results from this survey were used to design the baseline

monitoring programs for water quality and aquatic ecology (frc environmental 2015a; frc

environmental 2015b).

frc environmental


Survey Sites

In the first survey, in June 2015, ten sites on Legune Station were assessed. In the

following surveys, five sites were surveyed (Table 2.1, Map 2.1).

Timing of the Surveys

Water quality samples were collected for analysis on:

10 to 19 June 2015

11 August 2015

14 to 20 October 2015

15 to 20 January 2016, and

13 March 2016.

Aquatic ecology and sediment quality were assessed in three surveys:

10 to 19 June 2015 (dry season)

14 to 20 October 2015 (pre-wet season), and

10 to 21 March 2016 (post-wet season).

^

Keep

R ive

r

All iga to r Creek

Osman'sLake

JosephBonaparte GulfTurtle Point

Forsyth Creek Dam

High Water Inlet

Keep River

Napp

Springs Creek

Victoria River

Forsyth Creek

Sandy Creek

F01

F02

F15

F16

F17

F18

F03

F14

F19

F20

129.6° E

129.6° E

129.4° E

129.4° E

129.2° E

129.2° E15

° S

15° S

15.2°

S

15.2°

S

15.4°

S

15.4°

S

PO Box 2363Wellington Point Q 4160 Australia

P 07 3286 3850 E [email protected]

Wes t Bain esRi

ver

VictoriaRiv e r

Fitzmaurice River

Ord River

Durac

kRi ver

Daly River

Kununurra

Vict oria

Hi ghway

G rea

tNor

th ernH

ighwa

y

±0 105

Kilometres

SCALE

Scale: 1:200,000 @ A3

Coordinate System: GCS GDA 1994Datum: GDA 1994Units: Degree

PROJECTIONVERSION-CF

DRAWN BY

© Copyright Commonwealth of Australia (Geoscience Australia) 2001, 2004, 2006© Nearmap 2015

SOURCES

Project Sea Dragon

Map 2.1:Sites surveyed

2016-07-14DATE

Document Path: Y:\Projects\2015\150911_CO2_PSD_October\Mapping\EIS\Workspaces\150911_freshwater_sites_Mar16.mxd

0 50 KmLEGENDWater Quality, Ecology andSedimentStage 1 Footprint

^ Forsyth Creek Dam

WatercourseMajor WatercourseMinor WatercourseLake/Reservoir

2016-07-14

frc environmental


Table 2.1 Water quality and aquatic ecological sampling program.

June 15 Aug.15 October 15 Jan. 16 March 16

Site Latitude Longitude Description Water

Quality

Sediment

Quality

Macro-

inverts

Water

Quality

Water

Quality

Sediment

Quality

Macro-

inverts

Fish &

Turtles

Water

Quality

Water

Quality

Sediment

Quality

Macro-

inverts

Fish &

Turtles

F01 -15.17062 129.34354 Alligator Creek

upstream of tidal

influence, important

for waterbirds

X a – X – X X X X X Xb X X X

F02 -15.08223 129.39307 Ephemeral wetland X a – X – dry dry dry dry X Xb X X X

F03 -15.08242 129.39184 Turkey’s nest dam X b X X X – – – – – – – – –

F14 -15.07463 129.41932 Forsyth Creek,

upstream of direct

tidal influence. Used

by waterbirds

X b X X X X X X X X Xb X X X

F15 -15.06263 129.38854 Unnamed wetland X b X X – – – – – – – – – –

F16 -15.24218 129.31442 Osman’s Lake X b X X – – – – – – – – – –

F17 -15.20662 129.38450 Alligator Creek,

upstream site that is

important to

waterbirds

X b X X – X X X X X Xb X X X

F18 -15.21969 129.46143 Forsyth Creek Dam.

Water from the Dam

is released in the late

wet season

X b X X X X X X X X Xb X X X

F19 -15.00503 129.38529 Small unnamed

wetland near

saltmarsh / mudflat

X b X X – – – – – – – – – –

F20 -15.05301 129.37818 Large unnamed

wetland surrounding

a turkey’s nest dam

X b X X – – – – – – – – – –

X site surveyed

– site not surveyed

a only in situ measurements collected

b full assessment of water quality including metals and metalloids, pesticides and hydrocarbons

frc environmental


2.3 Water Quality Surveys

In each survey, with the exception of the survey in January 2016, water quality was

assessed at each site using a handheld Hydrolab Quanta water quality probe, and the

following data collected:

water temperature (°C)

pH

electrical conductivity (mS/cm)

dissolved oxygen (percent saturation and in mg/L), and

turbidity (Nephelometric turbidity units, NTU).

In addition water samples were collected from each site in each survey, with the exception

of sites F01 and F02 in June 2015. In each survey, with the exception of the January

2016 survey, samples were collected from the surface using a water bottle provided by

the laboratory attached to a sampling pole.

In January 2016 samples could only be collected using a helicopter, due to seasonal

flooding. Samples were collected from a helicopter, and decanted into appropriate water

bottles provided by the laboratory once on stable, dry land. As a consequence,

temperature and dissolved oxygen were not recorded in the January survey. Site F02

was dry in October 2015 and was consequently not sampled.

Water quality samples were analysed by a NATA-accredited laboratory (Table 2.2).

Toxicants were sampled twice: in June 2015 and in March 2016. It was considered that

given the land use and remoteness of the site, toxicants were unlikely to be significantly

influenced by anthropogenic impacts, and any changes in concentrations were likely to be

associated with seasonal variation.

Chemical and biological oxygen demand were analysed in March 2016, to give an

indication of the amount of dissolved oxygen needed to breakdown organic material in the

water body. The species composition of phytoplankton was also analysed in March 2016.

frc environmental


Table 2.2 Summary of water quality assessments.

Parameter Jun-15 Aug-15 Oct-15 Jan-16 Mar-16

temperature X X X – X

electrical conductivity X X X X X

pH X X X X X

dissolved oxygen X X X – X

turbidity X X X X X

total suspended solids X X X X X

total dissolved solids X X X X X

total nitrogen X X X X X

ammonia X X X X X

oxides of nitrogen X X X X X

Kjeldahl nitrogen X X X X X

total phosphorous X X X X X

reactive phosphorous X X X X X

total organic carbon X X X X X

chlorophyll a X X X X X

total and dissolved metals and metalloids X – – – X

total recoverable hydrocarbons X – – – X

organochlorine pesticides X – – – X

organophosphorous pesticides X – – – X

chemical oxygen demand – – – – X

biological oxygen demand – – – – X

phytoplankton – – – – X

frc environmental


Quality Control / Quality Assurance

All sampling was in accordance with the Queensland Monitoring and Sampling Manual

2009 (DERM 2010)1.

The water quality probe was calibrated at the beginning and end of each trip, and checked

daily and re-calibrated, if required.

Water samples were collected using the water bottles provided by the laboratory. In each

survey, two samples were collected from at least one site to assess within site variation.

One field blank was also collected to assess variation due to handling. All samples were

analysed by a NATA-accredited laboratory, and included further laboratory quality

assurance procedures.

Samples were chilled, stored in the dark and delivered to the laboratory as soon as

possible (<10 days).

Data Analysis

Water quality data was tabulated and compared to the laboratory limits of reporting and

trigger values in the Australian Water Quality Guidelines (AWQG, ANZECC & ARMCANZ

2000). Data was also graphed to show temporal trends. Where possible, the laboratory

limit of reporting (LOR) was less than or equal to the applicable AWQG; however, these

were not always achieved, in part due to due to matrix interference, and in particular high

concentrations of total dissolved solids.

The AWQG recommend three methods for dealing with LOR that are above the AWQG in

statistical analyses:

excluding the data from data analysis

using a value half the LOR in analysis, or

using the LOR in analysis.

With the exception of chlorophyll a, where data was below LOR, values were halved prior

to data analysis. This is consistent with the approach taken in previous analysis of water

quality data in the Keep River (Bennett & George 2014), which was endorsed by an

independent review group for this work. The half LOR approach is considered to be

conservative, as the other two methods tend to artificially increase the derived baseline

1 There are no specific guidelines for water quality monitoring methods for the Northern Territory.

frc environmental


concentrations (Bennett & George 2014). Due to frequent and high interference with the

matrix for chlorophyll a, values were excluded when the LOR was higher than 1 µg/L.

Where data for turbidity, pH and EC was recorded in both the laboratory and the field,

data recorded in the laboratory was used in analyses.

The median concentrations of physical and chemical stressors were compared to the

AWQG, except where only one sample was collected, in which case the concentration in

that sample was compared to the AWQG. The concentrations of toxicants were analysed

in samples collected in June 2015 and March 2016. The maximum concentration of each

toxicant was compared to the AWQG. Where the maximum was less than the LOR, this

was recorded in the table of comparisons.

2.4 Sediment Quality

Sediment quality was assessed in three surveys:




In June and October 2015, one sample was collected from each site that was surveyed.

In March 2016, three samples were collected from each site, to assess variation within

sites.

Sediment was collected using a stainless steel trowel from approximately 0.3 m below the

surface of the water, at the waters edge. All sediments were transferred directly into the

analytical containers provided by the laboratory. Sediment samples were analysed by a

NATA-accredited laboratory for:

particle size distribution

total metals and metalloids

nutrients

total recoverable hydrocarbons, and

pesticides.

frc environmental


Data Analysis

Sediment quality was compared to the laboratory limits of reporting and the trigger values

in the Revision of the ANZECC/ARMCANZ Sediment Quality Guidelines (Simpson et al.

2013).

2.5 Macroinvertebrate Communities

Macroinvertebrate communities are an important part of aquatic ecosystems and are key

components of many aquatic food webs. They also directly influence many aquatic

ecological processes, such as primary production, sedimentation and the processing of

organic matter (e.g. shrimps and crabs). As a consequence, macroinvertebrate

communities are used as the key indicator group for bio-assessment of the health of

Australia’s streams, rivers and waterways.

The use of macroinvertebrates in Australia as indicators for river health was developed as

a part of the Monitoring River Health Initiative and the Australian River Assessment

Scheme; and has been adopted in the Northern Territory (Lloyd & Cook 2002). In the

Northern Territory, macroinvertebrates are commonly used as indicators of changes to

water quality, due to their abundance, diversity, sensitivity to changes in water quality

(including slow re-colonisation after a pollution event), and good taxonomic knowledge

(Lloyd & Cook 2002).

Macroinvertebrate communities were assessed in three surveys:




Five macroinvertebrate samples were collected from edge habitat at each site. Sediment

was disturbed within a 30 x 30 cm area for five seconds, and each sample was collected

sweeping a standard triangular-framed, macroinvertebrate sampling net (with 250 µm

mesh) through the disturbed area five times.

All macroinvertebrate samples were preserved with methylated spirits and returned to

frc environmental’s biological laboratory where they were sorted, counted and identified to

the lowest practical taxonomic level (in most instances family), to comply with AUSRIVAS

standards and those described by Chessman (2003).

frc environmental


For quality assurance / quality control procedures, 10% of all macroinvertebrate samples

were re-identified and re-counted and 10% of the data was re-entered by an ecologist

other than the one who completed the original identifications and data entry.

Data Analyses

Community differences between sites and between surveys were illustrated using

non-metric multidimensional scaling plots. Non-metric multidimensional scaling attempts

to place samples on a plot, so that the rank order of the distances among samples

matches the rank order of the matching similarities from the similarity matrix (Clarke &

Warwick 2001). This provides a visual representation of the similarities among

communities within each sample. However, the axes are not related to particular values.

The macroinvertebrate data was also interpreted using water and sediment quality data,

using the BIOENV routine, which can allow the identification of variables that may explain

distribution and abundance patterns.

A suite of macroinvertebrate indices was used to provide a rapid assessment of

ecosystem health. The indices that were calculated were:

abundance

taxonomic richness

Stream Invertebrate Grade Number – Average Level (SIGNAL 2) scores, and

Plecoptera / Ephemoptera / Trichoptera (PET) richness.

Abundance

Abundance is the total number of macroinvertebrates sampled.

Taxonomic Richness

Taxonomic richness is the number of taxa (in this assessment, families). Taxonomic

richness is a basic, unambiguous and effective diversity measure. However, it is affected

by arbitrary choice of sample size. Where all samples are of equal size, taxonomic

richness is a useful tool when used in conjunction with other indices. Richness does not

take into account the relative abundance of each taxon, so rare and common taxa are

considered equally.

frc environmental


PET Richness

While some groups of macroinvertebrates are tolerant to pollution and environmental

degradation, others are sensitive to these stressors (Chessman 2003). Plecoptera

(stoneflies), Ephemeroptera (mayflies), and Trichoptera (caddisflies) are referred to as

PET taxa, and they are particularly sensitive to disturbance. There are typically more PET

families within sites of good habitat and water quality than in degraded sites. PET taxa

are often the first to disappear when water quality or environmental degradation occurs

(EHMP 2007). The lower the PET score, the greater the inferred degradation.

PET richness is an index used Australia wide. However Plecoptera are largely restricted

to cool stenothermic environments, and are rarely found in Northern Australia (Garcia et

al. 2011), and consequently PET scores in tropical regions will be lower than in temperate

regions. PET scores were interpreted accordingly.

SIGNAL 2 Scores

SIGNAL 2 scores are based on the sensitivity of each macroinvertebrate family to

pollution and / or habitat degradation. The SIGNAL system has been under continual

development for over 10 years, with the current version known as SIGNAL 2. Each

macroinvertebrate family has been assigned a grade number between one and ten based

on their sensitivity to various pollutants. A low number means that the macroinvertebrate

is tolerant of a range of environmental conditions, including common forms of water

pollution (e.g. suspended sediment and nutrient enrichment).

SIGNAL 2 scores are weighted for abundance and the scores take the relative abundance

of tolerant or sensitive taxa into account (instead of only the presence or absence of these

taxa). The overall SIGNAL 2 score for a site is based on:

the total of the SIGNAL grade

multiplied by the weight factor for each taxon, and

divided by the total of the weight factors for each taxon.

2.6 Fish

To assess the fish communities on the station, baited traps were set overnight In October

2015 and March 2016.

frc environmental


The total catch was counted and specimens photographed before being released at the

survey site. The trapping effort was supplemented by field observations and photographs

of fish caught using hook and line. Fish were handled in accordance with the Northern

Territory’s Department of Primary Industry and Fisheries permit number 2014-

2015/S17/3366 and scientific permit number 54947 issued to frc environmental.

2.7 Reptiles

To assess the population of freshwater turtles, baited cathedral traps were set overnight in

March 2016. Any turtles that were caught were identified, photographed and returned to

the environment.

Crocodiles were surveyed visually at each site and sightings recorded.

2.8 Limitations and Constraints

Due to the threat posed by crocodiles, the number of traps set for fish and freshwater

turtles were limited. Fish and turtles were not surveyed in January 2016, as the high

water prevented access, and the ground was unsuitable for a helicopter to land on. Water

quality samples were collected using a helicopter in January 2016, and consequently in

situ readings of temperature and the concentration of dissolved oxygen were not

recorded.

frc environmental


3 Legislation

3.1 Environmental Protection and Biodiversity Conservation Act 1999

The Environmental Protection and Biodiversity Conservation Act 1999 (the EPBC Act)

provides protection for Australia’s biodiversity. Nine Matters of National Environmental

Significance (MNES), are protected under this Act:

world heritage properties

national heritage places

wetlands of international importance

nationally threatened species and ecological communities

migratory species

Commonwealth marine areas

Great Barrier Reef Marine Park

nuclear actions (including uranium mining), and

a water resource in relation to coal seam gas development and large coal mining

development.

Any actions that are likely to have a significant impact on an MNES are subject to

assessment under the EPBC Act approval process.

The following aquatic MNES were listed on the EPBC Act protected matters search report

as potentially occurring within 10 km of the Project:

nationally threatened species and ecological communities, and

migratory species.

The Great Barrier Reef Marine Park, nuclear actions and coal seam gas development are

not relevant to this Project.

Commonwealth marine waters include the area from the edge of the state coastal waters

(3 nautical miles) out to 200 nautical miles from the coast. Commonwealth marine areas

are MNES under the EPBC Act. The Project is more than 20 km from Commonwealth

marine waters and is considered highly unlikely to impact this area (frc environmental

2016).

frc environmental


World Heritage Properties

The EPBC Act regulates actions that will, or are likely to, have a significant impact on the

world heritage values of a World Heritage Property. This includes relevant actions that

occur outside the boundaries of a World Heritage Property. The closest World Heritage

property is the Purnululu National Park, which is approximately 280 km south of the

Project area in the Ord River catchment in Western Australia. The Project will have no

impact on the aquatic ecological values of this or any other World Heritage Property.

National Heritage Places

Natural heritage places include natural, historic and indigenous places of outstanding

heritage value. The closest national heritage places are Purnululu National Park and the

Wave Hill Walk-Off Route. The Wave Hill Walk-Off Route is approximately 320 km south

of the Project area in the Victoria River catchment. The Project will have no impact on the

aquatic ecological values of these national heritage places.

Wetlands of International Importance (Ramsar Wetlands)

The EPBC Act regulates actions that will, or are likely to have a significant impact on the

ecological character of a Ramsar wetland (wetlands of international significance). This

includes relevant actions that occur outside the boundaries of a Ramsar wetland. The

closest Ramsar wetland is the Ord River floodplain located approximately 90 km west of

the Project area in the Joseph Bonaparte Gulf. The Project will have no impact on the

aquatic ecological values of this Ramsar wetland.

Threatened Species and Ecological Communities

No threatened aquatic ecological communities were listed within 10 km of the Project.

Fourteen aquatic fauna species were listed as threatened and/or migratory species in the

EPBC Act protected matters report as potentially occurring within 10 km of the Project. As

these species are predominantly marine or estuarine (e.g. sawfish), they are discussed in

the Project Sea Dragon Stage 1: Environmental Impact Statement Estuarine Receiving

Environment report (frc environmental 2016).

frc environmental


3.2 Environmental Offsets Policy 2012

Under the EPBC Act Environmental Offsets Policy, environmental offsets are actions

taken to counterbalance significant residual impacts on protected Matters of National

Environmental Significance (MNES). Offsets are meant to be used as a last resort where

an action will lead to residual impacts, even after the application of mitigation measures.

The policy provides guidance on the role of offsets in environmental impact assessments

and how the Department of the Environment considers the suitability of proposed offsets

(SEWPAC 2012). Offsets may comprise a combination of direct (e.g. restoring degraded

land to provide habitat) and / or indirect (e.g. contributing to research that benefits an

impacted species or community).

3.3 Northern Territory’s Territory Parks and Wildlife Conservation Act

The Territory Parks and Wildlife Conservation Act (TPWC Act) provides conservation

categories for aquatic species. Fish species listed under the TPWC Act are protected

under the Northern Territory’s Fisheries Act. Freshwater fish and turtles listed under the

TPWC and the likelihood of these species occurring in the Project area are shown in

Table 3.1. Overall, the Angalarri grunter (listed as vulnerable), Obbes’ catfish (listed as

near threatened) and the pig-nosed turtle (listed as near threatened) are moderately likely

to occur in the Project Area. These species are discussed further in Section 7.

As the potentially occurring sawfish, river shark, marine mammals and marine reptiles are

predominantly marine or estuarine, they are discussed in the Project Sea Dragon Stage 1:

Environmental Impact Statement Estuarine Receiving Environment report (frc

environmental 2016).

frc environmental


Table 3.1 Likelihood of fish and turtle listed as threatened under the TPWC occurring

near the proposed development.

Species Common

Name TPWC Act Comments

Likelihood

of

Occurrence

Chlamydogobius

japalpa

Finke goby Vulnerable Limited distribution in the

upper reaches of the Finke

River system

Low

Pingalla lorentzi Lorentz

grunter

Vulnerable Only known in Australia from

the Finnis River near the

Rum Jungle mine site

Low

Scortum neili Angalarri

grunter

Vulnerable Recorded in the Victoria

River

Moderate

Pristis zijsron Finke

hardyhead

Near

threatened

Limited distribution in the

Finke River system

Low

Melanotaenia

maccullochi

McCulloch’s

rainbowfish

Near

threatened

Within geographic range, but

no suitable habitat (clear

waters of small creeks and

Pandanus swamps with low

pH) on site

Low

Mogurnda

larapintae

desert

mogurnda

Near

threatened

Within distributional range

but no suitable habitat (rocky

waterholes) on site

Low

Porochilus obbesi Obbes’

catfish

Near

threatened

Broad known range in

Northern Australia

Moderate

Carettochelys

insculpta

pig-nosed

turtle

Near

threatened

Recorded in the Victoria

River, but is restricted to river

channels

Low to

moderate

Site of Conservation Significance

Under the Northern Territory Government, the Legune coastal floodplain is considered a

site of conservation significance, and has an international significance rating (NT

Government 2016). This is due to the high ecological values of the wetland habitats,

wader bird and migratory shorebird populations and to the flatback turtle rookery at Turtle

Point (Map 1.1).

frc environmental


3.4 Northern Territory’s Fisheries Act

The Fisheries Act provides for the protection, conservation and management of fish, fish

habitats and aquatic life in the Northern Territory. One fish listed under this Act has been

recorded from the Victoria River catchment: the Angalarri grunter (Scrotum neili), which is

listed as vulnerable. The Angalarri grunter is known from the Angalarri River and one

individual recorded in the East Baines River, both within the Victoria River catchment.

This species is restricted to deep, wide pools with overhanging vegetation and a rocky

substrate (Woinarski 2006). This species is unlikely to be in the vicinity of the Project area

due to lack of suitable habitat.

No other freshwater aquatic species protected under the Fisheries Act are likely to occur

in the vicinity of the proposed project.

Some listed sawfish may use freshwater throughout their life cycle. These are discussed

in the Project Sea Dragon Stage 1: Environmental Impact Statement Estuarine Receiving

Environment report (frc environmental 2016).

3.5 Northern Territory’s Water Act

The Water Act and Water Regulation provide the legislative framework for water planning

and entitlements for most water resources in the Northern Territory. The Water Act

provides for the investigation, allocation, use, control, protection and management of

surface water and groundwater resources. The Project is not within a declared Water

Control District nor a Water Allocation Planning Area.

Pollution under the Water Act includes directly or indirectly altering the physical, thermal,

chemical, biological or radioactive properties of the water making it unfit for a prescribed

beneficial use or to cause a condition which is hazardous or potentially hazardous to:

public health, safety or welfare

animals, birds, fish or aquatic life, and

plants.

Site drainage infrastructure should be designed in accordance with relevant engineering

guidelines and national standards. Approvals are required for dam structures and

watercourse diversions.

frc environmental


3.6 Northern Territory’s Environmental Assessment Act

The Environmental Assessment Act sets out the process for environmental assessments

of proposed actions and determines if the actions are capable of having a significant

impact on the environment.

frc environmental


4 Overview

Aquatic habitats around Legune Station include:

freshwater creeks

spring-fed waterholes

tidally inundated creeks

ephemeral wetlands (Figure 4.1), and

man-made dams, including turkey’s nest dams (Figure 4.1 and Figure 4.2).

The ephemeral wetland areas are predominantly created by overland flows, and dry out in

the dry season. The area is subject to periods of heavy rainfall and flooding in the wet

season, with large variations in water flows and levels. Overall, the wet season causes

large swathes of floodplain to slowly fill with water. These areas are relatively flat and do

not allow significant drainage to the outlet creeks. In the dry season, large areas of

ephemeral wetlands dry, leaving fauna stranded (Figure 4.3).

In the late dry season (i.e. from July to September) water is released from Forsyth Creek

Dam (site F18) and flows into the Forsyth and Alligator Creek catchments. Once entering

the respective floodplains, velocity and depth decreases as the water spreads to fill the

low-lying areas. The extent of inundation produced by the water released from the dam is

constrained by existing infrastructure, specifically the roadways between the farms, which

act as bunds. Water builds behind these roads before flow paths are excavated, allowing

water to be released into the lower catchment (Water Technology 2016b). The area

inundated by the release from the dam varies with the amount of water released;

however, it is significantly smaller than the area inundated in an average wet season

(Water Technology 2016b). Dam releases re-establish wet season water quality

conditions in the late dry season for one to two months depending on the volume

released.

The habitat at each site that was sampled for the Project is summarised in Table 4.1.

frc environmental


Figure 4.1

Turkey’s nest dam and

surrounding wetland area in the

wet season (January 2016).

Figure 4.2

Forsyth Creek Dam on the

southern end of Legune Station in

the post-wet season (March

2016).

Figure 4.3

Skeleton of dead fish likely to

have been stranded in the dry

season.

frc environmental


Table 4.1 Aquatic habitat at each site

Site Description Photographs

F01

Alligator Creek

This site was a wide, shallow part of Alligator Creek upstream of tidal influence. There is a road

crossing that impedes flow and fish passage. The banks were low and sloping, and bed

substrate was a mixture of boulders, cobbles, pebbles, gravel, sand and silt / clay. The riparian

vegetation was highly disturbed as adjacent land was cleared for grazing. There were dense

aquatic plants in-stream including sedges (Cyperus spp.), cumbungi (Typha sp.) and

ribbonweed (Vallisneria nana). Aquatic habitat was of moderate value and included aquatic

plants, detritus, large woody debris and rocks. There was evidence of bird activity at this site.

View of right bank in June 2015.

View downstream in October 2015.

View downstream in January 2016.

View upstream in June 2015.

View upstream in October 2015.

frc environmental



F02

Ephemeral

wetland

The site was a large ephemeral wetland surrounding a turkey’s nest dam. The banks were low

and sloping, and bed substrate was dominated by silt / clay. The riparian vegetation was highly

disturbed as adjacent land was cleared for grazing. There were some waterlilies (Nymphaea

violacea) scattered around the site, but no other aquatic plants were recorded. Aquatic habitat

was of low value and limited to aquatic plants and detritus. There was evidence of bird activity

at this site.

View west towards turkey’s nest dam in June 2015.

View west towards turkey’s nest dam in October 2015.

View west towards turkey’s nest dam in January 2016.

F03

Turkey’s nest

dam

This site was a turkey’s nest dam used for stock watering. The banks were convex with bed

substrate dominated by silt / clay. The riparian vegetation was highly disturbed as adjacent land

was cleared for grazing. There were some submerged aquatic plants, predominantly

ribbonweed (Vallisneria nana). Aquatic habitat was of relatively low value and comprised

detritus, aquatic plants and a deep pool. There was evidence of bird accessing the site for

foraging.

View of turkey’s nest dam in October 2015.

Wallabies drinking from the turkey ’s nest dam in

October 2015.

frc environmental



F14

Forsyth Creek

This site was a wide, shallow section of the creek upstream of the road crossing. The road

crossing was identified as the limit of tidal influence from the estuarine reaches of Forsyth

Creek. Banks were low and sloping, and bed substrate was dominated by silt / c lay. The

riparian vegetation was highly disturbed as adjacent land was cleared for grazing. There were

no aquatic plants recorded at this site. The value of aquatic habitat was low and comprised pool

and rocks around the road crossing. There were some filamentous algae along the waters edge

in each survey. There was evidence of bird activity at this site. Crocodiles were observed at this

site in each survey.

View upstream in June 2015.

View upstream in October 2015.

View upstream in March 2016.

F15

Unnamed

wetland

This site was a small wetland area that was reduced to several small isolated pools in June

2015. The banks were low and sloping, and bed substrate was dominated by silt / clay. The

riparian vegetation was highly disturbed as adjacent land was cleared for grazing. There were

some emergent spike rushes (Eleocharis sp.) scattered around the area. Aquatic habitat was of

low value and limited to aquatic plants with some detritus. There were algae growing in the

smaller pools, particularly in depressions made by cattle tracks. There were several large fish

bones at this site, indicating fish use in the wet season when the area is inundated.

June 2015

Isolated pool, June 2015

frc environmental



F16

Osman’s Lake

This site was a large lake in the south-west corner of Legune Station. The banks were low and

sloping, bed substrate was dominated by silt / clay sediments that was easily dislodged and

available for transport in periods of high flow. The riparian vegetation was highly disturbed as

adjacent land was cleared for grazing. There were no aquatic plants observed on the banks and

there was little habitat available for aquatic fauna. There was evidence of bird activity at this

site.

View west towards Osman’s Lake in June 2015.

View south-west towards Osman’s Lake in January

2016.

F17

Alligator Creek

This site was a wide, shallow creek with intermittent flow. There was no flow in the June 2015

survey; however, in March 2016 the flow was approximately 0.3 m/s and overtopping the road

crossing. The creek was mildly sinuous with low sloping banks. Bed sediment was a mixture of

boulders, cobbles, pebbles, gravel, sand and silt / clay. The riparian vegetation was highly

disturbed as adjacent land was cleared for grazing. There were dense aquatic plants along the

bank edges and also submerged plants in the water column. Common aquatic plants included

spikerush (Eleocharis sp.), ribbonweed (Vallisneria nana) and waterlilies (Nymphaea violacea).

There were a variety of in-stream habitats comprising aquatic plants, small woody debris,

detritus, rock faces and man-made structures. There was evidence of bird activity at this site.

View downstream in June 2015.

View downstream in October 2015.

View downstream in March 2016.

frc environmental



F18

Forsyth Creek

Dam

This site was a large, man-made dam on Forsyth Creek, south of the Legune homestead.

Water is released from the dam annually in the late dry season and water levels are highly

influenced by rainfall throughout the year. The banks were moderate and concave and bed

sediment comprised a variety of substrates. The riparian vegetation was moderately disturbed

with the north section cleared of vegetation for the access track; however, the remaining banks

had relatively intact native vegetation. No aquatic plants were recorded in June 2015; however,

in March 2016 there were some sedges (Cyperus spp.) and waterlilies (Nymphaea violacea).

Aquatic habitat was minimal and limited to aquatic plants, detritus and rock faces, with some

trailing root vegetation depending on water levels in the dam.

View south in June 2015.

View north-east in October 2015.

View north-east in March 2016.

View south in October 2015.

F19

Unnamed

wetland

This site was a small wetland near the saltmarsh / mangrove margins on the north end of

Legune Station. Banks were low and sloping, and bed substrate was dominated by silt / clay.

The riparian vegetation was highly disturbed as adjacent land was cleared for grazing. There

were no aquatic plants recorded at this site. The value of aquatic habitat was low and the site

was reduced to several small interconnected pools that were unlikely to hold water for long.

There was evidence of bird activity at this site.

View south in June 2015.

View south-east in June 2015.

frc environmental



F20

Unnamed

wetland

This site was a large wetland area surrounding a turkey’s nest dam. The banks were low and

sloping, and bed substrate was dominated by silt / clay. The riparian vegetation was highly

disturbed as adjacent land was cleared for grazing. There were some aquatic plants scattered

throughout the wetland including waterlilies (Nymphaea violacea), emergent club rushes

(Schoenoplectus sp.) and submerged elodea (Elodea canadensis). Aquatic habitat was of low

value and limited to aquatic plants with some detritus. Crocodiles were observed at this site in

June 2015 and March 2016.

View west towards the turkey’s nest in June 2015.

View north in June 2015.

frc environmental


5 Water Quality

Freshwater water bodies in the area are characteristically ephemeral, filling in the wet

season and drying out in the dry season. While there are extensive floodplains in the wet

season, in the dry season surface water is confined to small channels, billabongs and

swamps. These water bodies gradually evaporate, becoming stagnant and commonly

drying out. Storms in the early wet season result in turbid ‘flushes’ from surface run-off

from the catchment, from stagnant pools in the riverbed, and from previously dried up

water bodies (Townsend et al. 1992). These flushes are further characterised by high

concentrations of decayed organic matter, high bacterial pollution and low oxygen content,

often resulting in a rapid deterioration of water quality (frc pers. obs.).

The Keep and Victoria River catchments, splitting Legune Station approximately in half

north to south, are subject to high fluctuations in salinity, turbidity and nutrient

concentrations between and within the seasonal changes of dry and wet seasons.

Electrical conductivity and turbidity in the Victoria River catchment at times exceeds

AWQG (Kirby & Faulks 2004). Electrical conductivity throughout the catchment ranged

from 23 to 19300 µS/cm, while median turbidity ranged from 1 to 5000 NTU (Kirby &

Faulks 2004). However, relatively little data has been collected, with the frequency and

cause of these exceedances unclear. The variability and high values may be due to

natural factors (Kirby & Faulks 2004). The pH throughout the catchment was mostly

between 7 and 8, and within the AWQG. Total phosphorous levels were typically low

ranging from 0.009 to 0.03 mg/L (Kirby & Faulks 2004).

Water quality in the upper Keep River has been surveyed in relation to expansions of the

Ord River Irrigation Area (ORIA). In the dry season, the Keep River system was

characterised by moderate to high concentrations of dissolved oxygen, pH between 6.0

and 9.2, and water temperatures between 18°C and 34.2°C. On occasion, total

phosphorus and total nitrogen were above AWQG trigger values for unmodified, high

conservation/ecological value, lowland river systems in tropical Australia (Bennett &

George 2011). There was considerable variation in salinity, turbidity and the

concentration of nutrients both between and within seasons (Bennett & George 2014). In

the dry season, in a downstream pool, electrical conductivity ranged between 1388–3950

mS/cm (i.e. over 20 time the salinity of seawater) and in an upstream pool ranged

between 16–87 mS/cm indicating a highly variable environment which experiences

impacts from tidal flushing and high evaporation with concentration of salts in the

remaining water (Bennett & George 2011). The concentration of total nitrogen was also

highly variable, for example ranging between 0.09 to 0.64 mg/L at one site (Bennett &

George 2011).

frc environmental


In the Keep River in the 2010/2011 wet season, total nitrogen and phosphorous

concentrations were up to 10–100 times the AWQG trigger values, while electrical

conductivity ranged between 5–31 mS/cm (Bennett & George 2011). The concentration

of several dissolved metals, including aluminium, cadmium and copper, were above

AWQG in both the wet and dry seasons, while lead was only above the AWQG in the wet

season (Bennett & George 2014). Further, the lower Keep River recently changed from a

seasonally flowing stream to a perennial stream due to changes in rainfall and

groundwater conditions (Bennett & George 2011).

In permanent pools in the Keep River, the concentration of total nitrogen and phosphorous

were commonly elevated (WRM 2010; WRM 2014).

It has been recommended that the Keep River should be classified as a slightly to

moderately modified system (Category 2; Bennett & George 2011). This classification is a

result of natural (i.e. tidal, climate variability and groundwater discharge) as well as

anthropogenic factors (i.e. rangeland and grazing), impacting the Keep River.

5.1 Water Quality of Water Bodies on Legune Station

Physical and Chemical Stressors

Water quality in the water bodies on Legune Station was generally characterised by:

warm water

pH that was commonly high

percent saturation of dissolved oxygen that was commonly moderately low (i.e.

below AWQG)

very low concentration of dissolved oxygen in October 2015 when water levels

were also low

high chlorophyll a, and

nutrients that were commonly high (Figure 5.1 to Figure 5.8 and Table 5.1).

Alligator and Forsyth Creek sites (Sites F01, F14 and F17)

Water quality was relatively poor in these creeks, with:

frc environmental


median values of dissolved oxygen, pH, turbidity, electrical conductivity,

chlorophyll a, total nitrogen, ammonia and oxides of nitrogen not complying with

AWQG (except for dissolved oxygen at Alligator Creek site F01, which just

complied with AWQG)

very low percent saturation of dissolved oxygen (< 20%) in the dry season (June

2015) and pre-wet season (October 2015) at site F14

predominantly high turbidity, with very high turbidity at site F14 in Forsyth Creek in

dry season (June 2015) , and

high total nitrogen particularly in the dry and pre-wet seasons.

There was also very high electrical conductivity at site F14 in Forsyth Creek, likely due to

tidal influence and evaporation.

Reservoirs: Forsyth Creek Dam (Site F18) and Turkey’s Nest Dam (Site F03)

In Forsyth Creek dam the percent saturation of dissolved oxygen was very low (< 20%) in

the pre-wet season (October 2015). Live fish were observed in the dam at this time, so

this low percent saturation of dissolved oxygen may have been limited to the edge of the

dam, where the reading was taken. The concentrations of ammonia and total

phosphorous were particularly high in the early dry season (June 2015); however, in the

mid dry season (August 2015) concentrations were lower and below the AWQG.

Ammonia and total phosphorous increased slightly in October, and were lower in the wet

and post wet season (January and March 2016). The concentration of oxides of nitrogen

was over the AWQG at this site, except in October 2015. The concentration of chlorophyll

a was also relatively high in October 2015 indicating elevated primary productivity in the

pre-wet season.

The turkey’s nest dam was sampled for water quality in June and August 2015. In June

2015, water quality was relatively poor, with low dissolved oxygen, and high

concentrations of nitrogen and ammonia.

In August 2015, dissolved oxygen was high; however, the concentration of nitrogen and

oxides of nitrogen were over AWQG.

frc environmental


Wetlands (Site F02, F15, F16, F19 and F20)

Site F02 was sampled in June 2015 (in situ measurements only), and in January and

March 2016. This site was dry in October 2015. In this ephemeral wetland, the water

quality was relatively poor to moderate, with

low (31%) to moderate (69%) percent saturation of dissolved oxygen in the dry

(June 2015) and wet season (March 2016), respectively

high turbidity in the dry season

high pH, and

high concentration of ammonia in January 2016 (Table 5.1).

Water quality was assessed at the remaining wetland sites in June 2015. Water quality

was relatively poor at these sites at this time with low dissolved oxygen, and with pH,

turbidity, electrical conductivity, total nitrogen and total phosphorous over AWQG.

Figure 5.1 Percent saturation of dissolved oxygen at each site in each survey.

– – – – – – – – – – – – – – – – – – – – – – – – – – – – 0

20

40

60

80

100

120

F01 Alligator Ck

F14 Forsyth Ck

F17 Alligator Ck upstream

F03 Turkey's Nest Dam

F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland

Lowland River Reservoir Wetland

Dis

so

lved

Oxyg

en

(%

satu

rati

on

)

Jun-15

Aug-15

Oct-15

Jan-16

Mar-16

frc environmental


Figure 5.2 Turbidity at each site in each survey.

Figure 5.3 Electrical conductivity at each site in each survey.

– – – – – – – – – – – – – – – – – – – – – – – 0

200

400

600

800

1000

1200

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Tu

rbid

ity (

NT

U)

Jun-15

Aug-15

Oct-15

Jan-16

Mar-16

– – – – – – – – – – – – – – – – – – – – – – – 0

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Ele

ctr

ical C

on

du

cti

vit

y (µ

S/c

m)

Jun-15

Aug-15

Oct-15

Jan-16

Mar-16

frc environmental


Figure 5.4 Concentration of total nitrogen at each site in each survey.

Figure 5.5 Concentration of oxides of nitrogen at each site in each survey.

– – – – – – – – – – – – – – – – – – – – – – – – – 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


To

tal N

itro

ge

n a

s N

(m

g/L

)

Jun-15

Aug-15

Oct-15

Jan-16

Mar-16

– – – – – – – – – – – – – – – – – – – – – – – – – 0

0.02

0.04

0.06

0.08

0.1

0.12

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Ox

ides o

f N

itro

gen

as N

(m

g/L

)

Jun-15

Aug-15

Oct-15

Jan-16

Mar-16

frc environmental


Figure 5.6 Concentration of ammonia at each site in each survey.

Figure 5.7 Concentration of total phosphorus at each site in each survey.

– – – – – – – – – – – – – – – – – – – – – – – – – 0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Am

mo

nia

as

N (

mg

/L)

Jun-15

Aug-15

Oct-15

Jan-16

Mar-16

– – – – – – – – – – – – – – – – – – – – – – – – – 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


To

tal P

ho

sp

ho

rus (

mg

/L)

Jun-15

Aug-15

Oct-15

Jan-16

Mar-16

frc environmental


Figure 5.8 Concentration of chlorophyll a at each site in each survey.

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 0

20

40

60

80

100

120

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Ch

loro

ph

yll a

(µ

g/L

)

Jun-15

Aug-15

Oct-15

Jan-16

Mar-16

frc environmental


Table 5.1 The physical and chemical stressors at each site compared to the relevant AWQG a, b.

Parameter Units LOR Range Lowland Rivers Reservoirs Wetlands

AWQG F01 F14 F17 AWQG F03 F18 AWQG F02 F15 F16 F19 F20

Physical Stressors

water temperature ° C – – 29.2 28.5 33.3 – 24.8 30.2 – 28.1 29.6 29.0 22.2 23.5

dissolved oxygen % saturation – 85–120 86 39 81 90–120 66 83 80–110 50 45 80 27 29

pH pH units – 6.0–8.0 8.6 8.3 8.1 6.0–8.0 9.3 7.4 6.0–8.0 8.7 8.9 9.0 7.4 8.4

turbidity NTU – 2–15 27 68 39 2–200 62 10 2–200 50 623 248 136 536

total dissolved solids mg/L – – 1050 44000 358 – 463 17 – 305 1430 3060 592 904

total suspended solids mg/L – – 13 54 30 – 5 15 – 20 1530 172 31 15

electrical conductivity µS/cm – 20–250 854 68300 681 90–900 902 34 90–900 850 2080 5670 993 1540

Chemical Stressors

ammonia mg/L 0.01 – 0.05 0.01 0.040 0.036 0.045 0.01 0.023 0.013 0.01 0.028 0.100 0.070 0.080 0.060

oxides of nitrogen mg/L 0.01 – 0.05 0.005 0.02 0.02 0.03 0.005 0.01 0.02 0.001 0.03 0.01 0.02 0.01 0.01

Kjeldahl nitrogen mg/L 0.2 – 0.60 0.80 0.80 – 1.10 0.20 – 0.55 3.50 1.65 1.10 2.60

total nitrogen mg/L 0.2 0.3 0.60 0.90 0.80 0.35 1.10 0.20 1.2 0.55 3.50 1.65 1.10 2.60

total phosphorous mg/L 0.05 0.05 0.04 0.11 0.03 0.05 0.03 0.03 0.05 0.05 0.20 0.14 0.26 0.40

reactive phosphorous mg/L 0.001 – 0.05 0.004 0.013 0.025 0.025 0.005 0.015 0.025 0.025 0.025 0.090 0.025 0.030 0.250

total organic carbon mg/L 5 – 18 18 7 – 24 3 – 14 141 22 51 45

chlorophyll a µg/L 1 5 19.0 28.0 7.5 3 2.0 6.0 10 6.4 110.0 22.5 15.0 6.0

a As per table 2.1, s ites F15, F16, F19 and F20 were only sampled in June 2015, in the dry season, and values represent a single data point. Medians are presented for the remaining sites. Site F03 was sampled in June and August 2015. Sites F14 and

F18 were sampled 5 times. The remaining sites were sampled 4 times. DO and temperature were not sampled in January 2016 due to field constraints .

b Shaded cells contain values above the applicable AWQG trigger value. Values that are italicised are based on data where the LOR was higher than the applicable AWQG trigger on at least one occasion. In these calculations, where the LOR was less

than the trigger, the LOR was divided by 2.

frc environmental


Toxicants

Ammonia and Nitrate

The maximum concentrations of ammonia and nitrate were below the AWQG at all of the

sites that were sampled (Table 5.2).

Metals and Metalloids

The LORs for the total concentrations of metals and metalloids were above the AWQG for

mercury and silver in all surveys, and for cadmium, chromium, copper, lead, selenium,

and zinc in some analyses.

The maximum concentration of total metals and metalloids was above the AWQG for:

aluminium at each site

arsenic at sites F14, F15, F16, F19 and F20

boron at sites F14, F16 and F17

chromium at sites F14, F15, F16 (with LOR below AWQG for the maximum

concentration at sites F01, F02, F17 and F19)

copper at sites F14, F15, F16, F18 and F19 (with LOR below AWQG for the

maximum concentration at sites F01, F02, F03 and F20)

lead at sites F14, F15 and F17 (with the LOR below the AWQG at all other sites),

and

nickel at site F14 and F15 (Table 5.3).

The LORs for the dissolved concentrations of metals and metalloids were above the

AWQG for mercury and silver in all surveys, and for cadmium, chromium, copper,

selenium, lead and zinc in some analyses.

The maximum concentration of dissolved metals and metalloids was above the AWQG

for:

aluminium at site F17 (with the LOR below the AWQG at all other sites)

arsenic at sites F15, F16, F19 and F20, and

boron at sites F14 and F16 (Table 5.4).

frc environmental


Pesticides

There are no listed AWQG for pesticides; however, concentrations of pesticides were low

at each site in each survey, and below laboratory limits of reporting (Table 5.5 and Table

5.6).

Recoverable Hydrocarbons

The concentrations of recoverable hydrocarbons were below LOR at all sites, with the

exception of site F15. At site F15 the C15-C28 fraction of was above the LOR (Table 5.7).

Hydrocarbons in the C15-C28 range include diesels and lubricating oils. Site F15 is

adjacent to an access track. BTEXN were all below the LOR (Table 5.8).

Summary


low dissolved oxygen (i.e. lower than the AWQG), high turbidity and high nutrients in the

dry and pre-wet seasons. In Forsyth Creek Dam water quality was poorest in the pre-wet

season, with low dissolved oxygen and higher nutrients at this time. Water quality in the

ephemeral wetlands was poor to moderate, and characterised by low dissolved oxygen

and high turbidity, particularly in the remaining water in the dry season.

The maximum concentration of total and dissolved metals and metalloids, and in particular

aluminium, arsenic and boron, were sometimes above AWQG trigger levels, which require

further investigation. Other potential contaminants (hydrocarbons and pesticides) were all

below the AWQG, with the exception of C15-C28 hydrocarbons at site F15.

frc environmental


Table 5.2 The maximum concentration of ammonia and nitrate (mg/L) in the water at each site, and the AWQG trigger values for these parameters as toxicantsa.

Parameter LOR Range Lowland Rivers Reservoirs Wetlands


ammonia 0.01 – 0.05 0.9 0.070 0.130 0.110 0.9 <0.05 0.110 0.9 0.050 0.100 0.080 0.080 0.060

nitrate 0.002 – 0.02 0.7 0.01 0.01 0.01 0.7 0.01 0.01 0.7 – 0.01 0.04 0.01 0.01

a As per table 2.1, sites F15, F16, F19 and F20 were only sampled in June 2015, in the dry season, and values represent a single data point. Medians are presented for the remaining sites. Site F03 was

sampled in June and August 2015. Sites F14 and F18 were sampled 5 times. The remaining sites were sampled 4 times. DO and temperature were not sampled in January 2016 due to field constraints.

Table 5.3 The maximum concentration of total metals and metalloids (mg/L) in the water at each site, and the AWQG trigger valuesa.



aluminium 0.05 0.055 1.9 29.6 1.0 0.055 0.2 0.2 0.055 2.8 12.7 4.9 2.7 0.7

antimony 0.001 – 0.025 – <0.025 <0.025 <0.025 – <0.025 <0.025 – <0.025 <0.025 <0.025 <0.025 <0.025

arsenic 0.001 – 0.005 0.013 <0.005 0.018 <0.005 0.013 0.011 <0.005 0.013 0.008 0.039 0.036 0.025 0.022

boron 0.05 0.37 0.13 4.21 0.51 0.37 0.18 0.10 0.37 0.22 0.19 0.95 0.28 0.17

cadmium 0.0001 – 0.001 0.0002 <0.001 <0.001 <0.001 0.0002 <0.001 <0.001 0.0002 <0.001 <0.001 <0.001 <0.001 <0.001

chromium 0.001 – 0.005 0.001 <0.005 0.0490 <0.005 0.001 <0.005 <0.005 0.001 <0.005 0.0180 0.0070 <0.005 <0.005

copper 0.001 – 0.005 0.0014 <0.005 0.0270 <0.005 0.0014 <0.005 0.0060 0.0014 <0.005 0.0170 0.0110 0.0070 <0.005

iron – 2.2 36.7 1.7 – 0.2 0.7 – 2.3 15.4 4.7 3.0 0.9

lead 0.001 – 0.005 0.0034 <0.005 0.0120 0.0090 0.0034 <0.005 <0.005 0.0034 <0.005 0.0070 <0.005 <0.005 <0.005

manganese 0.005 1.9 0.06 0.73 0.19 1.9 0.01 0.04 1.9 0.01 0.68 0.09 0.12 0.23

mercury 0.0001 – 0.0005 0.00006 <0.0005 <0.0005 <0.0005 0.00006 <0.0005 <0.0005 0.00006 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005

molybdenum 0.001 – 0.025 – <0.025 <0.025 <0.025 – <0.025 <0.025 – <0.025 <0.025 <0.025 <0.025 <0.025

nickel 0.001 – 0.005 0.011 <0.005 0.027 <0.005 0.011 <0.005 <0.005 0.011 <0.005 0.014 <0.005 0.005 <0.005

selenium 0.001 – 0.1 0.005 <0.1 <0.1 <0.1 0.005 <0.1 <0.1 0.005 <0.1 <0.1 <0.1 <0.1 <0.1

silver 0.001 – 0.025 0.00005 <0.025 <0.025 <0.025 0.00005 <0.025 <0.025 0.00005 <0.025 <0.025 <0.025 <0.025 <0.025

uranium 0.001 – 0.025 – <0.025 <0.025 <0.025 – <0.025 <0.025 – <0.025 <0.025 <0.025 <0.025 <0.025

vanadium 0.01 – 0.1 – <0.1 <0.1 <0.1 – <0.1 <0.1 – <0.1 <0.1 0.1 <0.1 <0.1

zinc 0.005 – 0.05 0.008 <0.05 <0.05 <0.05 0.008 <0.05 <0.05 0.008 <0.05 <0.05 <0.05 <0.05 <0.05


sampled in June and August 2015. Sites F14 and F18 were sampled 5 times. The remaining sites were sampled 4 times. DO and temperature were not sampled in Jan uary 2016 due to field constraints.

frc environmental


Table 5.4 The maximum concentration of dissolved metals and metalloids (mg/L) in the water at each site, and the AWQG trigger valuesa.



aluminium 0.01 – 0.1 0.055 <0.1 <0.1 0.3 0.055 <0.1 <0.1 0.055 <0.1 <0.1 <0.1 <0.1 <0.1

antimony 0.001 – 0.025 – <0.025 <0.025 <0.025 – <0.025 <0.025 – <0.025 <0.025 <0.025 <0.025 <0.025

arsenic 0.001 – 0.01 0.013 <0.01 <0.01 <0.01 0.013 0.010 <0.01 0.013 <0.01 0.063 0.035 0.020 0.019

boron 0.05 0.37 0.13 4.45 0.17 0.37 0.16 <0.05 0.37 0.22 0.20 0.91 0.25 0.16

cadmium 0.0001 – 0.001 0.0002 <0.001 <0.001 <0.001 0.0002 <0.001 <0.001 0.0002 <0.001 <0.001 <0.001 <0.001 <0.001

chromium 0.001 – 0.01 0.001 <0.01 <0.01 <0.01 0.001 <0.01 <0.01 0.001 <0.01 <0.01 <0.01 <0.01 <0.01

cobalt 0.001 – 0.01 – – <0.01 <0.01 – <0.01 <0.01 – – <0.01 <0.01 <0.01 <0.01

copper 0.001 – 0.1 0.0014 <0.1 <0.1 <0.1 0.0014 <0.1 <0.1 0.0014 <0.1 <0.1 <0.1 <0.1 <0.1

iron 0.05 – 0.25 – <0.25 <0.25 <0.25 – – <0.25 – <0.25 – – – –

lead 0.001 – 0.01 0.0034 <0.01 <0.01 <0.01 0.0034 <0.01 <0.01 0.0034 <0.01 <0.01 <0.01 <0.01 <0.01

manganese 0.001 – 0.01 1.9 0.01 0.03 0.05 1.9 <0.01 0.06 1.9 <0.01 0.01 <0.01 <0.01 0.01

mercury 0.0001 – 0.0005 0.00006 <0.0005 <0.0005 <0.0005 0.00006 <0.0005 <0.0005 0.00006 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005

molybdenum 0.001 – 0.025 – <0.025 <0.025 <0.025 – <0.025 <0.025 – <0.025 <0.025 <0.025 <0.025 <0.025

nickel 0.001 – 0.01 0.011 <0.01 <0.01 <0.01 0.011 <0.01 <0.01 0.011 <0.01 <0.01 <0.01 <0.01 <0.01

selenium 0.001 – 0.1 0.005 <0.1 <0.1 <0.1 0.005 <0.1 <0.1 0.005 <0.1 <0.1 <0.1 <0.1 <0.1

silver 0.001 – 0.025 0.00005 <0.025 <0.025 <0.025 0.00005 <0.025 <0.025 0.00005 <0.025 <0.025 <0.025 <0.025 <0.025

uranium 0.001 – 0.025 – <0.025 <0.025 <0.025 – <0.025 <0.025 – <0.025 <0.025 <0.025 <0.025 <0.025

vanadium 0.005 – 0.1 – <0.1 <0.1 <0.1 – <0.1 <0.1 – <0.1 <0.1 <0.1 <0.1 <0.1

zinc 0.001 – 0.05 0.008 <0.05 <0.05 <0.05 0.008 <0.05 <0.05 0.008 <0.05 <0.05 <0.05 <0.05 <0.05


sampled in June and August 2015. Sites F14 and F18 were sampled 5 times. The remaining sites were sampled 4 times. DO and temperature were not sampled in January 2016 due to field constraints.

frc environmental


Table 5.5 The maximum concentration of organochlorine pesticides (µg/L) in the water at each sitea.


F01 F14 F17 F03 F18 F02 F15 F16 F19 F20

4.4`-DDD 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

4.4`-DDE 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

4.4`-DDT 0.1 – 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

aldrin 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

alpha-BHC 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

alpha-endosulfan 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

beta-BHC 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

beta-endosulfan 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

cis-chlordane 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

delta-BHC 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

dieldrin 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endosulfan sulfate 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endrin 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endrin aldehyde 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endrin ketone 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

gamma-BHC 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

heptachlor 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

heptachlor epoxide 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

hexachlorobenzene (HCB) 0.1 – 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

methoxychlor 0.1 – 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

sum of aldrin + dieldrin 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

sum of DDD + DDE + DDT 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

total chlordane (sum) 0.5 – 1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

toxaphene 10 <10 <10 <10 – <10 <10 – – – –

trans-chlordane 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

a As per table 2.1, sites F15, F16, F19 and F20 were only sampled in June 2015, in the dry season, and values represent a singl e data point. Medians are presented for the remaining

sites. Site F03 was sampled in June and August 2015. Sites F14 and F18 were sampled 5 times. The remaining sites were sampled 4 times. DO and temperature were not sampled

in January 2016 due to field constraints.

frc environmental


Table 5.6 The maximum concentration of organophosphorous pesticides (µg/L) in the water at each sitea.


F01 F14 F17 F03 F18 F02 F15 F16 F19 F20

azinphos methyl 0.5 – 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

bolstar 2 <2 <2 <2 – <2 <2 – – – –

bromophos-ethyl 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

carbophenothion 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

chlorfenvinphos 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

chlorpyrifos 0.5 – 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

chlorpyrifos-methyl 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

demeton-O 2 <2 <2 <2 – <2 <2 – – – –

demeton-S-methyl 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

diazinon 0.5 – 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

dichlorvos 0.5 – 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

dimethoate 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

disulfoton 2 <2 <2 <2 – <2 <2 – – – –

ethion 0.5 – 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

ethoprop 2 <2 <2 <2 – <2 <2 – – – –

fenamiphos 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

fenitrothion 2 <2 <2 <2 – <2 <2 – – – –

fensulfothion 2 <2 <2 <2 – <2 <2 – – – –

fenthion 0.5 – 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

malathion 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

merphos 2 <2 <2 <2 – <2 <2 – – – –

mevinphos 2 <2 <2 <2 – <2 <2 – – – –

naled 2 <2 <2 <2 – <2 <2 – – – –

phorate 2 <2 <2 <2 – <2 <2 – – – –

ronnel 2 <2 <2 <2 – <2 <2 – – – –

tokuthion 2 <2 <2 <2 – <2 <2 – – – –

monocrotophos 2 – <2 – <2 <2 – <2 <2 <2 <2

parathion 2 – <2 – <2 <2 – <2 <2 <2 <2

parathion-methyl 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

pirimphos-ethyl 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

prothiofos 0.5 – <0.5 – <0.5 <0.5 – <0.5 <0.5 <0.5 <0.5

trichloronate 2 <2 <2 <2 – <2 <2 – – – –

a As per table 2.1, sites F15, F16, F19 and F20 were only sampled in June 2015, in the dry season, and values represent a singl e data point. Medians are presented for the remaining

sites. Site F03 was sampled in June and August 2015. Sites F14 and F18 were sampled 5 times. The remaining sites were sampled 4 times. DO and temperature were not sampled

in January 2016 due to field constraints.

frc environmental


Table 5.7 The maximum concentration (µg/L) of recoverable hydrocarbons in the water

at each sitea.

Fraction LOR Lowland Rivers Reservoirs Wetlands

F01 F14 F17 F03 F18 F02 F15 F16 F19 F20

C6 - C9 20 <20 <20 <20 – <20 <20 – – – <20

C10 - C14 50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50

C15 - C28 100 <100 <100 <100 <100 <100 <100 260 <100 <100 <100

C29 - C36 100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100

a Sites F03, F15, F16, F19 and F20 were sampled in June 2015, sites F01, F02 and F17 were sampled

in March 2016 and sites F14 and F18 were sampled in both surveys for these parameters.

Table 5.8 The concentration of BTEXN (µg/L) in the watera.

Parameter LOR Lowland Rivers Reservoir Wetlands

F01 F14 F17 F18 F02 F20

benzene 1 – <1 <1 – – <1

toluene 2 – <2 <2 – – <2

ethylbenzene 2 – <2 <2 – – <2

meta- & para-xylene 2 – <2 <2 – – <2

ortho-xylene 2 – <2 <2 – – <2

total xylenes 2 – <2 <2 – – <2

sum of BTEX 1 – <1 <1 – – <1

naphthalene 10 <10 <10 <10 <10 <10 <10

a Site F20 was sampled in June 2015, sites F01, F02 and F18 were sampled in March 2016 and sites

F14 and F17 were sampled in both surveys for these parameters.

Phytoplankton

Phytoplankton communities were analysed in March 2016 and were dominated by

diatoms, with some cyanobacteria, flagellates and green algae (Table 5.9).

Cyanobacteria (non-toxic) and green algae were only recorded at the upstream reference

site (site F17) and in Forsyth Creek Dam (site F18), while flagellates were only recorded

in Forsyth Creek Dam. Diatoms were found at all sites and comprised several species

including:

frc environmental


Navicula spp.

Fragilariopsis sp.

Nitzschia sp.

Melosira granulata, and

Cylindrotheca closterium.

The highest concentration was 3600 cells/ml in Forsyth Creek Dam (site F18) and the

lowest was 180 cells/ml in Forsyth Creek at the site upstream of tidal influence (site F14).

These concentrations are similar to other water bodies from northern Australia, including

the Daly River where the concentration ranged between 30 and 205 cells/ ml (Townsend

et al. 2002); riverine conditions of the Mary River (126 to 129 cells/ml); and isolated lakes

in the flood plain channels of the Mary River system (1310 to 2590 cells/ml) (Townsend

2006).

Table 5.9 Phytoplankton communities (cells/mL) at each site in March 2016.

Lowland Rivers Reservoir Wetland

Species F01 F14 F17 F18 F02

Diatoms

Melosira granulate 1460 0 0 0 60

Navicula spp. 380 180 220 260 120

Nitzschia sp. 0 0 0 100 0

Fragilariopsis sp. 0 0 0 0 20

Cylindrotheca closterium 0 0 60 0 0

Cyanobacteria

Merismopedia punctate 0 0 40 0 0

Aphanocapsa holsatica 0 0 0 1060 0

Green Algae

Euglena sp. 0 0 20 0 0

Staurastrum spp. 0 0 0 1260 0

Cosmarium sp. 0 0 0 80 0

Schroederia sp. 0 0 0 180 0

Monoraphidium sp. 0 0 0 620 0

Flagellates

Trachelomonas sp. 0 0 0 20 0

Gymnodinium sp. 0 0 0 20 0

frc environmental


6 Sediment Quality

In previous studies the concentration of metals and metalloids in sediment were below

Sediment Quality Guideline (SQG) trigger values in the freshwater and upper estuarine

reaches of the Keep River, with the exception of mercury and nickel (WRM 2014).

However, there were no consistent trends in the concentration of mercury and nickel. The

concentration of several metals were higher in the freshwater waterways than in the

estuarine waterways, including (WRM 2014):

aluminium

barium

bismuth

cobalt

copper

chromium

iron

gallium

nickel

lead

selenium

uranium, and

vanadium.

In the Keep River the concentration of total nitrogen and ammonium decreased with

distance downstream, with concentrations as high as 1 030 mg/kg at a site near the

Legune Road crossing (WRM 2014). While there were large variations in the

concentration of total phosphorus between both sites and years, it was typically lower in

freshwater sites than in estuarine sites (WRM 2014).

frc environmental


6.1 Sediment Composition and Quality of Water Bodies on Legune

Station

Sediment Composition

Sediment was predominantly fine, including silt / clay with some sand, with the exception

of the upstream Alligator Creek site (site F17) and Forsyth Creek Dam (site F18) that were

dominated by sand with some silt / clay and gravel (Table 6.1). Fine sediments are more

susceptible to being resuspended and transported downstream than coarser sediments,

and are more likely to accumulate contaminants through adsorption due to a high surface

area (Simpson et al. 2005).

In March 2016, when three sediment samples were analysed per site, there was little

difference between samples (Table 6.2).

Metals and Metalloids

The concentration of most metals and metalloids were below the SQG trigger values

(Table 6.1 and Table 6.2). Exceptions were:

lead at site F14 in June 2015

lead at the upstream site in Alligator Creek (site F17) in June 2015 which was also

above the SQG-high trigger value

lead at site F17 in March 2016, and

arsenic at site F17 in March 2016.

In March 2016 the LOR for silver was 5 mg/kg, above both the SQG trigger value

(1 mg/kg) and the SQG-high trigger value (4). It is considered unlikely that silver

exceeded the SQG-high trigger value at this time, as in both previous surveys it was

<0.1mg/kg.

In March 2016 the LOR for antimony was 10 mg/kg, above the SQG trigger value (2

mg/kg) but below the SQG-high trigger value (25). It is considered unlikely that antimony

exceeded the SQG trigger value at this time, as in both previous surveys it was

<0.5mg/kg.

frc environmental


Nutrients

The concentrations of nutrients varied between sites and between surveys (Table 6.1 and

Table 6.2).

Pesticides

The concentrations of all organochlorine and organophosphorous pesticides were below

laboratory limits of reporting in each survey and below SQG trigger values (Table 6.1).

Recoverable Hydrocarbons

The concentrations of recoverable hydrocarbons was below the SLOR at each site in

each survey (Table 6.1 and Table 6.2), and the total concentrations of hydrocarbons at

were below the SQG triggers.

frc environmental


Table 6.1 Sediment quality at each site in June and October 2015 compared to the sediment quality guidelines.

Parameter Units SQG Trigger

Value

SQG High

Value

Jun-15 Jun-15 Jun-15 Jun-15 Jun-15 Jun-15 Jun-15 Jun-15 Oct-15 Oct-15 Oct-15 Oct-15

F03 F14 F15 F16 F17 F18 F19 F20 F01 F14 F17 F18

Particle Size

<63 µm (clay & silt) % – – 95 99 100 98 24 50 94 93 0.5 25 79 10

63–125 µm (very fine sand) % – – <1 <1 <1 <1 3 9 <1 1 2 3 8 17

125–250 µm (fine sand) % – – 1 1 <1 1 11 3 1 1 1 2 7 10

250–500 µm (medium sand) % – – <1 <1 <1 <1 30 <1 <1 1 1 2 1 <1

500–1000 µm (coarse sand) % – – 1 <1 <1 <1 9 <1 2 2 2.5 2 1 <1

1000–2000 µm (very coarse sand) % – – 2 <1 <1 <1 7 <1 1 2 5 3 1 2

>2000 µm (gravel & cobbles) % – – 1 <0.1 <0.1 <0.1 16 38 2 <0.1 88 64 3 61

Total Metals and Metalloids

aluminium mg/kg – – 23100 16600 22600 22650 7060 5080 28500 26000 – – – –

antimony mg/kg 2 25 <0.5 <0.5 <0.5 <0.5 1 <0.5 <0.5 <0.5 – – – –

arsenic mg/kg 20 70 5 5 4 3 12 2 7 3 – – – –

boron mg/kg – – 13 24 11 24 <5 <5 18 15 – – – –

cadmium mg/kg 1.5 10 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 – – – –

chromium mg/kg 80 370 27 23 26 26 33 12 34 31 – – – –

copper mg/kg 65 270 14 21 14 14 11 5 16 18 – – – –

iron mg/kg – – 27200 28300 26500 24600 43300 20200 35300 30400 – – – –

lead mg/kg 50 220 9 75 8 9 281 7 11 10 – – – –

manganese mg/kg – – 292 229 216 412 706 82 408 274 – – – –

mercury mg/kg 0.15 1 <0.01 <0.01 <0.01 <0.01 <0.01 0.01 <0.01 <0.01 – – – –

molybdenum mg/kg – – <0.1 0.5 <0.1 <0.1 1.2 0.5 0.1 0.1 – – – –

nickel mg/kg 21 52 13 17 13 12 7 1 16 15 – – – –

selenium mg/kg – – 0.4 0.3 0.3 0.3 0.3 0.3 0.4 0.4 – – – –

silver mg/kg 1 4 <0.1 <0.1 0.1 <0.1 <0.1 <0.1 <0.1 <0.1 – – – –

uranium mg/kg – – 0.3 0.7 0.2 1.4 0.6 0.4 0.6 0.3 – – – –

vanadium mg/kg – – 44 31 45 38 54 19 50 46 – – – –

zinc mg/kg 200 410 25 52 25 24 36 4 31 31 – – – –

Nutrients

ammonia (as N) mg/kg – – 40 <20 30 <20 20 <20 20 30 27 <20 46 <20

nitrate (as N) mg/kg – – <0.1 <0.1 0.7 0.2 0.6 0.7 <0.1 0.2 0.9 0.4 0.3 0.6

nitrite (as N) mg/kg – – <0.1 <0.1 <0.1 1.1 <0.1 <0.1 <0.1 0.2 6.4 0.3 0.3 <0.1

nitrite + nitrate (as N) mg/kg – – <0.1 <0.1 0.7 1.2 0.6 0.7 <0.1 0.4 – – – –

organic nitrogen (as N) mg/kg – – – – – – – – – – 740 405 1200 1500

total Kjeldahl nitrogen (as N) mg/kg – – 560 1400 1650 1125 140 380 610 3840 765 410 1200 1500

total nitrogen (as N) mg/kg – – 560 1400 1650 1125 140 380 610 3840 775 410 1200 1500

frc environmental



Value

SQG High

Value


F03 F14 F15 F16 F17 F18 F19 F20 F01 F14 F17 F18

total phosphorus as P mg/kg – – 204 247 294 180 64 156 267 401 – – – –

reactive phosphorus as P mg/kg – – 1 0 1 6 1 <0.1 0 2 – – – –

total organic carbon % – – 0.63 1.03 0.92 0.48 0.39 0.15 0.81 3.54 0.6 0.5 1.5 0.7

Total Recoverable Hydrocarbons

TRH C6-C10 mg/kg – – <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20

TRH >C10-C16 mg/kg – – <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50

TRH >C16-C34 mg/kg – – <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100

TRH >C34-C40 mg/kg – – <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100

TRH >C10 - C40 Fraction (sum) mg/kg – – 57 37 118 18 41 5 13 88 <20 <20 <20 <20

Organochlorine Pesticides

4.4'-DDD µg/kg 3.5 9 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

4.4'-DDE µg/kg 1.4 7 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

4.4'-DDT µg/kg 1.2 5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

a-BHC µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Aldrin µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

b-BHC µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

cis-Chlordane µg/kg – – <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 – – – –

trans-Chlordane µg/kg – – <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 – – – –

chlordanes - Total µg/kg 4.5 9 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25

d-BHC µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

dieldrin µg/kg 2.8 7 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endosulfan I µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endosulfan II µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endosulfan sulphate µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endrin µg/kg 2.7 60 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endrin aldehyde µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

endrin ketone µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

g-BHC (Lindane) µg/kg 0.9 1.4 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25

heptachlor µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

heptachlor epoxide µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

hexachlorobenzene µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

methoxychlor µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

oxychlordane µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 – – – –

toxaphene µg/kg – – – – – – – – – – <1 <1 <1 <1

Organophosphorous Pesticides

azinphos Methyl µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

frc environmental



Value

SQG High

Value


F03 F14 F15 F16 F17 F18 F19 F20 F01 F14 F17 F18

bolstar µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

bromophos-ethyl µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

carbophenothion µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

chlorfenvinphos (E) µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

chlorfenvinphos (Z) µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

chlorpyrifos µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

chlorpyrifos-methyl µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

demeton-O µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

demeton-S-methyl µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

diazinon µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

dichlorvos µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

dimethoate µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

disulfoton µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

ethion µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

ethoprop µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

fenitrothion µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

fenamiphos µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

fensulfothion µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

fenthion µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

malathion µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

merphos µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

methyl azinphos µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

methyl parathion µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

mevinphos µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

monocrotophos µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

naled µg/kg – – – – – – – – – – <0.5 <0.5 <0.5 <0.5

parathion µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

parathion-methyl µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

phorate µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

pirimphos-ethyl µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

ronnel µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

prothiofos µg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 – – – –

tokuthion µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

trichloronate µg/kg – – – – – – – – – – <0.2 <0.2 <0.2 <0.2

light shading indicates concentrations above sediment quality guideline trigger values

dark shading indicates concentrations above sediment quality guideline high trigger values

– not surveyed

frc environmental


Table 6.2 Sediment quality at each site in March 2016 compared to the sediment quality guidelines.

Parameter Units

SQG

Trigger

Value

SQG

High

Value

F01

F02

F14

F17

F18

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

Particle Size

<63 µm (clay & silt) % – – 0.5 1.2 10 86 81 84 38 17 26 3.9 5.6 0.4 8.5 5.7 16

63–125 µm (very fine sand) % – – 1.3 4.9 1.3 4.6 8.7 6.1 11 8.5 8.4 4.1 4.2 3.9 5.6 7.2 4.8

125–250 µm (fine sand) % – – 1 1.7 1.6 3.2 4.3 2.2 20 19 14 8.4 9.3 23 4.8 2.9 2.4

250–500 µm (medium sand) % – – 1.1 1 1.7 0.9 2.2 2.1 4.1 4 4.9 5.1 8.6 18 3.1 1.6 1.7

500–1000 µm (coarse sand) % – – 4.5 2.4 4.5 1.4 1.9 2.4 4.7 4.1 4.4 5.4 8.5 8.2 6.6 7.9 6.7

1000–2000 µm (very coarse

sand)

% – – 11 5 8 2 1.3 1.8 4.3 3.8 3.6 6 8.3 4.4 12 18 14

>2000 µm (gravel & cobbles) % – – 81 84 73 2.4 0.7 2 19 44 39 67 56 43 59 56 54

Total Metals and Metalloids

aluminium mg/kg – – 18000 11000 7900 24000 21000 23000 7000 7800 5600 7600 7900 5000 5900 8100 5800

antimony mg/kg 22 25 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

arsenic mg/kg 20 70 8.5 9.6 9.9 8.6 6.9 10 7.5 4 11 26 26 16 7.6 13 6.8

boron mg/kg – – <10 <10 <10 11 11 14 <10 <10 <10 <10 <10 <10 <10 <10 <10

cadmium mg/kg 1.5 10 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4

chromium mg/kg 80 370 16 18 21 26 25 26 13 13 8.8 46 60 25 9.7 19 11

copper mg/kg 65 270 18 17 16 13 13 13 13 10 8.7 18 13 9.7 16 18 17

iron mg/kg – – 27000 29000 36000 32000 26000 29000 29000 27000 19000 54000 54000 32000 17000 38000 18000

lead mg/kg 50 220 11 21 11 <5 <5 5.4 21 10 9.4 120 130 130 12 14 10

manganese mg/kg – – 480 720 590 220 190 210 720 250 610 1100 1100 690 100 100 100

mercury mg/kg 0.15 1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

molybdenum mg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

nickel mg/kg 21 52 10 11 8.8 9 9.7 9.6 7.6 8 6.5 8.1 8.7 6.8 10 10 11

selenium mg/kg – – <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

silver mg/kg 12 4 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5

uranium mg/kg – – 79 87 95 91 82 90 76 73 59 150 150 91 45 64 54

vanadium mg/kg – – 14 21 16 45 37 38 18 15 14 62 65 36 <10 13 10

zinc mg/kg 200 410 36 30 27 18 17 17 13 13 14 48 63 33 27 31 33

Nutrients

ammonia (as N) mg/kg – – <5 <5 <5 21 19 42 <5 <5 <5 12 6.3 5.6 <5 <5 <5

nitrite + nitrate (as N) mg/kg – – <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5

total Kjeldahl nitrogen (as N) mg/kg – – 120 220 100 1200 2000 2500 130 160 230 420 320 140 120 95 83

total nitrogen (as N) mg/kg – – 120 220 100 1200 2000 2500 130 160 230 420 320 140 120 95 83

total phosphorus as P mg/kg – – <100 <100 <100 220 220 250 <100 <100 <100 190 160 <100 <100 <100 <100

2 The laboratory limit of reporting was higher than the SQG trigger value.

frc environmental


Parameter Units

SQG

Trigger

Value

SQG

High

Value

F01

F02

F14

F17

F18

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

reactive phosphorus as P mg/kg – – <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Total Recoverable Hydrocarbons

TRH C6-C10 mg/kg – – <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20

TRH >C10-C16 mg/kg – – <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50

TRH >C16-C34 mg/kg – – <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100

TRH >C34-C40 mg/kg – – <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100

TRH >C10 - C40 Fraction

(sum)

mg/kg – – <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100 <100

Organochlorine Pesticides

4.4'-DDD µg/kg 3.5 9 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

4.4'-DDE µg/kg 1.4 7 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

4.4'-DDT µg/kg 1.2 5 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

a-BHC µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

Aldrin µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

b-BHC µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

chlordanes - total µg/kg 4.5 9 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

d-BHC µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

dieldrin µg/kg 2.8 7 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

endosulfan I µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

endosulfan II µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

endosulfan sulphate µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

endrin µg/kg 2.7 60 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

endrin aldehyde µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

endrin ketone µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

g-BHC (Lindane) µg/kg 0.9 1.4 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

heptachlor µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

heptachlor epoxide µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

hexachlorobenzene µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

methoxychlor µg/kg – – <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

toxaphene µg/kg – – <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Organophosphorous Pesticides

bolstar µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

chlorpyrifos µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

demeton-O µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

demeton-S-methyl µg/kg – – – – – – – – – – – – – – – – –

diazinon µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

frc environmental


Parameter Units

SQG

Trigger

Value

SQG

High

Value

F01

F02

F14

F17

F18

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

dichlorvos µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

disulfoton µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

ethion µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

ethoprop µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

fenitrothion µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

fensulfothion µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

fenthion µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

merphos µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

methyl azinphos µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

methyl parathion µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

mevinphos µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

naled µg/kg – – <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

phorate µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

ronnel µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

tokuthion µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

trichloronate µg/kg – – <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

light shading indicates concentrations above sediment quality guideline trigger values

dark shading indicates concentrations above sediment quality guideline high trigger values

– not surveyed

frc environmental


7 Aquatic Flora and Fauna

7.1 Aquatic flora

Plant communities associated with water bodies in northern Australia are diverse,

reflecting the diverse environments in which they occur. Community structure and

species distribution are strongly related to distinct differences between wet and dry

seasons. Aquatic plants are found in most wetland habitats in northern Australia,

including streams, rivers, waterholes and inundated floodplains. The greatest diversity of

aquatic plants is usually found in and around large perennial flood plain water holes, with

diversity along rivers relatively low. Aquatic plants in northern Australia are typically

adapted to growing quickly and reproducing in the wet season. Seeds and tubers

frequently lie dormant in the dry season, with germination and growth in the wet season

(Pettit et al. 2011).

Aquatic vegetation in the Victoria River catchment was surveyed between 1995 and 1999

as part of the Top End Waterways Project (Kirby & Faulks 2004). The most common

species were Melaleuca leucadendra and Pandanus aquaticus (Table 7.1). No exotic

aquatic plants were recorded in the Victoria River catchment in this survey (Kirby & Faulks

2004).

Table 7.1 Aquatic plant species of the Victoria River catchment a.

Species Name Growth Form Percent of Sites Recorded

Melaleuca leucadendra emergent 21

Pandanus aquaticus emergent 18

Chara sp. submerged 14

Eriachne festucacea emergent 6

Myriophyllum verrucosum submerged 4

Cyperus victoriensis emergent 3

Cyperus vaginatus emergent 3

Melaleuca argentea emergent 3

Nymphaea violacea free-floating attached 3

Cynodon dactylon emergent 3

Phragmites karka emergent 3

Muehlenbeck ia florulenta emergent 3 a excluding mangroves

frc environmental


Aquatic Flora Recorded on the Site

Approximately 13 species of aquatic plants were recorded along the waterways of Legune

Station, including:

water snowflake (Nymphoides indica) (Figure 7.1)

waterlily (Nymphaea violacea)

common joyweed (Alternanthera nodiflora)

spikerush (Eleocharis spp.)

clubrush (Schoenoplectus spp.) (Figure 7.2)

elodea (Elodea canadensis)

ribbonweed (Vallisneria nana)

sedge (Cyperus spp.)

chara (Chara sp.)

azolla (Azolla pinnata) (Figure 7.3)

pond weed (Potamogeton octandrus) (Figure 7.4)

cumbungi (Typha sp.), and

water primrose (Ludwigia perennis).

All species recorded are commonly occurring aquatic plants, many of which are typical of

disturbed ecosystems (e.g. cumbungi and azolla).

No listed threatened or declared pest aquatic plant species were recorded in the surveys.

In general, aquatic plant communities were denser at sites that held more permanent,

water, such as Forsyth Creek Dam.

frc environmental


Figure 7.1

Water snowflake.

Figure 7.2

Clubrush.

Figure 7.3

Azolla.

frc environmental


7.2 Macroinvertebrate Communities

Aquatic macroinvertebrates have a fundamental ecological role in freshwater systems of

northern Australia, being a part of the food web as primary consumers and prey for

secondary consumers (Pusey 2011). Aquatic macroinvertebrates break down organic

detritus, filter feed and graze on algae, provide food for other fauna (e.g. birds and fish)

and underpin recreational fisheries (e.g. the barramundi fishery) (Pusey 2011).

In previous surveys, a total of 345 macroinvertebrate taxa were recorded from sites and

habitats sampled in the Keep River catchment (WRM 2014). Sites comprised isolated

pools in the lower Keep River and reference sites in the surrounding catchment, such as

Milligan’s Lagoon, Alligator Waterhole, Dunham River, Augustus Waterhole and

Policeman’s Waterhole. Insects, predominantly fly larvae (order Diptera), and aquatic

beetles (order Coleoptera) comprised 87% of taxa collected, while other species-rich

faunal groups included true bugs (order Hemiptera), mayflies (order Ephemeroptera),

caddisflies (order Trichoptera) and dragonflies / damselflies (order Odonata) (WRM 2014).

The majority of macroinvertebrates collected were common, ubiquitous species, with

distributions extending throughout Australia, and no species listed as rare or endangered

under State or Commonwealth legislation were recorded.

The highly seasonal rainfall and hence stream flow of northern Australia has major

implications for aquatic invertebrate communities. Typically, invertebrate abundance in

stream channels decreases rapidly with wet season flows, with richness and abundance

increasing once flooding ceases. However, in lower reaches, abundance may increase

with floods as invertebrates are washed down from dry season refuges (Garcia et al.

2011).

Figure 7.4

Pond weed.

frc environmental


Macroinvertebrate Community Composition and Diversity in Water Bodies

on Legune Station

Community Composition

The water bodies that were sampled were moderately disturbed due to vegetation clearing

and cattle grazing. These activities are likely to have resulted in a decrease in cover and

habitat diversity, and led to increased nutrient inputs into the waterways, particularly

during periods of flow. These factors are likely to have influenced aquatic

macroinvertebrate communities.

The freshwater macroinvertebrate communities at each site were dominated by taxa

common to moderately disturbed ecosystems. Common taxa were:

aquatic beetles (families Dytiscidae and Hydrophilidae)

mayflies (families Baetidae and Caenidae)

non-biting midge larvae (sub-families Chironominae and Tanypodinae)

freshwater snails (families Hydrobiidae and Planorbidae), and

water boatmen (family Corixidae).

Aquatic beetles, freshwater snails and water boatmen, are common in slow moving or still

waters (Gooderham & Tsyrlin 2002), which are characteristic of the waterways around

Legune Station (Section 4).

The macroinvertebrate communities were significantly different between March 2016, and

June 2015 and October 2015 (ANOSIM, p = 0.001, R = 0.299) (Figure 7.5). These

differences were mostly due to higher abundances of water boatmen (family Corixidae)

and non-biting midge larvae (sub-family Chironominae) in June and October 2015 than in

March 2016 (SIMPER analysis). These two species are commonly found in slow-moving

or still waters and are a good food source for fish (Gooderham & Tsyrlin 2002). There

were no correlations between macroinvertebrate communities and water quality (BEST,

Rho = 0.372, p = 0.366), indicating differences between communities and times, were

more likely to be a result of differences in habitat and flows, with higher flows and more

area inundated in the March 2016 survey, following the wet season.

While the macroinvertebrate communities were similar at all of the sites, there were:

more diving beetles (family Dytiscidae) per sample in wetlands than in reservoirs

or creeks, and

frc environmental


more non-biting midge larvae (sub-family Chironominae) and water boatmen

(family Corixidae) per sample in reservoirs than in wetlands or creeks.

Figure 7.5 Non-metric multi-dimensional scaling plot of freshwater macroinvertebrate

communities at each site in each survey.

SurveyJun-15

Oct-15

Mar-16

2D Stress: 0.16

frc environmental


Mean Abundance

The abundance of freshwater macroinvertebrates is commonly higher in the dry season

when less habitat is available and flow is lower, although there is a greater area for

macroinvertebrates to colonise in the wet season. Strong flows in the wet season can

wash fauna downstream (Pusey 2011).

The mean abundance of macroinvertebrates was lowest in the post wet season (March

2016) at the lowland river sites (e.g. sites F01, F14 and F17). At Forsyth Creek Dam (site

F18), the mean abundance per sample was similar in the dry and post wet seasons (June

2015 and March 2016), and much higher in October 2015, when water level was low. Site

F02 was sampled in in the dry and post wet season, and abundance per sample was

similar (Figure 7.6).

Figure 7.6 Mean abundance of freshwater macroinvertebrates at each site in each

survey.

x – x x x x x x x x x 0

50

100

150

200

250

300

350

400

450

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Mean

Ab

un

dan

ce

(± S

E)

Jun-15

Oct-15

Mar-16

– dry site

x not surveyed

frc environmental


Mean Taxonomic Richness

Taxonomic richness commonly decreases in the wet season and increases in the dry

season when flows return to baseline conditions (Pusey 2011).

In the lowland river sites taxonomic richness was lowest in the post wet season at site F01

in Alligator Creek and site F14 in Forsyth Creek, but was similar in all surveys at site F17,

upstream in Alligator Creek. In contrast, taxonomic richness was highest in the pre-wet

season (October 2015) in Forsyth Creek Dam (Figure 7.7).

Figure 7.7 Mean taxonomic richness of freshwater macroinvertebrates at each site in

each survey.


2

4

6

8

10

12

14

16

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Mea

n T

axo

no

mic

Ric

hn

ess

(± S

E)

Jun-15

Oct-15

Mar-16

– dry site

x not surveyed

frc environmental


Mean PET Richness

The mean PET richness was relatively low (<3) at each site in each survey. As

Plecoptera are not tropical species, PET richness scores are likely to be relatively l ow in

the region (Gooderham & Tsyrlin 2002). There were no PET taxa at site F02 (an

ephemeral wetland) in either survey; at site F14 in October 2015; or, at sites F16 and F19

in June 2015 (Figure 7.8). Mayflies dominated PET taxa; however, there were some

caddisfly larvae at some sites (e.g. two net spinning caddis (family Hydropsychidae) at the

upstream Alligator Creek site (site F17) in June 2015). Net spinning caddis are commonly

more abundant in base flow conditions of the dry season (Pusey 2011).

Figure 7.8 Mean PET richness of freshwater macroinvertebrates at each site in each

survey.


0.5

1

1.5

2

2.5

3

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Mean

PE

T R

ich

ness

(± S

E)

Jun-15

Oct-15

Mar-16

– dry site

x not surveyed

frc environmental


Mean SIGNAL 2 Scores

Mean SIGNAL 2 scores were relatively low (<4) (Figure 7.9), which is likely to be due to

the harsh physical environment and ephemeral nature of the water bodies, the

disturbance by cattle, and the dominance of finer substrates (i.e. silts and clays) that are

common to the water bodies of Legune Station.

Figure 7.9 Mean SIGNAL 2 scores at each site in each survey.

Summary

The abundance and diversity of freshwater macroinvertebrate communities on Legune

Station were relatively low, and typical of disturbed ephemeral waterbodies with relatively

fine sediment. There is little structure, such as in-stream or riparian vegetation, to provide

varied habitat for macroinvertebrates. The relatively poor water quality (and in particular

low dissolved oxygen) is also likely to limit these communities. Grazing of the area by

cattle is likely to have negatively impacted these communities by reducing cover, and

decreasing water quality.


0.5

1

1.5

2

2.5

3

3.5

4

4.5

F01 Alligator Ck

F14 Forsyth Ck



F18 Forsyth Ck Dam

F02 Ephemeral

wetland

F15 Unnamed wetland

F16 Osman's Lake

F19 Unnamed wetland

F20 Unnamed wetland


Me

an

SIG

NA

L 2

Sc

ore

(± S

E)

Jun-15

Oct-15

Mar-16

– dry site

x not surveyed

frc environmental


While the communities were similar in each of the different types of water bodies, there

were more diving beetles in the wetlands, and more non-biting midge larvae and water

boatmen in the reservoirs.

In the lowland river sites the abundance of macroinvertebrates was lowest in the wet

season, and taxonomic richness lowest in the post-wet season. At Forsyth Creek Dam

abundance and taxonomic richness were highest in the pre-wet season, when water

levels were low. This pattern is typical of water bodies in northern Australia, with

abundance and richness decreasing with higher flows.

7.3 Fish

In northern Australia, rivers, flood plains and billabongs support a high diversity of

freshwater animals (Finlayson et al. 1988), including many species of fish (Bishop &

Forbes 1991; Bishop 1995). Six species of elasmobranchs and 176 species of bony fish

have been recorded from freshwater systems in Northern Australia (Pusey 2011).

In general, fish of northern Australia typically require access to estuarine and marine

waters at some point during their life history, typically for reproduction (Pusey 2011).

Movement and migration are key components of the biology and ecology of northern fish

as species move around to access food sources, for reproduction and to access refugial

habitats in the dry season (Pusey 2011). These fish often rely on a variety of

interconnected habitats, depending on the season. For example, the largetooth sawfish,

Pristis pristis formerly Pristis microdon, spends considerable time in freshwater, moving

upstream in the dry season and downstream in the wet season (Thorburn et al. 2004;

Peverell 2009).

While many species breed continuously throughout the year, others are seasonal

spawners with breeding coinciding with the onset of the wet season. Species that breed

during the wet season take advantage of extensive flooding that generally causes

increases in:

plankton and macroinvertebrates (i.e. food availability)

the distribution and density of aquatic plant communities

the area and diversity of aquatic habitats available, and

available protection from predation.

Many species that breed during the wet season move upstream or across inundated

floodplains to spawn, and newly hatched young often remain either upstream or in

frc environmental


floodplain pools. In floodplain pools, fish may perish if the pools dry over the subsequent

dry season, often falling prey to birds as water levels decline. Juvenile fish that inhabit

inundated floodplains during the wet season, and permanent floodplain pools during the

dry season, are an important food source for large predatory fish species, such as

barramundi. Nonetheless, several species also spawn in isolated waterholes when there

is no flow, and typically show strong patterns of juvenile recruitment following extensive

inundation of the floodplain (Arthington et al. 2005; Balcombe & Arthington 2009).

Fishes in the seasonal tropics tend to reproduce at a small size and early age (Low-

McConnell 1975). Most species mature after one or two years, enabling spawning in the

subsequent wet season; thus, there is a high turnover of local populations. Inter-seasonal

(or inter-annual) variability in populations is largely attributed to factors that influence

breeding success, such as the extent of flooding, physical and chemical conditions, and

biotic factors (McConnell & Lowe-McConnell 1987). However, population variability is

also influenced by the seasonal variation in habitat availability with movement onto newly

inundated floodplains in the wet season and movement into refugial waterholes in the dry

season (Pusey 2011).

Relatively small species, such as those from the families Atherinidae, Ambassidae,

Gobiidae, Eleotrididae and Melanotaeniidae, are generally carnivorous or omnivorous.

The atherinids and ambassids frequently feed on microcrustaceans from the middle of the

water column, while eleotrids and gobiids are bottom feeders. There are relatively few

primarily piscivorous fish species, such as barramundi, in the freshwaters of the region.

Regionally, approximately 90 species of fish have been recorded in the freshwater

reaches of the Keep, Victoria and Ord River catchments, with approximately 70 in riverine

pools in the Keep River catchment (Larson 1999; WRM 2014) (Table 7.2).

In an earlier survey of billabongs and rocky escarpments of the upper Keep River and

Sandy Creek region, to the south of Legune Station, 32 species of estuarine and

freshwater fish were recorded (Larson 1999).

The most common and abundant species are bony bream (Nematalosa erebi), diamond

mullet (Liza alata) and blue catfish (Neoarius graeffei) (WRM 2014). Other widespread

but less abundant species are the seven-spot archerfish (Toxotes chatareus), barramundi

(Lates calcarifer) and common ponyfish (Leiognathus equulus).

Most species recorded in these rivers systems (Table 7.2) may periodically occur on

Legune Station. However, the characteristic lack of dense vegetation and high turbidity of

the water bodies on the station limits the distribution of some of these species. For

example, exquisite and black banded rainbow fish (M. exquisita and M. nigrans) are

usually found in clear, upland waterbodies (Allen 1989), while species such as mouth

frc environmental


almighty (Glossamia aprion) are most commonly associated with water bodies with dense

vegetation.

Other species recorded in these catchments are marine vagrants: fish that are primarily

estuarine or marine that irregularly move into freshwater. Marine vagrants include

species, such as mangrove jack (Lutjanus argentimaculatus), common ponyfish

(Leiognathus equulus), sea mullet (Mugil cephalus), gudgeons and gobies. Freshwater

habitats on Legune Station may be seasonally available to them, and provide seasonal

sources of prey.

Movement is a key feature of many of the fish recorded in the region, with most species

moving (Pusey et al. 2011):

to access newly created food sources such as intermittent streams and

floodplains, species include species regularly found in freshwater and marine

vagrants and/or

for reproduction with:

potamodromous fish migrating within freshwater reaches for breeding e.g.

plotosid catfish (Neosilurus hyrtilli and H. ater ) and black bream (Hephaestus

fuliginosus)

catadromous fish migrating down rivers to the sea to spawn (e.g. barramundi

(Lates calcifer), diamond mullet (Liza alata), Indian short finned eel (Anguilla

bicolor) and Oxeye herring (Megalops cyprinoides)), and

anadromous species migrating up rivers from the sea to spawn and/ or

to access refugial habitats in the dry season.

The fish communities in the water bodies on Legune Station are likely to have been

impacted both by the installation of roads, bunds and artificial dams that prohibit fish

passage (e.g. man-made road at site F01) and by clearing and cattle grazing. The

removal of trailing roots, overhanging vegetation, shading of the waterways and the lack

of large woody debris (i.e. from natural occurrences of trees and branches falling into the

waterways) has reduced habitat availability. Cattle on the property also contribute to

poorer water quality through the input of excess nutrients and disturbing the in-stream bed

sediments.

Never-the-less, there are likely to be diverse fish communities in the water bodies on the

station, and water bodies such as Forsyth Dam and Osman’s Lagoon are likely to provide

refugial habitat in the dry season for a variety of species. The persistence of refugial

water bodies determines whether isolated fauna are able to recolonise once flow

resumes.

frc environmental


Table 7.2 Fish species recorded in the Keep, Ord and Victoria Rivers.

Family Species Common Name Catchment

Keep River Ord River Victoria River

Apogonidae Glossamia aprion mouth almighty x x x

Anguillidae Anguilla b icolor Indian short–finned eel x

Ambassidae Ambassis agrammus sailfin glassfish x

Ambassis interuptus long–spined glassfish x x

Ambassis macleayi Macleay's glassfish x x x

Ambassis sp.3 (muelleri) glassfish x x

Ambassis sp. glassfish x x x

Parambassis gulliveri giant glassfish x x

Ariidae Arius dioctes – x

Arius graeffei lesser salmon catfish, blue catfish x x x

Arius midgeleyi silver cobbler, shovel–nosed catfish x x x

Arius sp. fork–tailed catfish x x

Neoarius leptaspis triangular shield catfish, salmon catfish x x x

Plicofollis argyropleuron long–snouted catfish x

Atherinidae Craterocephalus stercusmuscarum fly–specked hardyhead x x x

Craterocephalus stramineus strawman, blackmast x x

Craterocephalus sp. hardyhead x

Belonidae Strongylura krefftii freshwater longtom x x x

Carangidae Scomberoides commersonianus giant queenfish x

Carcharhinidae Carcharhinus leucas bull shark x x

Clupeidae Nematalosa erebi bony bream x x x

Nematalosa vlaminghi Perth herring x

Dasyatidae Himantura dalyensis freshwater whipray x x

Eleotridae Hypseleotris compressa empire gudgeon x x

Hypseleotris sp. golden gudgeon x

Mogurnda mogurnda northern trout gudgeon x x

Oxyeleotris lineolatus sleepy cod x

Oxyeleotris selheimi giant gudgeon x x x

Oxyeleotris sp. gudgeon x

Elopidae Elops australis herring x

Elops hawaiensis giant herring x

Elops machnata Australian giant herring x

Engraulidae Thryssa brevicauda short-tail thryssa x

frc environmental




Thryssa kammalensis kammal thryssa x

Thryssa sp. anchovy x x

Gerrridae Geres filamentosus threadfin silver–biddy x

Gobiidae Amoya sp. goby

Drombus globiceps goby x

Glossogobius aureus golden goby x

Glossogobius giurus flathead goby x

Glossogobius sp.2 Munro’s goby, square blotch goby x

Glossogobius sp. goby x x x

Oxuderces wirzi peacock mudskipper x

Periophthalmus argentilineatus silver-lined mudskipper x

Pseudogobius poicilosoma – x

Hemiramphidae Arrhamphus sclerolepis snub–nosed garfish x x x

Kurtidiae Kurtus gulliveri nurseryfish x

Latidae Lates calcifer barramundi x x x

Leiognathidae Leiognathus equulus common ponyfish x x x

Lutjanidae Lutjanus argentimaculatus mangrove jack x

Megalopidae Megalops cyprinoides ox-eye herring x x x

Melanotaeniidae Melanotaenia australis western rainbowfish x x x

Melanotaenia exquisita exquisite rainbowfish x x

Melanotaenia nigrans black–banded rainbowfish x

Melatotaenia splendida. australis western rainbowfish x x

Melanotaenia sp. rainbowfish x x

Mugilidae Liza alata diamond mullet x x x

Liza ordensis mullet x

Liza tade flathead mullet x x

Mugil cephalus sea mullet x x

Rhinomugil nasutus pop-eye mullet x x

Osteoglossidae Scleropages jardinii gulf saratoga x

Plotosidae Anodontiglanis dahli toothless catfish x x

Neosilurus ater black catfish, butter jew, narrow–fronted tandan x x x

Neosilurus hyrtlii Hyrtl's tandan x x x

Neosilurus pseudospinosus false–spined catfish x x

Plotosidae sp.1 eel–tailed catfish x

frc environmental




Plotosidae sp.2 eel–tailed catfish x

Porochilus rendahli Rendahl’s catfish x

Pomadasys Pomadasis kaakan barred javelinfish x

Polynemidae Eleutheronema tetradactylum blue threadfin x

Polydactylus macrochir giant threadfin x

Pristidae Pristis pristis freshwater sawfish x x

Pristis clavata dwarf sawfish x

Scatophagidae Scatophagus argus spotted scat x x

Sciaenidae Nibea soldado soldier croaker x

Nibea squamosa scaly croaker x x x

Sillaganidae Sillago lutea mud sillago x

Terapontidae Amniataba percoides barred grunter x x x

Hephaestus jenkinsi Jenkin's grunter, western sooty grunter x x x

Leiopotherapon unicolor spangled perch x x x

Scortum neili Neil’s grunter x

Syncomistes butleri Butler's grunter x x x

Syncomistes rastellus Drysdale grunter x x

Syncomistes trigonicus long–nose grunter x

Terapon jarbua crescent perch x

Tetraodontidae Marilyna meraukens merauke toadfish x x

Toxotidae Toxotes chatareus seven–spot archerfish x x x

Sources: Larson 1999; WRM 2014; TropWater 2016

frc environmental


Species of Significance to Conservation

Of the species recorded in the region, one species, the Angalarri grunter (Scortum neili),

is classified as vulnerable under the NTWC Act due to its limited distribution. While this

species is recorded from the Victoria River catchment, it is likely to be mainly restricted to

the Angalarri River (Woinarski 2006). Obbes catfish (Porochilus obbesi) is classified as

near threatened under the NTWC Act and is moderately likely to occur in the area given

its broad geographic range in northern Australia. Several sawfish and river shark species

may also occur in freshwater reaches of the Project area; however, they are discussed in

Project Sea Dragon Stage 1: Environmental Impact Statement Estuarine Receiving

Environment report (frc environmental 2016). No other freshwater fishes listed under the

EPBC Act or Fisheries Act are likely to occur in or adjoining the Project area.

Angalarri grunter

The Angalarri grunter is endemic to Australia and has been recorded from less than five

locations in the Angalarri River and the East Baines River within the Victoria River

Catchment (Allen et al. 1994). This grunter occurs in schools of up to 25 individuals

(Corbett et al. 1999) and prefers deep and wide pools with overhanging vegetation

(Corbett et al. 1999). It is generally found in water with a temperature of 21 to 28 °C and a

slightly basic pH. The diet of Angalarri grunter appears to be mainly herbivorous. During

reproduction, males guard and incubate the eggs (Breder & Rosen 1966). Key threats to

the Angalarri grunter include habitat loss due to altered flow regimes and loss of riparian

vegetation (Woinarski 2006).

Obbes catfish

Obbes catfish occurs throughout New Guinea and northern Australia, where it has been

reported from the Daly River and East Alligator River systems to the east of the study

area, and from Cape York. It prefers slow moving streams and lagoons with extensive

growth of aquatic plants (Allen et al. 2002) where it preys on invertebrates such as prawns

and molluscs.

Fish Recorded in Water Bodies on Legune Station

Due to the presence of crocodiles, fishing was limited to small baited box traps, opera

traps and line fishing. With the limited sampling effort a total of 39 fish from 11 species

frc environmental


were recorded (Table 7.3). More species and more individual fish were caught in the pre-

wet survey (October 2015) than in the post-wet season (March 2016), with most fish

caught in Alligator Creek and Forsyth Creek.

In October 2015, traps were set in Alligator Creek, Forsyth Creek, the Alligator Creek

upstream site and in Forsyth Creek Dam (sites F02, F14, F17 and F18) and 8 species

were caught. In March 2016, traps were set at each of the 5 survey sites, with 4 species

caught. All species recorded are relatively common in northern Australia; however, the

smalleye gudgeon (Prionobutis microps) (Figure 7.10), milk-spotted toadfish (Chelonodon

patoca) and a species of sole (family Soleidae) have not previously been recorded from

watercourses surrounding Legune Station (Table 7.3). No exotic species were caught or

observed in either of the surveys.

Fish caught at the sites in Alligator Creek and Forsyth Creek upstream of tidal inundation

included taxa commonly associated with estuarine areas (Gobiidae, Soleidae,

Megalopidae (Figure 7.12) and Latidae). This is indicative of high fish movement between

the fresh and estuarine sections of the creeks, likely facilitated by high connectivity in the

wet season (Pusey 2011).

All fish appeared to be healthy, with no lesions, abrasions or parasites. The low

abundance and diversity of fish recorded in these surveys is likely to be due to the limited

fishing methods and fishing effort in these surveys, and to the disturbed nature of the site.

frc environmental


Figure 7.10

Smalleye gudgeon (Prionobutis

microps) caught in Forsyth

Creek in March 2016.

Figure 7.11

Glassfish (Ambassis spp.) were

common in both surveys.

Figure 7.12

Oxeye herring (Megalops

cyprinoides) in Alligator Creek

in October 2015.

frc environmental


Table 7.3 Fish species caught on Legune Station in the 2015 dry and 2016 wet season surveys.

Family Species Common Name 2015 Dry Season 2016 Wet Season Total

F01 F02 F14 F17 F18 F01 F02 F14 F17 F18

Ambassidae Ambassis sp. glassfish 5 – 0 5 0 0 0 0 2 0 12

Ariidae Arius leptaspis triangular shield catfish,

salmon catfish

0 – 0 0 0 1 0 0 0 0 1

Arius graeffei lesser salmon catfish, blue

catfish

11 – 0 0 0 0 0 0 0 0 1

Eleotridae Prionobutis microps smalleye gudgeon 0 – 0 0 0 0 0 1 0 0 1

Mogurnda mogurnda gudgeon 1 – 0 2 0 0 0 0 0 0 3

Gobiidae Gobiidae species unidentified specimen 0 – 102 0 0 0 0 0 0 0 10

Latidae Lates calcifer barramundi 21 – 0 0 0 0 0 0 0 0 2

Megalopidae Megalops cyprinoides

oxeye herring 11 – 0 0 0 0 0 0 0 0 1

Melanotaeniidae Melanotaenia australis

rainbowfish 0 – 0 0 8 0 0 0 0 0 8

Soleidae Soleidae species unidentified specimen 0 – 12 0 0 0 0 0 0 0 1

Tetraodontidae Chelonodon patoca milk-spotted toadfish 0 – 0 0 0 2 0 0 0 0 2

Total 10 – 11 7 8 3 0 1 2 0 42

1 Caught by hook and line

2 Caught during macroinvertebrate sampling

– Site was dry in this survey

frc environmental


7.4 Aquatic Reptiles

Freshwater Turtle

Several species of freshwater turtle species have been recorded from the region,

including the:

northern long-necked turtle (Chelodina rugosa)

northern red-faced turtle (Emydura victoriae)

northern snapping turtle (Elseya dentata), and

pig nosed turtle (Carettochelys insculpta) (Cann 1998).

The northern-long-necked turtle (Chelodina rugosa) prefers slow moving and still waters

of lakes, billabongs and swamps typically with dense aquatic plants (Cann 1998). Unlike

all other freshwater turtles, this species appears to lay its eggs in saturated flooded

grounds with embryonic development beginning once water levels drop in the dry season

(Kennett et al. 1993). This species has been recorded to the west of the Project Area in

the Fitzroy River catchment and to the east in the Daly River catchment (Cann 1998). It is

likely to be on-site, particularly in areas with little or no flow, such as the turkey’s nest

dams.

Northern red-faced turtle (Emydura victoriae) have been recorded in the Victoria River and

Daly River catchments (Cann 1998) and specimens have been collected in Lake

Kununurra (Gaikhorst et al. 2011) approximately 100 km south-west of the Project area.

While little is known of the ecology of this species, it is likely to be upstream of the Project

area in freshwater reaches of the Victoria River and may be in waterholes on-site.

Northern snapping turtle (Elseya dentata) have been recorded throughout the region and

are common in the Ord, Victoria and Daly River catchments (Cann 1998). This species

inhabits deep reaches of the Victoria River as well as smaller seasonal waterholes. In the

wild their diet usually consists of herbivorous matter; however, in captivity they prefer

meat (Cann 1998). This species is likely to be upstream of the Project area in freshwater

reaches of the Victoria River and may be in waterholes on-site.

Pig nosed turtle (Carettochelys insculpta) is listed as near threatened under the TCWP

Act and has been recorded in the freshwater reaches of the Victoria, Daly, Alligator and

possibly Roper River catchments (Cann 1998). It is found in shallow, clear waters in the

dry season and in deep, turbid waters in the wet season (Doody et al. 2003). While in

Papua New Guinea and Irian Jaya pig nosed turtles are recorded from salt and brackish

Australian populations have not been(Cann 1998). This species is unlikely to be in

waterholes on-site (the Pig-nosed Turtle's morphology restricts it to river channels). Key

frc environmental


threats to this species include habitat loss due to increased water extraction and loss of

riparian vegetation (due to feral water buffalo) (TSSC 2015).

While turtles, and in particular the northern long necked turtle (Chelodina rugosa), are

likely to be on site, the water bodies on Legune Station are unlikely to provide substantial

significant habitat. In-stream habitat (i.e. woody debris and trailing tree roots) is limited

and would provide little protection from predators (i.e. crocodiles) and potential breeding

are likely to be disturbed by cattle. To date, there have been no records of any of the

species on Legune Station (ALA 2016); however, surveys in the area are likely to be

minimal.

Freshwater Crocodile

The freshwater crocodile (Crocodylus johnstoni) is listed as marine under the EPBC Act

(protect in Commonwealth waters). It is endemic to northern Australia, and is considered

common and locally abundant. Freshwater crocodiles live in inland wetlands, rivers,

creeks and billabongs, and have been recorded in the Victoria and Keep river catchments

(Delaney et al. 2010). While they occur in the upper tidal reaches of some rivers, they are

more commonly found in non-tidal freshwaters (Delaney et al. 2010). Freshwater

crocodiles show an affinity to their dry season water holes, congregating in large deep

water bodies and spreading out over the flood plains in the wet season (Greer 2006).

This species has been recorded on Legune Station; however, their abundance appears to

be decreasing (Legune Station pers. com. 2015). Further detail on the freshwater

crocodile (along with the salt-water crocodile) is in Project Sea Dragon Stage 1:

Environmental Impact Statement Estuarine Receiving Environment report (frc

environmental 2016)

Aquatic Reptiles Recorded in Water Bodies on Legune Station

In June 2015, one salt-water crocodile was observed near Blueys Pocket Paddock in the

upstream reaches of Alligator Creek (approximately 11 km south of site F17). One salt-

water crocodile was also observed in the wetland around the turkey’s nest dam at site

F20.

Both salt-water and freshwater crocodiles were observed on Legune Station at most of the

freshwater sites in January and March 2016.

No freshwater turtles were caught or observed.

frc environmental


8 Conceptual Model

A conceptual model was developed for the fresh water bodies on Legune Station (Figure

8.1).

The key characteristics are:

high catchment run-off in the wet season and after release from Forsyth Creek

Dam in August

wetland areas that tend to trap terrigenous sediment

ephemeral water bodies that become dry, stranding fauna

high concentrations of nutrients

invertebrate communities dominated by taxa common in moderately disturbed

systems

migrant and resident shorebirds, fish and reptiles feed on macroinvertebrates and

fish – capturing carbon and nitrogen

de-nitrification through the water column and sediment.

In the wet season, water from the catchment is flushed into the waterways from high flows

created by heavy rainfall and tends to pool in various wetland areas throughout the site.

This catchment run-off transports freshwater, sediment loads and detritus that have built

up during the dry season. Within the freshwater and sediments, nutrients are transported

and deposited further downstream or are deposited in wetland areas.

In the dry season, many of the wetlands dry out leaving fauna stranded. In the creeks,

water flow is reduced and often blocked at several points due to man-made road

crossings. Aquatic plant cover decreases with decreasing water levels. The

concentration of nutrients increases as water evaporates out of the ponded areas, and the

concentration of dissolved oxygen decreases.

frc environmental


Figure 8.1 Conceptual model of transport of nutrients and ecological processes in water

bodies on Legune Station.

frc environmental


9 Potential Impacts and Mitigation

Construction

Construction is planned to take approximately 2 years, with the most work in the drier

months (May to October). Construction work is expected to take place 6 days per week

for 10 to 12 hours per day (with no night work routinely planned unless schedule catch-up

is required). At peak construction, approximately 450 people will be working on the site.

The village and central facilities include facilities to accommodate these staff. All,

structures, plant, equipment, chemical storage and electrical installations will comply with

the relevant Australian Standards, or where none, international standards (including DIN

or ASTM).

The ponds, and associated channels for each farm form the majority of the footprint and

will be constructed by earthworks cutting and filling to the designed levels, followed by the

installation of the inlet, outlet and other pond structures. Once these structures have been

installed the electrical cabling will be trenched and laid in the berms around the ponds and

connected to the equipment.

The major equipment used during the construction of the ponds includes:

mainly light earthmoving equipment (laser buckets, scrapers, trucks, excavators,

compactor, graders, dozers, water carts)

cranes

trucks (delivery of materials)

plate compactors and small rollers

ditch diggers

high-density polyethylene pipe cutting, welding, equipment, and

refuelling and lube equipment.

The construction of the intake channel, settlement ponds, main feeder channel, farm

discharge channel, main discharge channel, internal farm recycling pond and access

roads will be via a cut-to-fill operation. Where subsoils are poor, provision has been made

for geotextiles to be laid, to ensure the embankments are stable.

Once the earthworks have been completed, construction of the associated structures (e.g.

filters, culverts, on- farm facilities and electrical switchyards) will commence.

frc environmental


The major equipment used during the construction of these elements includes:

earthmoving equipment (e.g. laser buckets, tractors, scrapers, trucks, excavators,

compactor, graders, dozers and water carts)

cranes, and

trucks (delivery of materials, bitumen top-coat).

The village and central facilities will be constructed by bulk earthworks, underground

services, concrete foundations, building placement or erection, building fit out, electrical

and controls and finishing civil works.

The major equipment used during the construction of these elements includes:

earthmoving equipment (e.g. scrapers, trucks, loader, compactor, graders, water

carts)

concrete batching

concrete trucks

cranes and elevated work platforms

trucks (delivery of materials, buildings), and

generators and compressors, etc.

Operation

Project Sea Dragon will grow black tiger prawns (Penaeus monodon) bred in an in-house

captive breeding program. Prawns will be grown in large grow-out ponds, with 36 to 40

ponds per farms. Stage 1 consists of three farms, each farm having up to 40 individual

10 ha ponds, which are bunded by a clay lined earth bank. Prawn harvest involves

draining the pond and capturing the prawns at the drainage point, lifting and dewatering

the prawns, and depositing them into ice slurry. The ice slurry both euthanizes and

preserves the prawns for transport to the Processing Plant.

The pond water quality will be managed by bringing in seawater from Forsyth Creek east

of the farms, internal recycling of waters after settling in Internal Farm Recycling Ponds

(IFRP), and freshwater used to reduce salinity, and therefore reduce the reliance and

therefore volume of new seawater. Water from Forsyth Creek Dam will be used to supply

freshwater to the Project.

frc environmental


Planned releases will occur via a controlled drainage system to the environment via the

Environmental Protection Zone, which will assist in polishing discharge waters, and into

Alligator Creek (Seafarms 2016).

Each farm also has a separate external bund around the perimeter of the ponds which is

constructed to a height above the pond walls to ensure failure of an individual pond does

not result into a loss across the floodplain (Seafarms 2016). For storm events less than a

50 year ARI event, any overflows are captured by a system of swales adjacent to the farm

bunds and transported to the main drainage channel for planned release. During larger

rainfall events (> 50 year ARI), the capacity of the swales may be exceeded, resulting in a

release of water into the biosecurity zones, with the excess water to be channelled along

the biosecurity zone and discharged to the tidal floodplain through a culvert under the

main discharge channel (Water Technology 2016b).

Operations personnel are planned to peak at approximately 120 people, who will be

housed in a series of single and family accommodations in the village and central

facilities.

9.1 Direct Impacts

The proposed footprint of the Stage 1 development predominantly avoids direct impacts to

the semi permanent water bodies on-site and will not extend over large water bodies,

such as Osman’s Lake. However, there will be some direct impacts to minor drainage

lines that would exist during a rainfall event in the dry season, or the start of the wet

season (and that would overflow and interact as the wet season progressed becoming

one major water body). Minor drainage lines currently occur under the settlement and

maintenance ponds, the farms and ponds, main feeder channel and roads. There is also

a major drainage line of Alligator Creek that is crossed by the road connecting the village

to the farms; however, culverts will be used the maintain flow paths here.

During the wet season (typically November to March), much of the Legune floodplain

becomes one major water body for months at a time (Water Technology 2016b). These

seasonally ephemeral wetlands are likely to provide habitat to native flora and fauna

communities during the wet season. Isolated water bodies develop in the post-wet

season providing refugial habitat for flora and fauna; and dry up completely in the dry

season. Nonetheless, loss of ephemeral wetland habitat during the wet season directly

under the project footprint may have an impact on aquatic flora and fauna communities.

Aquatic communities in these areas are typical of communities in the region and are

currently subject to high levels of disturbance from cattle on the site. The relatively small

loss of seasonal habitat is not likely to have a measurable ecological impact beyond the

Project footprint.

frc environmental


9.2 Alteration of Local Hydrology

During the dry season and start of the wet season water naturally flows in a northerly

direction towards the Keep River to the west and towards Forsyth Creek and the Victoria

River to the east of the Project. As the wet season progresses, many of these flow paths

begin to overflow and interact, with the floodplain becoming one major water body for

months at a time. Since construction of the Forsyth Creek Dam, periodic releases of

water from the dam across the floodplain occur towards the end of the dry season (July to

September) and can inundate the floodplain for one to two months depending on the

volume released and thus extend the time the floodplain water body is present. Releases

from the Forsyth Creek Dam are discharged into both the Forsyth Creek and Alligator

Creek catchments. Once entering the floodplains water spreads to fill the dry low-lying

areas. The water stored in the Forsyth Creek Dam will be used to adjust water in the

ponds and will be transported via a freshwater conveyance for use within the Project.

Therefore, there will be no late dry season releases from Forsyth Creek Dam as a result

of the Project, and flows will return to pre-dam condition.

Potential blockages to water flow from the Project include:

intake channel and settlement ponds that will bisect the Forsyth Creek floodplain

the main drainage channel and Environmental Protection Zone that will bisect the

lower Alligator Creek floodplain

a new all-weather access road that runs north-south across the floodplain and

bisects the Alligator Creek floodplain

grow out farms on the floodplain, each farm consists of between 36 and 40

individual 10 ha ponds which are bunded by a clay lined earth bank with a

separate external bund around the perimeter of the ponds which is constructed to

a height above the pond walls to ensure failure of an individual pond does not

result into a loss across the floodplain (Water Technology 2016b), and

roads over several other major and minor waterways.

The development will have no impact on typical dry season flow conditions as it doe not

alter any dry season flow paths or inundated areas (Water Technology 2016a). Wet

season flows may be impacted by construction of infrastructure, however impacts will be

mostly mitigated through the inclusion of culverts, and can be further mitigated through

appropriately placed channel works (Water Technology 2016b). Where there is

appropriate cross road drainage, such as culverts and floodways for roads, risks will be

minimised.

frc environmental


In larger rainfall events (>50 year ARI), the excess rainfall on the ponds may exceed the

capacity of the drainage swales and result in the release of excess water through a culvert

crossing under the main drainage channel. Modelling indicates this is likely to result in

shallow inundation of localised areas on the upper tidal floodplain west of the main

drainage channel, with little impact on the adjacent tidal creeks (Water Technology

2016a). This will occur when the floodplain is already affected by floodwaters and

consequently not significantly impact aquatic ecology.

As a result of ceasing the late dry season releases from Forsyth Creek Dam, flows in the

late dry season will return to pre-dam condition. As a consequence water bodies will

remain contracted over this period, and water quality will be in dry season condition for

longer, with higher nutrients and lower dissolved oxygen where water flows are restricted.

This will impact aquatic flora and fauna using the ephemeral water bodies and floodplain

wetlands as a refuge in the late dry season, as these pre dam conditions return.

9.3 Reducing Cattle Grazing

Reducing the number of cattle operating on Legune Station during Stage 1 of Project Sea

Dragon may lead to increased native vegetation and improved water quality, particularly

around and downstream of stock watering holes.

Less cattle treading on site will reduce physical damage of riparian and floodplain

vegetation and pugging of the soil. Native vegetation may grow (or be re-planted) in

areas currently heavily impacted by cattle. Reducing herbivory on native flora and the

spread of invasive flora via cattle is also likely to enhance native vegetation. Increased

native vegetation would likely reduce erosion and run-off, improving water quality,

particularly suspended sediments, turbidity and nutrients, in downstream waterways.

Reducing cattle number on Legune Station would in turn reduce urine and faeces

deposited by the cattle. This would result in less nutrients and pathogens being delivered

to the receiving waterways and may improved water quality in some areas.

9.4 Waterway Barriers

Waterway barriers may prevent or impede movements of aquatic fauna such as fish.

Many of the fish native to ephemeral systems migrate upstream and downstream, and

between different habitats at particular stages of their lifecycle. If the waterway holds

water, isolation of the waterway may also leave fish stranded; these fish will perish unless

they are relocated. Fish in the region often rely on a variety of interconnected habitats,

frc environmental


depending on the season. For example, the threatened largetooth sawfish (Pristis pristis)

spends considerable time in freshwater, moving upstream in the dry season and

downstream in the wet season (Thorburn et al. 2004; Peverell 2009).

Land clearing and treading by cattle, particularly around major watering holes, levee

banks and operational dams are currently likely to create some waterway barriers on site.

While impacts from agriculture will be reduced during Stage 1 of Project Sea Dragon,

Project infrastructure built over waterways may create impede movements of aquatic

fauna (Water Technology 2016a).

The intake channel and settlement pond will create a complete blockage to two small tidal

channels, and a partial blockage to a third. The construction will likely lead to the

formation of a new channel along the southern edge of the settlement pond and intake

channel. The intake channel is also positioned across the tidal floodplain where a number

of tidal channels cut through the bed. Construction of a structure across this area is likely

to lead to a change in the tidal drainage conditions. Some channels may increase in width

and depth to provide increased flow capacity over a shorter distance whilst others may

change path and continue along the toe of the structure (Water Technology 2016a).

Impacts of waterway barriers will be minimised where there are appropriately placed and

designed culverts and channel works on infrastructure that reduce upstream ponding and

flow conveyance, and drainage infrastructure to ensure connectivity.

9.5 Vegetation Clearing and Earthworks

Vegetation clearing and earthworks will be required during construction of the proposed

Project. The pasture will be control burned prior to earthworks commencing, and trees will

be removed and mulched (with mulch stockpiled and used for landscaping, soil

stabilisation and erosion control). No pre-stripping of topsoil is proposed, as all the

surface clay soils will be consumed in the bulk earthworks. The majority of the site has

been previously cleared for cattle grazing and consists of pastoral land.

Vegetation clearing and earthworks have the potential to impact aquatic ecology in

downstream waterways by increasing:

turbidity

sediment deposition, and

input nutrients or contaminants.

frc environmental


Risks are particularly high during times of high flow when there will be a greater risk of

erosion and run-off to the receiving environment.

While the species recorded during the field surveys are relatively tolerant of a range of

water quality conditions, inputs of turbid waters, sediments, nutrients or other

contaminants into the waterways would impact aquatic plants and animals. Increased

turbidity may negatively impact fish and macroinvertebrates, as highly turbid water

reduces respiratory and feeding efficiency (Karr and Schlosser, 1978 cited in Russell &

Hales 1993). Increased turbidity may also adversely affect free floating and submerged

aquatic plants as light penetration (required for photosynthesis) is reduced. Reduced light

penetration can also lead to a reduction in temperature throughout the water column

(DNR 1998). Increasing nutrients and other contaminants during vegetation clearing and

earthworks also has the potential to impact aquatic flora and fauna. Nutrient inputs can

lead to algae or aquatic plant blooms. During the day, as the algae photosynthesises,

these blooms can result in a high percent saturation of dissolved oxygen. However, at

night, there is a net consumption of oxygen as the algae continue to respire. This can

cause dissolved oxygen to be reduced very low during the night and early morning, which

is harmful to fauna.

The vegetation clearing and earthworks during construction may also limit the available

aquatic habitat to flora and fauna if clearing occurs near riparian areas. Aquatic fauna use

a variety of in-stream and off-stream structures for habitat including:

large and small woody debris

detritus

tree roots

boulders

undercut banks, and

in-stream, overhanging and trailing bank vegetation.

While these habitat types occur in water bodies on Legune Station, they are limited, and

unlikely to be significantly impacted by the proposed works.

In-stream habitat is an important habitat component and territory marker for many fish and

macroinvertebrates. Many species live on or around in stream habitat as it:

provides shelter from temperature, current and predators

contributes organic matter to the system, and

is important for successful reproduction.

frc environmental


Australian fish species typically spawn either on in-stream vegetation or on hard surfaces

like cobbles, boulders, and woody debris. Many fish species caught in this survey and

that are known to occur in the region, migrate upstream in periods of high flow, and the

reduction of these surfaces could impact fish movement and reproduction in the wet

season. The deposition of fine sediments can decrease in-stream bed roughness and

habitat diversity and may result in existing pools being filled in. While impacts from

agriculture (including cattle treading increasing nutrients in downstream waterways and

destroying in-stream habitat) will be reduced during Stage 1 of Project Sea Dragon,

vegetation clearing and earthworks during construction may decrease habitat available for

aquatic fauna.

However, where vegetation clearing and earthworks are managed by a comprehensive

Environmental Management Plan and appropriate mitigation is implemented, risks are

considered to be low. The risk of sediment run-off to nearby waterways will be reduced

where an Environmental Management Plan including an Erosion and Sediment Control

Management Plan is developed and implemented. This Erosion and Sediment Control

Management Plan should include, but not be limited to, the following erosion and

sediment controls:

vegetation clearing, earth works and stockpiles of soil are minimise where possible

sediment dams are constructed prior to vegetation clearing and earthworks

if required, the timing of clearing and earthworks for construction of creek

crossings is done in the dry season if possible

erosion control devices are placed in ditches and drainage lines running from all

cleared areas, especially on slopes and levee banks

contour banks, ditches or similar are formed across cleared slopes to direct run-off

towards surrounding vegetation or sediment dams, and away from waterways, and

areas that are cleared for construction, but not required to be cleared for

operations should be rehabilitated as soon as practical - replanting of native

vegetation will help reduce excess flows from occurring overland and reduce

transport of sediment into nearby waterways.

9.6 Release of Wastewater

Sewage will be treated with package Wastewater Treatment Plants (WWTP), with treated

water suitable for sustainable irrigation in land application areas on the site. There will be

three main systems:

frc environmental


Central facilities

Accommodation Village, and

Farm services.

Preliminary design of the systems, both the WWTP and land disposal areas, is provided in

Volume 1, Chapter 3 - Project Description. These systems will operate under a site wide

Recycled Water Management Plan, and will be designed and operated to comply with a

Wastewater Works Design Approval. Treatment will be undertaken in a managed system,

with regular monitoring and maintenance, with irrigation applied within the hydraulic and

nutrient assimilative capacity of the soils.

Non-sewage wastewater from the equipment wash-down area, fuel handling station, and

vehicle wash station will operate by containing wash down waters and a first flush (e.g.

first 15mm of rainfall after any wash), passing this water through an oil-water separator

prior to treatment in the on-site wastewater scheme. Subsequent run-off from these areas

will also pass through an oil-water separator before discharge to the environment.

Recovered hydrocarbons will be collected by truck pump-out, for consolidation into the

waste hydrocarbons tank at the Central Facilities, and removed off-site by a licenced

transporter to a licenced facility, or will be pumped out directly by the transporter from

each location and removed from site.

The wastewater treatment and irrigation fields along with the central facilities will be

located in the Alligator Creek catchment. If left unmitigated, wastewater has the potential

to impact aquatic ecology in the downstream freshwater water bodies via increasing input

of nutrients or contaminants (refer to Section 9.5). However, where wastewater is

managed in accordance with State and National codes and guidelines, including the

Guidelines for Wastewater Works Design Approval of Recycled Water Systems (DoH

2014) and Guidelines for Land Capability Assessment for On-site Wastewater

Management (DoH 2014), there are unlikely to be significant impacts to the freshwater

receiving environment.

9.7 Spills of Hydrocarbons and Other Contaminants

A moderate spill of hydrocarbons or other contaminants from construction vehicles or

other equipment has the potential to severely impact the local aquatic ecosystem.

Hydrocarbons, heavy metals and other contaminants can have major impacts on aquatic

communities, and can impact growth, morphology, reproduction and development of

aquatic flora and fauna. The biological effects of toxicant discharge are usually greatest in

low energy environments, such as within lakes, where accumulation and retention in fine

frc environmental


sediments can occur (Gundlach & Hayes 1978; Jackson et al. 1989). The hydrocarbon

type and concentration, together with environmental factors (e.g. wind action) and

previous exposure influence the severity of impact. Where the spill is a ‘once-off’,

recovery is likely.

Best-practice vehicle management and site management will minimise the risk of

contaminant spillage. Where the use of chemicals on the farm are minimised, chemicals

and their containers are stored, used and disposed of according to manufacturers

instruction, safety data sheets (SDS) and the requirements of State and Commonwealth

regulators, there are unlikely to be significant impacts to the freshwater water bodies.

Fuel storage and handling activities will be in accordance with AS1940 (Storage and

Handling of Flammable and Combustible Liquids) – encompassing spill containment and

response protocols. Fuels will be used on farm for vehicles and temporary generators.

Temporary generators will be equipped with double-lined day tanks. Day tanks will

replenished by a mobile diesel tanker according to demand. The fuel store will comprise a

bunded area for fuel tanks, with a drain to the oil / water separator.

Chemicals used on the farm will include hydrated lime and hydrogen peroxide, in sealed

containers. Any surplus or expired chemicals will be sent back to the main chemical store

in the Central Facilities. The company’s Chemical Management procedures will apply to

all chemicals managed at the farms. Spill kits at each chemical store will be provided, as

will training of personnel. A Hazardous Materials Register and a register of Safety Data

Sheets will be maintained for the whole project. The chemical store will comprise a metal

clad shed with concrete bunded floor, sized to contain spillage of chemicals.

Where equipment on site is regularly maintained potential leaks during operation will be

minimised.

Where these procedures are adhered to and where a comprehensive Environmental

Management Plan is designed and adhered to, the risk from spills of hydrocarbons and

other contaminants is considered to be low.

9.8 Proliferation of Pest Species

During construction, there is a high potential for mobile equipment to transport pest plants

onto the site. Seeds and plant material can be dislodged from material that has collected

on the undersides and crevices of mobile plant equipment, which can then become a

nuisance to the area.

frc environmental


Where mobile plant machinery, including boats and other aquatic vessels, is washed

down by certified weed wash-down personnel off-site, this risk will be minimised. After

construction, regular monitoring and removal of pest plants will minimise the risk of these

plants spreading.

All earthmoving equipment will be cleaned and inspected for weeds, seeds and other

contaminants prior to mobilising to Legune, and demobilising the site. Entry and exit to

farms will be strictly controlled with vehicles generally staying on-farm, only leaving for

major maintenance or replacement. The vehicle wash bay will be an automatic drive-

through bay, using benzalkonium chloride (BKC) in the spray. BKC will be diluted to

400 ppm in freshwater, and therefore suitable for disposal through the sewerage

treatment plant.

9.9 Waste and Litter

Litter and waste associated with construction and operation of the proposed development

has the potential to contribute to the degradation of water quality and is a direct hazard to

aquatic flora and fauna. For example, entanglement in debris can lead to death from

asphyxiation, abrasion, infection or reduced ability to feed or avoid predators (Laist 1997).

Ingestion of litter and debris can cause fatal blockages in the digestive system for a range

of fauna (Laist 1997).

Solid wastes from the Legune operations will include:

green waste and inert waste, from vegetation clearing and construction and

earthworks activities (though excess earth materials will be minimal)

recyclables from service areas, and maintenance activities

general and putrescible waste from the service areas

feed bags, bulk bags, and other packaging materials

wastes, such as used tyres, batteries, waste oils, sewage and grease trap sludge,

and listed wastes (though contained in hazardous waste facilities), and

farm wastes, including pond spoil and dead prawns.

Where an effective Waste and Litter Management Plan is developed for the site this risk

will be significantly reduced.

A Waste Management Plan will be implemented at the start of construction, and will

include:

frc environmental


at source and centralised rubbish receptacles and waste storage/transfer stations

an on-site landfill for putrescible and general waste

sorting of wastes such as cardboard, paper, metal, and glass and removal off-site

for recycling, and

control of hazardous or listed wastes, by storage in bunded and roofed locations,

and removal off-site by licenced transporters to sites licenced to receive these

wastes, for processing, reuse, recycling or disposal.

The residual waste stream will either be incinerated or taken to the proposed landfill,

being a depleted gravel pit. The Environmental Management Plan including landfill

management will be developed to control the waste stream.

9.10 Increased Site Access

Increased access to the site may result in higher fishing pressure, and an increase in litter.

It may also result in higher use of tracks around the site, and damage to vegetation.

This is proposed to be mitigated via installation of gates on the access road and signs to

discourage off road access.

9.11 Cumulative Impacts

Legune Station is in a remote location of northern Australia, located over 100km from the

nearest population centre. Catchment disturbances are largely low to moderate levels of

agriculture, with cattle operations on Legune Station and in the Victoria River and Keep

River catchments. A military training base is located at Bradshaw, east of the Victoria

River, and the Ord River Irrigation Area (ORIA) including the Goomig Farmlands are

within the Keep River-Border Creek catchment to the west of Legune. These projects that

are not predicted to impact the freshwater water bodies on Legune Station. Cumulative

impacts to the aquatic ecology in estuarine areas around Legune are discussed in Project

Sea Dragon Stage 1: Environmental Impact Statement Estuarine Receiving Environment

report (frc environmental 2016).

9.12 Climate Change

Climate change in the region is predicted to:

frc environmental


increased sea levels, with potential shoreline recession and increase in storm tide

elevations

increase intensity and frequency of tropical cyclones

increase average temperatures and the number of hot days (i.e. above 35oC)

increase rainfall intensity and maximum daily rainfall totals, and

increase evaporation (CSIRO 2015; Water Technology 2016a).

Climate change may lead to changes in flow regimes and timing of ephemeral water

bodies on Legune Station. With appropriate mitigation measures (including culverts and

channel works on infrastructure), impacts from the Project to freshwater water bodies on

Legune Station are considered minor and unlikely to be exacerbated with climate change.

Risks to the project associated with climate change are discussed in Water Technology

(2016a).

frc environmental


9.13 Risk Assessment

A risk assessment of potential impacts has been undertaken (Table 9.1), and a summary

of potential and residual risk is presented in Table 9.2. ‘Best practice’ assessment and

practices will be employed to minimise the impacts associated with both construction and

operation of the proposed Project. Table 9.2 provides a summary of mitigation measures

and the associated residual risk.

Table 9.1 Risk assessment matrix.

Consequence

Probability Catastrophic

Irreversible

Permanent

(5)

Major

Long Term

(4)

Moderate

Medium Term

(3)

Minor

Short Term

Manageable

(2)

Insignificant

Manageable

(1)

Almost

Certain

(5)

(25) Extreme (20) Extreme (15) High (10) Medium (5) Medium

Likely

(4)

(20) Extreme (16) High (10) Medium (8) Medium (4) Low

Possible

(3)

(15) High (12) High (9) Medium (6) Medium (3) Low

Unlikely

(2)

(10) Medium (8) Medium (6) Medium (4) Low (2) Low

Rare

(1)

(5) Medium (4) Low (3) Low (2) Low (1) Low

frc environmental


Table 9.2 Summary of potential impacts on freshwater ecosystems. C

on

str

uc

tio

n

Op

era

tio

n

Potential Impact Mitigation Measure Monitoring Significance of Impact (Unmitigated) Significance of Residual (Mitigated

Impact)

Direct impacts to minor and major drainage lines

Limiting the area of disturbance (project footprint) where possible and exclude larger

waterbodies (such Osman’s Lake)

using the project footprint for any temporary construction and storage

use of culverts or other measures to maintain connectivity for major waterways

None Water quality (9) Medium

Macroinvertebrates (15) High

Aquatic plants (15) High

Mobile biota, including TPWC listed species (10) Medium

Water quality (4) Low

Macroinvertebrates (10) Medium

Aquatic plants (10) Medium

Mobile biota, including TPWC listed species (4) Low

Alteration of local hydrology Appropriately placed and designed culverts and channel works on infrastructure to

reduce upstream ponding and allow water to flow to Alligator Creek.

Where there is appropriate cross road drainage, such as culverts and floodways,

impacts to roads, water bodies and ephemeral wetlands, and flood risk will be

minimised.

Water quality and

macroinvertebrates

Water quality (9) Medium





Macroinvertebrates (4) Low

Aquatic plants (4) Low


Waterway barriers Culverts and channel works on infrastructure to reduce upstream ponding and flow

conveyance and drainage infrastructure to ensure connectivity

Water quality and

macroinvertebrates









Runoff from vegetation clearing and earthworks

Construction predominantly in the dry season

Sediment and Erosion Management Plan (EMP)

Water quality and

macroinvertebrates




Mobile biota, including TPWC listed species (12) High





Release of wastewater Sewage treatment and irrigation

Adhere to State and National codes and guidelines

Wastewater Management Plan (EMP)

Water quality and

macroinvertebrates









Spills of hydrocarbons and other contaminants

Minimise the use of hydrocarbons and chemical where possible

Best-practice vessel and vehicle management and site management

Fuel storage and handling activities will be in accordance with AS1940

Spill kits, training of personnel and a Hazardous Materials Register, a register of MSDS

Any fuel, oil or chemical spills are contained and cleaned up immediately

Spill Management Plan (EMP)

Water quality and

macroinvertebrates









Proliferation of pest species

Wash down of plant machinery and equipment

Washing vehicles with BKC on entry and exit of site

None Water quality (4) Low








frc environmental


Co

ns

tru

cti

on

Op

era

tio

n

Potential Impact Mitigation Measure Monitoring Significance of Impact (Unmitigated) Significance of Residual (Mitigated

Impact)

Litter and waste Waste Management Plan (EMP)

Water quality and

macroinvertebrates









Increased site access

Site access restrictions None Water quality (2) Low








frc environmental


10 Environmental Management and Monitoring

Environmental monitoring is required throughout the life of the project to determine the

effectiveness of the mitigation measures put in place. The monitoring program is

designed to be able to detect change should operational or construction activities affect

water quality or aquatic ecology.

During both construction and operation, it is recommended that water quality and

macroinvertebrates are monitored in water bodies at the sites in Table 10.1 at least twice

per year (late dry season and late wet season). Macroinvertebrate communities are an

important indicator species as they reside in an aquatic system long enough to reflect

chronic effects, yet short enough to respond to relatively acute changes in water quality.

They also have a relatively limited mobility so are generally unable to move away from

adverse impacts. While monitoring water quality will provide an assessment of any

impacts during the sampling event, monitoring macroinvertebrate communities will assist

in indicating any long-term impacts.

Table 10.1 Proposed water quality and aquatic plants and macroinvertebrate sites.

Site Latitude Longitude Description

F01 -15.17062 129.34354 Alligator Creek upstream of tidal influence, important for

waterbirds

F02 -15.08223 129.39307 Ephemeral wetland

F03 -15.08242 129.39184 Turkey’s nest dam

F14 -15.07463 129.41932 Forsyth Creek, upstream of direct tidal influence, used by

waterbirds

F17 -15.20662 129.38450 Alligator Creek, upstream site that is important to waterbirds

F18 -15.21969 129.46143 Forsyth Creek Dam. Water from the Dam is released in the

late wet season.

10.1 Water Quality


low dissolved oxygen, high turbidity and high nutrients in the dry and pre-wet seasons. In

Forsyth Creek Dam water quality was poorest in the pre-wet season, with low dissolved

oxygen and higher nutrients at this time. Water quality in the ephemeral wetlands was

poor to moderate, and characterised by low dissolved oxygen and high turbidity,

particularly in the remaining water in the dry season.

frc environmental


The maximum concentration of total and dissolved metals and metalloids, and in particular

aluminium, arsenic and boron, were sometimes above AWQG trigger levels for further

investigation. Other potential contaminants (e.g. hydrocarbons and pesticides) were all

below the AWQG, with the exception of C15-C28 hydrocarbons at site F15.

Parameters to be monitored have been selected with regard to:

likely impacts from the proposed development

potential existing anthropogenic impacts, and

holding times before analysis.

Monitoring will include assessment of:

physical and chemical stressors

chlorophyll a

recoverable hydrocarbons, and

pesticides.

As the concentrations of recoverable hydrocarbons and pesticides were low, any increase

over background may be indicative of an impact from the proposed development.

Samples will be collected and analysed as indicated in Section 2.3 and compared to

appropriate AWQG and existing data. The parameters and sites monitored will be

reviewed after two years of operation, and a revised monitoring plan developed if

required.

10.2 Environmental Management Plan

Environmental risks to aquatic ecology of water bodies on Legune Station should be

managed under the Environmental Management Plan, which incorporates an appropriate:


Erosion and Sediment Management Plan

Acid Sulfate Soil Management Plan (where appropriate)


Waste Minimisation and Management Plan, and

Spill Management Plan.

frc environmental



The Wastewater and Stormwater Management Plan should detail waste and stormwater

treatment. It should also incorporate a Water Quality Management Plan that:

describes baseline water quality in the vicinity of the proposed works

establishes key performance criteria

describes a monitoring plan for water quality, and

describes a contingency plan with corrective actions for any exceedence in

performance criteria.

Erosion and Sediment Management Plan and Acid Sulfate Management Plan

Risks associated with the disturbance of sediment and soils will be minimised where the

following plans are designed and implemented:

Erosion and Sediment Management Plan (including a sediment sampling and

analysis plan, and plans for the handling and disposal of marine sediments), and

Acid Sulfate Soil Management Plan (where appropriate).

Items for consideration in these plans include (but should not be limited to):

minimisation of disturbance of sediment in the waterway

minimisation of the movement and transfer of any sediment

where there is a significant risk, the disturbance areas are effectively isolated, for

example by using silt curtains, oil spill booms, bunding, trenching and / or similar

technologies

identification of acid sulfate soils, through a sediment sampling and analyses plan,

(where appropriate)

construction plans that minimise the disturbance and appropriately treats or

disposes of Acid Sulfate Soils (where appropriate), and / or

water quality monitoring during construction, including the use of ‘trigger levels’ to

trigger reactive management to effectively control suspended solids concentrations

in adjoining waters.

frc environmental



The risk associated with the introduction of pests is considered low where an appropriate

Pest Management Plan is developed. To reduce the risk of inadvertently spreading pests,

equipment should be washed down. All earthmoving equipment will be cleaned and

inspected for weeds, seeds and other contaminants prior to mobilising to Legune, and

demobilising from the site. Entry and exit to farms will be strictly controlled with vehicles

generally staying on-farm, only leaving for major maintenance or replacement. The

vehicle wash bay will be an automatic drive-through bay, using benzalkonium chloride

(BKC) in the spray. BKC will be diluted to 400 ppm in freshwater, and therefore suitable

for disposal through the sewerage treatment plant.

After construction, regular monitoring and removal of pest plants will minimise the risk of

these plants spreading.

Waste Minimisation and Management Plan

Measures to reduce the introduction of waste, debris and litter should be developed as

part of the Waste Minimisation and Management Plan. This may include measures such

as:

waste storage facilities secured to avoid removal of waste

reduction of waste at the source, reuse and recycling as well as recovery of

materials or conversion of waste into useable materials, and

educational signage, explicitly stating the risk to wildlife of disposing rubbish in the

water.

Spill Management Plan

The Spill Management Plan should include:

all refuelling to the site is by licensed fuel suppliers in accordance with their

Standard Operating Procedures

refuelling takes place in accordance with industry standards

the stored volume of fuel, oil or chemical is minimised, with storage in a secure

area

frc environmental


any visible (or suspected) fuel, oil or chemical loss will be treated as an ‘incident’,

and

regular checks of equipment for evidence of leaks and for the condition of hoses

and seals, and maintain or repair as necessary to prevent drips, leaks or likely

equipment failures.

frc environmental


11 References

ALA. 2016. Atlas of Living Australia [Online]. Available: http://www.ala.org.au [Accessed

30 August 2016].

Allen, G. R. 1989. Freshwater Fishes of Australia, T.F.H. Publications, USA.

Allen, G. R., Larson, H. K. & Midgley, S. H. 1994. A new species of Scortum Whitley

(Pisces: Terapontidae) from the Northern Territory, Australia. The Beagle,

Records of the Museums and Art Galleries of the Northern Territory, 10, 71-74.

Allen, G. R., Midgley, S. H. & Allen, M. 2002. Field guide to the freshwater fishes of

Australia, Western Australia Museum, Western Australia.

ANZECC & ARMCANZ 2000. Australian and New Zealand Guidelines for Fresh and

Marine Water Quality, National Water Quality Management Strategy, Australian

and New Zealand Environment and Conservation Council & Agriculture and

Resource Management Council of Australia and New Zealand.

Arthington, A. H., Balcombe, S. R., Wilson, G. A., Thoms, M. C. & Marshall, J. C. 2005.

Spatial and temporal variation in fish assemblage structure in isolated waterholes

during the 2001 dry season of an arid-zone floodplain river, Cooper Creek,

Australia. Marine and Freshwater Research, 56, 1-11.

Balcombe, S. R. & Arthington, A. H. 2009. Temporal changes in fish abundance in

response to hydrological variability in a dryland floodplain river. Marine and

Freshwater Research, 60, 146-59.

Bennett, D. & George, R. 2014. Goomig Farmlands development Baseline water quality in

the lower Keep River, Department of Agriculture and Food, Western Australia.

Bennett, D. & George, R. J. 2011. Surface Water Characteristics of the Weaber Plain and

lower Keep River Catchments: data review and preliminary result, Department of

Agriculture and Food, Western Australia.

Bishop, K. A. 1995. Studies on fish movement dynamics in a tropical floodplain river:

Prerequisites for a procedure to monitor the impacts of mining. Austral ecology,

20, 81.

Bishop, K. A. & Forbes, M. A. 1991. The freshwater fishes of Northern Australia. In:

Haynes, C. D., Ridpath, M. G. & Williams, M. A. J. (eds.) Monsoonal Australia:

http://www.ala.org.au/

frc environmental


Landscape, Ecology and Man in the Northern Lowlands. A. A. Balkema:

Rotterdam.

Breder, C. M. & Rosen, D. E. 1966. Modes of Reproduction in Fishes, T.F.H. Publications,

Jersey City.

Cann, J. 1998. Australian Freshwater Turtles, Beaumont Publishing Pty Ltd, Singapore.

Chessman, B. 2003. Signal 2 A Scoring System for Macro-Invertebrates ('water-bugs') in

Australian Rivers. Monitoring River Health Initiative Technical Report Number 31.

User Manual Version 4 ed. Canberra: Commonwealth of Australia.

Clarke, K. R. & Warwick, R. M. 2001. Change in Marine Communities: an Approach to

Statistical Analysis and Interpretation, PRIMER-E, Plymouth.

Corbett, L., Batterham, R. & Sewell, S. 1999. Bradshaw field training area. Additional

studies: Angalarri grunter, Report prepared for Department of Defence (ERA

Environmental Services Pty Ltd, Darwin).

CSIRO 2015. Climate Change in Australia Projections, Cluster Report – Monsoonal North.

Delaney, R., Fukuda, Y., Neave, H. & Saalfeld, W. 2010. Management Program for the

Freshwater Crocodile (Crocodylus Johnstoni) in the Northern Territory of

Australia, 2010-2015, Department of Natural Resources, Environment, the Arts

and Sport.

DERM 2010. Monitoring and Sampling Manual 2009 Environmental Protection (Water)

Policy 2009 Version 2 September 2010. Brisbane: Department of Environment

and Heritage Protection.

DNR 1998. Fitzroy Basin Water Allocation and Management Planning, Technical Reports.

A Summary of information and analyses conducted for the WAMP process to

date in the Fitzroy Basin, Department of Natural Resources.

DoH 2014. Guidelines for Wastewater Works Design Approval of Recycled Water

Systems. 1 November 2013., Department of Health.

Doody, J. S., West, P. & Georges, A. 2003. Beach selection in nesting pig-nosed turtles,

Carettochelys insculpta. Journal of Herpetology, 37, 178-182.

Douglas, M., Jackson, S., Setterfield, S., Pusey, B., Davies, P., Kennard, M., Burrows, D.

& Bunn, S. 2011. Northern futures: threats and opportunities for freshwater

ecosystems. In: Pusey, B. (ed.) Aquatic biodiversity in northern Australia:

patterns, threats and future.

frc environmental


EHMP 2007. Ecosystem Health Monitoring Program 2005-2006, Annual Technical Report.

Brisbane: South East Queensland Healthy Waterways Partnership.

Finlayson, C. M., Bailey, B. J., Freeland, W. J. & Fleming, M. 1988. Wetlands of the

Northern Territory. In: McComb, A. J. & Lake, P. S. (eds.) The Conservation of

Australian Wetlands. Surrey Beatty & Sons: Sydney.

frc environmental 2015a. Project Sea Dragon Stage 1 Proposed Estuarine and

Freshwater Ecological Baseline Program, CO2 Australia Limited.

frc environmental 2015b. Project Sea Dragon Stage 1 Proposed Water Quality Program ,

CO2 Australia Limited.

frc environmental 2016. Project Sea Dragon Stage 1: Environmental Impact Statement

Estuarine Receiving Environment, CO2 Australia Limited.

Gaikhorst, G. S., Clarke, B. R., McPharlin, M., Larkin, B., McLaughlin, J. & Mayes, J.

2011. The captive husbandry and reproduction of the pink-eared turtle (Emydura

victoriae) at Perth Zoo. Zoo Biology, 31, 79-94.

Garcia, E., Dostine, P., Humphrey, C., Douglas, M., Pusey, B. & Cook, B. 2011. Aquatic

invertebrates. In: Pusey, B. (ed.) Aquatic biodiversity in northern Australia:

patterns, threats and future. Charles Darwin University: Australia.

Gooderham, J. & Tsyrlin, E. 2002. The Waterbug Book, CSIRO Publishing, Victoria.

Greer, A. E. 2006. Encyclopedia of Australian Reptiles : Crocodylidae [Online]. Australian

Museum. Available: http://australianmuseum.net.au/freshwater-crocodile -

sthash.6TdqjzeE.dpuf [Accessed 12/06/16].

Gundlach, E. R. & Hayes, M. O. 1978. Vulnerability of coastal environments to oil spill

impacts. Marine Technology Society Journal, 12, 18-27.

Jackson, J. B. C., Cubit, J. D., Keller, D. B., Batista, V., Burns, K., Caffey, H. M., Caldwell,

R. L., Garrity, S. D., Getter, C. D., Gonzalez, C., Guzman, H. M., Kaufmann, K.

W., Knap, A. H., Levings, S. C., Marshall, M. J., Steger, R., Thompson, R. C. &

Weil, E. 1989. Ecological effects of a major oil spill on Panamanian coastal

marine communities. Science, 243, 37-44.

Kennett, R., Georges, A. & Palmerallen, M. 1993. Early Developmental Arrest During

Immersion of Eggs of a Tropical Fresh-Water Turtle, Chelodina-Rugosa

(Testudinata, Chelidae), From Northern Australia. Australian Journal of Zoology,

41, 37-45.

http://australianmuseum.net.au/freshwater-crocodile#sthash.6TdqjzeE.dpuf

http://australianmuseum.net.au/freshwater-crocodile#sthash.6TdqjzeE.dpuf

frc environmental


Kirby, S. L. & Faulks, J. J. 2004. Victoria River catchment: An assessment of the physical

and ecological condition of the Victoria River and its major tributaries,

Department of Infrastructure, Planning and Environment.

Laist, D. W. 1997. Impacts of marine debris: entanglement of marine life in marine debris

including a comprehensive list of species with entanglement and ingestion

records. Marine Debris, 99-139.

Larson, H. 1999. Keep River Aquatic Fauna Survey. Museums and Art Galleries of the

Northern Territory.

Lloyd, J. & Cook, S. 2002. Australia-Wide Assessment of River Health: Northern Territory

AusRivAS Sampling and Processing Manual, Monitoring River Heath Initiative

Technical Report no 19, Commonwealth of Australia and Department of Lands,

Planning and Environment.

Low-McConnell, R. H. 1975. Fish communities in tropical freshwaters; their distribution,

ecology and evolution, Longman, London.

McConnell, R. & Lowe-McConnell, R. H. 1987. Ecological studies in tropical fish

communities, Cambridge University Press.

Morris, K. & Reich, P. 2013. Understanding the relationship between livestock grazing and

wetland condition. Arthur Rylah Institute for Environmental Research Technical

Report Series No. 252, Department of Environment and Primary Industry,

Heidelberg, Victoria.

NT Government. 2016. Important biodiversity conservation sites [Online]. Available:

https://nt.gov.au/environment/environment-data-maps/important-biodiversity-

conservation-sites/conservation-significance-list [Accessed 26/04/16 2016].

Pettit, N., Townsend, S., Dixon, I. & Wilson, D. 2011. Plant communities of aquatic and

riverine habitats. In: Pusey, B. J. (ed.) Aquatic Biodiversity in Northern Australia:

patterns, threats and future. Charles Darwin University Press: Australia.

Peverell, S. C. 2009. Sawfish (Pristidae) of the Gulf of Carpentaria, Queensland,

Australia. Masters (Research), James Cook University.

Pusey, B., Warfe, D., Townsend, S., Douglas, M., Burrows, D., Kennard, M. J. & Close, P.

2011. Condition, impacts and threats to aquatic biodiversity. In: Pusey, B. (ed.)

Aquatic biodiversity in northern Australia: patterns, threats and future. Charles

Darwin University: Australia.

frc environmental


Pusey, B. J. 2011. Aquatic biodiversity in northern Australia: patterns, threats and future,

Charles Darwin University Press, Darwin.

Russell, D. J. & Hales, P. W. 1993. Stream Habitat and Fisheries Resources of the

Johnstone River Catchment. Northern Fisheries Research Centre: Queensland

Department of Primary Industries.

SEWPAC. 2012. Environment Protection and Biodiversity Conservation Act 1999.

Environmental Offsets Policy [Online]. [Accessed].

Simpson, S. L., Batley, G. B. & Chariton, A. A. 2013. Revision of the ANZECC/ARMCANZ

Sediment Quality Guidelines. CSIRO Land and Water Science Report 08/07.

CSIRO Land and Water.

Simpson, S. L., Batley, G. E., Chariton, A. A., Stauber, J. L., King, C. K., Chapman, J. C.,

Hyne, R. V., Gale, S. A., Roach, A. C. & Maher, W. A. 2005. Handbook for

Sediment Quality Assessment, CSIRO, Lucas Heights, NSW.

Thorburn, D. C., Morgan, D. L., Rowland, A. J. & Hill, H. 2004. Elasmobranchs in the

Fitzroy River, Western Australia, Report to the Natural Heritage Trust, Murdoch

University.

Tickel, S. J. & Rajaratnam, L. R. 1995. Legune Station: Water resources survey of the

western Victoria River district, Power and Water Authority, Water Resources

division.

Townsend, S. A. 2006. Hydraulic phases, persistent stratification, and phytoplankton in a

tropical floodplain lake (Mary River, northern Australia). Hydrobiologia, 556, 163-

179.

Townsend, S. A., Boland, K. T. & Wrigley, T. J. 1992. Factors contributing to a fish kill in

the Australian wet / dry tropics. Water Research, 26, 1039-1044.

TSSC 2015. Pig-nosed Turtle (Carettochelys insculpta), Advice to the Minister for the

Environment and Heritage from the Threatened Species Scientific Committee

(TSSC) on Amendments to the list of Threatened Species under the Environment

Protection and Biodiversity Conservation Act 1999 (EPBC Act) 13 July 2005.

Ward, D. P., Pusey, B., Brooks, A., Olley, J., Shellberg, J., Spencer, J. & Tews, K. 2011.

River landscapes and aquatic systems diversity. In: Pusey, B. (ed.) Aquatic

biodiversity in northern Australia: patterns, threats and future. Charles Darwin

University Press: Australia.

frc environmental


Warfe, D. M., Pettit, N. E., Davies, P. M., Pusey, B. J., Hamilton, S. K., Kennard, M. J.,

Townsend, S. A., Bayliss, P., Ward, D. P., Douglas, M. M., Burford, M. A., Finn,

M., Bunn, S. E. & Halliday, I. A. 2011. The ‘wet–dry’ in the wet–dry tropics drives

river ecosystem structure and processes in northern Australia. Freshwater

Biology, 56, 2169-2195.

Water Technology 2016a. Project Sea Dragon Environmental Impact Assessment Coastal

Environment and Water Quality. September 2016, CO2 Australia.

Water Technology 2016b. Project Sea Dragon Stage 1 Legune Grow-out facility:

Floodplain Surface Water Assessment, CO2 Australia.

Woinarski, J. 2006. Threatened species of the Northern Territory, Angalarri grunter

Scortum neili. Darwin, Northern Territory: Parks and Wildlife Commission,

Department of Natural Resources, Environment and the Arts, Northern Territory

Government.

WRM 2010. Lower Keep River Interim Water Quality Trigger Values, Report by Wetland

Research & Management to Benchmark Projects Australasia, Western Australia.

WRM 2014. ORIA Stage II – Keep River Baseline Aquatic Fauna and Targeted Sawfish

Survey September/October 2013. Unpublished report to LandCorp prepared by

Wetland Research & Management. Final report v3, 8 May 2014.

frc environmental


12 Additional Information

12.1 People Involved in Preparing this Document

frc environmental staff involved with preparing this document are outlined in Table 12.1.

Table 12.1 frc environmental staff who prepared this report and / or completed field

surveys.

Name Position Qualifications Project

Involvement

Carol Conacher Senior Principal

Ecologist

Bachelor of Science – Sydney University

30 years industry experience

Technical report

review, report writing,

quality control and

quality assurance

Dr John

Thorogood

Senior Principal

Ecologist

Master of Science – University of Sydney

Doctor of Philosophy (Physiology) –

University of Queensland


Field surveys

Dr Craig

Chargulaf

Senior Ecologist Bachelor of Science – University of

California (Davis)

Doctor of Philosophy (Marine Science) –



Report writing, data

analysis, field

surveys, laboratory

identification of

macroinvertebrates

Dr Elizabeth West Senior Ecologist Doctor of Philosophy – Griffith University


Report writing

Dr Christoph

Braun

Graduate

Ecologist

Bachelor of Science – University of

Tuebingen (Germany)

Doctor of Philosophy (Marine Science) –



Report writing, data

entry and analysis,

field surveys

Cameron Forward Senior Ecologist Bachelor of Marine Science – University

of Queensland


Mapping, data entry

and analysis, data

curation

Dr Benjamin Cook Principal

Ecologist

(Freshwater)

Bachelor of Applied Science – University

of Queensland

Bachelor of Science (First Class

Honours) – Griffith University

Doctor of Philosophy (Australian

Freshwater Ecology) – Griffith University


Technical report

review

Documents

PROJECT SEA DRAGON STAGE 1 LEGUNE GROW … · Project Sea Dragon Stage 1: Environmental Impact Statement – Freshwater Ecology and Water Quality i Summary ... approximately 330 km