__________________________________________________________________________________________1 Centre for Resource and Environmental Studies, The Australian National University, Canberra ACT 0200.

Phone: (02) 6285 1862, Fax: (02) 6125 0757, E-mail: lachlan@cres.anu.edu.au2 Integrated Catchment Assessment and Management Centre, The Australian National University.

Design of Water Quality Monitoring Programs and Automatic SamplingTechniques

Lachlan T. H. Newham1, Barry F. W. Croke1, 2 and A. J. Jakeman1

SUMMARY: An important means of characterising the health of streams is through the measurement of the sedimentand nutrient fluxes that they transport. Cost effective and targeted water quality monitoring programs are required toproperly quantify both the total loads and temporal distribution of these fluxes at catchment scales. Careful analysis ofdata from such programs ensures ameliorative efforts to reduce the biological, chemical and physical impacts of highloads are targeted to have the best effect.

This paper reports on the development of a monitoring program in tributaries of the upper Murrumbidgee River. Theaim of the program is to provide data for the modelling of both nutrient and sediment loads transported from uplandcatchments. The objective of the modelling is to spatially identify sediment transport and storage dynamics togetherwith source strength variations in upland catchments. A brief review of design considerations for water quality programsis made with reference to the Murrumbidgee case study. The tools, techniques and sites of an alternative monitoringprogram in tributaries of the upper Murrumbidgee River are detailed. Included in the paper are modifications to thedesign of Graczyk et al. (2000) for an inexpensive, rising-stage water quality sampler, suitable for Australian conditionsand currently in use. The research demonstrates that water quality data can be collected simply and cost effectively ifprograms are appropriately designed.

THE MAIN POINTS OF THIS PAPER• Water quality data spanning a range of hydrologic conditions are required for effective stream health management.• Current water quality sampling programs are not providing data commensurate with investment.• Better design of sampling programs and sample collection methods, for example the use of an inexpensive rising-

stage samplers, can improve the utility of the data collected.• The design of a rising-stage siphon sampler, modified for Australian conditions is presented.

1. INTRODUCTIONMonitoring stream water quality is an important toolfor the quantification of the health of a stream.Effective water quality monitoring programs providethe basis to calculate loads of material exported fromcatchments including sediments, nutrients, pesticidesand other pollutants. This information is important foreffective siting of ameliorative effort and for associatedresearch and modelling. Collection and analysis ofwater quality data is expensive. Unfortunately muchinvestment in collection and analysis is ineffective inproviding information to assist in reaching managementoutcomes.

Using the upper Murrumbidgee catchment as a casestudy this paper will demonstrate the inadequacies ofpresent monitoring programs for estimation of totalloads of sediments, nutrients and other pollutants. Thepaper will then describe a cost-effective alternative forthe provision of high quality data for accurate loadestimation. That part of the paper will show the designof an event based water quality sampling program andthe use of low cost siphon sampling equipment in theMolonglo and Gudgenby Rivers of the Canberraregion. Results from a prototype sampler and adiscussion of the program will then be presented.

2. WATER QUALITY MONITORING:MURRUMBIDGEE CASE STUDYThe Murrumbidgee River catchment upstream of theBurrinjuck Dam is used as a case study for evaluationof stream water quality monitoring. The uplandcatchment has an area of 13,090km2 and a populationof approximately 390,000. There is growing concernover reduced water quality in the catchment, which ispart of the Murray-Darling basin (MurrumbidgeeCatchment Management Committee, 1998).

Water quality data is collected over the catchment by avariety of organisations for multiple purposes.Examples of the programs in place include:! The NSW Department of Land and Water

Conservation has funding of $1.6 million over sixyears for the unregulated parts of theMurrumbidgee River catchment (Nancarrow, perscom 2001). For the upper Murrumbidgeecatchment, this represents an investment ofapproximately $95,238 per annum for physical andchemical water quality sampling and analysis.

! Environment ACT invests $25,795 in monitoringchemical and physical water quality of streams andrivers within the upper Murrumbidgee annually. Afurther $25,731 is invested in monitoring the waterquality of the ACT urban lakes and $11,411 isspent on macroinvertebrate monitoring(Wilkinson, pers com 2001).

! Environment ACT is improving the utility of thedata they collect by shifting from a predominantlyroutine sampling program to include more event-based sampling.

! ActewAGL’s activities in water quality monitoringare primarily concerned with the provision ofresidential water supply to the Canberra region.

! The ACT Department of Health, Housing andCommunity Care has a water quality testingprogram in place to assess the quality of water forrecreational purposes primarily in the urban lakesof the ACT.

! The National Capital Authority conduct waterquality monitoring in Lake Burley Griffin andinflows. Their testing includes physical, biologicaland chemical analysis. Selected swimming sites aretargeted with additional bacteriological sampling.

! The catchment is also an important study area forresearch by organisations that do not have directmanagement roles. A number of universities andorganisations such as the CSIRO and Landcarecollect water quality information in the catchmenthowever, it is difficult to quantify their totalinvestment.

Each of the organisations has a predominantly routinestream sampling program presently in place. Routinesamples are collected at set intervals and generally takeno account of the hydrologic or antecedent conditions.According to Letcher et al. (1999) less confidence maybe placed on loads estimated using data with a widesampling interval or a sampling interval that does notcharacterise flood events. Routine sampling is thuslargely ineffective for the purposes of sediment andnutrient load estimation due to the predominance ofsampling at low flow conditions. Only the prevailingambient quality of a water body is determined by thesemeans.

In summary, more than $150,000 is invested annuallyin water quality investigations for the catchment. Thecatchment has fewer than ten sites with data of anappropriate quality for effective estimation of sedimentand nutrient loads. This is because of the generallyroutine sampling program in place and the fact thatsome sampling sites are not located in the vicinity ofstream gauges. This result is unacceptable and alternateapproaches are needed.

3. AN ALTERNATE APPROACHThe remainder of this paper illustrates potentialmethods available to overcome some of themethodological and design inadequacies of currentwater quality programs for the estimation of pollutantloads and assessment of stream health. This isapproached by description of an alternate water qualitysampling program at a scale and budget commensuratewith a PhD study.

3.1 Aims and ObjectivesClear objectives for water sampling programs need tobe established prior to commencement of sampling(Sanders et al., 1983). The aim of the programpresented in this paper is to provide data for accuratecalculation of loads of sediments and nutrients fortesting SedNet - a landscape-based sediment andnutrient estimation model. A secondary aim of theprogram is to illustrate alternate sample collectionmethods and design of water quality programs.

The SedNet model has been developed to spatiallyidentify transport and storage dynamics together withsource strength variations of catchments, see Prosser etal. (in prep). Research into the structure andparameterisation of the SedNet model is in progress.Long-term estimates of sediment and nutrient loads arerequired to assess the accuracy of the SedNet model.To develop these estimates a function relating sedimentand nutrient concentrations to flow will be developedfrom the data collected in this monitoring program. Along-term hydrologic record will be reconstructedusing the IHACRES rainfall-runoff model calibratedfor each site. Sediment and nutrient loads will then becalculated using the aforementioned function and long-term streamflow reconstruction. The testing of theSedNet model will be supplemented by geochemicaltracing of materials, fieldwork and other spatialanalysis. See Newham et al. (in prep) for a moredetailed discussion of associated accuracy assessmentand model sensitivity trials.

In the Australian context – a continent with highlyvariable rainfall and streamflow, there are two crucialdesign factors in the construction of water qualitymonitoring programs. These are the location ofsampling stations (Sanders et al., 1983) and the type orfrequency of sampling. The following sections considerthese in turn.

3.2 Site SelectionFor the program presented here sites for monitoring ofwater quality were selected based on the followingcriteria:! it was necessary that sites be co-located with a

continuously recording stream gauge. This was toensure that streamflow could be determined at thetime of sampling and hence loads calculated;

! it was preferable that sites were telemetered andaccess to this data was available. The reasons forthis will become apparent in the following section,which discusses an event-based sampling regime;

! it was necessary that sites have vehicular access inwet weather;

! preference was given to sites close to Canberra;and

! it was preferable that sites be nested to investigatepollutant transport of individual river reaches.

A short list of catchments was then made. To ensurevariety in physical characteristics, attributes such astopography, land use and preliminary results of alandscape based modelling exercise were considered inselection from this shortlist. Four sites were selected. A

map showing the locations of the sites is shown inFigure 1. Fortunately with the cooperation of ourindustry partners we are able to access telemeteredstream level data at or nearby each of the sites. Thiswill enable timely collection of water quality samples.

Figure 1: Map of water quality sampling sitesincluding labelling of name and number of gauge.

3.3 Sampling StrategyThe sampling program is expected to run for amaximum of 18 months. For a program of this length itis suggested by Robertson and Roerish (1999) to have acombined event-based and monthly routine sampling.This has been established. Event-based samplingprograms collect discrete samples throughout runoffevents and comprise both rising and falling limbs of thestream hydrograph. The aim of event monitoring is tomeasure the water quality of a stream during orfollowing a runoff-producing rainfall event. Risingstage conditions, in particular, are generally notsampled adequately with a manual-sampling programdue to their rapid rise. In the Australian context, therationale for the collection of samples during runoffevents is that the majority of material is exported fromcatchments during these periods (Croke and Jakeman,2001). The approach of our program is to collect risingstage samples using a siphon sampler (described in thefollowing section); routine and falling stage samplesare to be collected by manual ‘grab’ samples. Theroutine sampling program also enables maintenance ofthe samplers including removal of any fouling of theintake or sample collection bottles however, this hasnot been a problem to date.

samplecollection bottle

110mm Ø PVCpipe

8mm Ø vinyltube

coupling andscrew cap

rubber stopper

exhaust

intake

310mm

200mm

360mm

150mm

Figure 2: Schematic design of a rising-stage automaticwater quality sampler (modified from Graczyk et al.(2000)).

4. RISING STAGE WATER QUALITY SAMPLERSiphon samplers are low-cost alternatives to automaticmechanical samplers used to collect event-based water-quality samples. This section describes a rising-stagesiphon water sampler. The design of the sampler wasmodified for Australian conditions from Graczyk et al.(2000). This new design of the sampler is shown inFigure 2. The approximate cost of each of the samplersis $60, mechanical automatic samplers are expensivegenerally priced from around $2000 (not includinginstallation). The siphon samplers are easy to constructand secure instream using simple tools. The operationof the samplers is also simple. As water level rises tothe elevation of the intake tube, water enters the 8mm-vinyl tube. As the stream continues to rise, watercontinues to move up the intake tube until it reaches thetop of the loop; at this point a siphon is created and thebottle starts to fill. The sample collection bottle fillsrapidly under a hydraulic head with displaced air

escaping through the exhaust tube. Once full, changesin the water level do not significantly affect thecontents in the bottle. Following an event, the bottlesare collected and the contents analysed. Severalsamplers can be installed at different levels at each siteto collect samples throughout the anticipated range inwater levels with a bias toward high flows. Samplerswere positioned at stream gauge sites with continuousmonitoring of streamflow. Figure 3 shows the height ofsamplers marked on a stage height recurrence intervalplot for each of the catchments of this study. Fivesamplers are installed at each site. At the site, theheight at which each of the samplers takes a sample hasbeen determined accurately using a dumpy level frommarked stream gauge heights. By use of a rating curve,instantaneous streamflow at the time of sampling canbe determined and this data used to calculate pollutantloads.

Figure 3: Stage height recurrence interval plots. Theheight of individual samplers are marked on the plots

and labelled with their corresponding sampler number.Gauge numbers correspond to sites in Figure 1.

Unfortunately siphon samplers do not collect watersamples when the stream stage is decreasing andtherefore manual samples are required for analysis ofthe water quality during this period. Decreases in stage,however, are generally more protracted than increasesin stage and can be adequately manually sampled(Graczyk et al., 2000). A simple comparison of thewater quality data collected by mechanical automaticsamplers and siphon samplers was made in the study ofGraczyk et al. (2000). No systematic biases are evidentin the comparison of data and the methods of that studysuggests that variation in samples were predominantlydue to timing of siphon and mechanical sampling.

A prototype of the sampler has been trialedsuccessfully in the Sullivans Creek catchment of theACT for a runoff event (see Figure 4). Lessons fromthe experience in the Sullivans Creek have led to somedesign modifications for Australian conditions and thesampling program presented here. These include:! increasing the length of the intake loop to 150mm

to increase the depth at which the sample is taken;this also has the desirable effect of decreasing thesample collection time resulting from the greaterhydraulic head;

! securing the intake loop for a better estimation ofthe height at which a sample is taken thus reducingerrors in corresponding estimation of streamflow;

! increasing the size of the collection bottle to 1L toallow a greater range of attributes to be analysed;

! adding a screw cap and coupling at each end tostrengthen the unit and allow ease of access;

! strengthening of the intake and exhaust tubeconnections; and

! painting of the body of the sampler to protect fromultraviolet light deterioration and to assist inconcealment.

Figure 4: Sample collected by the siphon samplerprototype in Sullivans Creek ACT following astreamflow event.

Figure 5: A siphon sampler (with modifications)secured in-stream adjacent to stream gauge marking(Gudgenby River at Nass).

5. RESULTS OF SAMPLINGThe samplers have been positioned in-stream sinceearly March 2001; in this time there have been nosignificant streamflow events. As noted previously, theprototype sampler has successfully collected a singlesample. Analysis of results for any events that occurprior to the Healthy Streams Conference (late August2001) will be included in the associated conferenceposter.

6. DISCUSSIONThe alternate program described in this paper ispresented to stimulate improved methods of waterquality sampling. The cost and importance of theseprograms necessitates that good quality data iscollected, for the appropriate purposes, at theappropriate sites, over a sufficient range ofhydrological conditions.

The alternate program presented here is a step towardsbetter water quality sampling. The salient features ofthe program presented are:! data are collected with a specified objective;! sampling sites have been selected to achieve the

objective of the program;! rising stage samples are collected automatically;

! samples that are to be collected will be of use; and! the program is cost effective.A shortcoming of the alternate program is that fallingstage water quality samples need to be collectedmanually. Research into the design of cost effective,simple falling samplers is continuing. The limitations todesigning these devices are that they require a doubletrigger to start sample collection; they must be robustenough to be deployed in stream for long periods; theymust be simple to construct from readily availablematerials; and they must be inexpensive to produce.The variability of the Australian climate has beendemonstrated in this study. To date no samples havebeen collected in the study catchments. This illustratesthat samples collected as part of a routine program overthis period would give information over only a verynarrow range of hydrologic conditions. The implicationis that there would be a high level of uncertainty inloads estimated from this routinely sampled data.The only sample that has been collected as part of thisstudy has been by the design prototype in a non-studycatchment. The collection of that sample resulted inimprovements to the design of the sampler that hasmade it more robust and reliable for installation in thefield. Further improvements to the design of thesampler will stem from experience in the newcatchments studied.

7. CONCLUSIONWater quality programs are necessary for thequantification of stream health and to improve researchand extend our understanding of riparian systems andlandscapes. However, programs presently in place inthe upper Murrumbidgee catchment are not deliveringresults commensurate with investment. It is suspectedthat this may be the case over much of Australia.This paper has described an alternate approach to thecollection of water quality samples that attempts toovercome some of the design inadequacies of existingprograms. It is hoped that through presentation of thispaper that alternate approaches are sought for waterquality collection within the Murrumbidgee Rivercatchment and more broadly.

8. REFERENCESCroke, B.F.W. and Jakeman, A.J. (2001). “Predictions

in Catchment Hydrology: An AustralianPerspective”. Marine and Freshwater Research,52: 65-79.

Graczyk, D.J., Robertson, D.M., Rose, W.J. andSteuer, J.J. (2000). “Comparison of Water-Quality Samples Collected by Siphon Samplersand Automatic Samplers in Wisconsin”. UnitedStates Geological Survey Fact Sheet, FS-067-00.

Letcher, R.A., Jakeman, A.J., Merritt, W.S., McKee,L.J., Eyre, B.D. and Baginska, B. (1999). Reviewof Techniques to Estimate Catchment Exports,Environment Protection Authority, Sydney.

Murrumbidgee Catchment Management Committee.(1998). Murrumbidgee Catchment Action Plan forIntegrated Natural Resources Management,Wagga Wagga.

Newham, L.T.H., Prosser, I.P., Norton, J.P., Croke,B.F.W. and Jakeman, A.J. (in prep). “Techniquesfor Assessing the Performance of a Landscape-Based Sediment Source and Transport Model:Physical Methods and Model SensitivityAnalysis”, MODSIM 2001, InternationalCongress on Modelling and Simulation, Canberra.

Prosser, I.P., Young, W., Pickup, G., Moran, C. andRustomji, P. (in prep). Predictions of theSediment Regime of Australian Rivers, MODSIM2001, International Congress on Modelling andSimulation, Canberra.

Robertson, D.M. and Roerish, E.D. (1999). Influenceof Various Water Quality Sampling Strategies onLoad Estimation for Small Streams. WaterResources Research, 35(12): 3747-3759.

Sanders, T.G., Ward, R.C., Loftis, J.C., Steele, T.D.,Adrian, D.D. and Yevjevich, Y. (1983). Design ofNetworks for Monitoring Water Quality. WaterResources Publications, Littleton, Colorado,USA.