preliminary nutrient guidelines for victorian inland streams · strategy. a major part of the...

PRELIMINARY NUTRIENT GUIDELINES FORVICTORIAN INLAND STREAMS

Publication 478 June 1995

PRELIMINARY NUTRIENT GUIDELINES FORVICTORIAN INLAND STREAMS

David Tiller and Peter Newall

Catchment and Marine Studies

Environment Protection AuthorityGovernment of Victoria

June 1995

PRELIMINARY NUTRIENT GUIDELINES FOR VICTORIAN INLAND STREAMS

Catchment and Marine Studies

Environment Protection AuthorityOlderfleet Buildings477 Collins StreetMelbourne Victoria 3000Australia

June 1995

ISBN 0 7306 2839 6

iii

FOREWORD

The community is becoming increasingly aware and concerned with the problems of nutrientenrichment of water bodies, and the influence of high nutrient concentrations in supportingundesirable algal blooms.

In response to this concern the Victorian Government has developed a Nutrient ManagementStrategy. A major part of the strategy involves the implementation of Catchment NutrientManagement Plans (CNMPs), which will focus on the rehabilitation of water catchments and streamsthat have been degraded through poor land management, excessive land clearance, and poor streammanagement.

An important step in the development of CNMPs is the establishment of nutrient targets. This reportoutlines preliminary guidelines for phosphorus and nitrogen concentrations in Victorian inlandstreams to assist in the development of CNMPs and to aid in the protection of the aquaticenvironment.

Preliminary guidelines have been determined for seven river regions across the State with similarenvironmental attributes and stream systems. Within each river region, pertinent available biologicaland nutrient data were collated allowing an assessment of background, threshold and "major impact"nutrient concentrations.

During the preparation of these guidelines, deficiencies in knowledge on stream ecosystem responsesto nutrients for several regions in Victoria were highlighted. There is clearly a need for additionalresearch to further our knowledge.

As such, these guidelines must be viewed as preliminary. It is expected that their publication willstimulate input and discussion from interested parties. Following this feedback, and any subsequentrevision, the guidelines will provide, where appropriate, input into CNMPs and State environmentprotection policies.

BRIAN ROBINSONCHAIRMAN

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ACKNOWLEDGEMENTS

The authors thank the following people for their reading, comments and re-reading of thedrafts of this report: from EPA's Catchment and Marine Studies Unit, all Freshwater Studiesstaff, Chris Bell and Lisa Dixon; Rohan Ash, Greg Creek, Phillip Johnstone, CarstenOsmers and Greg Sheehan (EPA); and Peter Vollebergh from the Water ResourcesManagement Branch of the Department of Conservation and Natural Resources.

CONTENTS

FOREWORD .............................................................................................................................. iii

ACKNOWLEDGEMENTS........................................................................................................ v

1. INTRODUCTION ....................................................................................................... 11.1 Background .......................................................................................... 11.2 Scope ................................................................................................... 11.3 Aims..................................................................................................... 2

2. APPROACH................................................................................................................ 32.1 Introduction.......................................................................................... 32.2 Information Sources ............................................................................. 32.3 The River Regions................................................................................ 3

2.3.1 Highlands River Region ......................................................... 42.3.2 Murray Foothills River Region............................................... 42.3.3 Murray Plains River Region ................................................... 42.3.4 Southern and Isolated Foothills River Region......................... 42.3.5 Northwest Plains River Region............................................... 52.3.6 Southwest River Region ......................................................... 52.3.7 Southern Lowlands and Urban River Region.......................... 5

3. HOW TO USE THE GUIDELINES............................................................................. 93.1 Guideline Concentrations ..................................................................... 93.2 Current Nutrient Concentrations Versus the Guidelines ........................ 93.3 Flows ................................................................................................... 93.4 Geographical Precision of the Regions and Guidelines ......................... 10

4. THE NUTRIENT GUIDELINES................................................................................. 114.1 Highlands River Region ....................................................................... 114.2 Murray Foothills River Region ............................................................. 124.3 Murray Plains River Region ................................................................. 134.4 Southern and Isolated Foothills River Region ....................................... 144.5 Northwest Plains River Region............................................................. 154.6 Southwest River Region ....................................................................... 164.7 Southern Lowland and Urban River Region.......................................... 17

5. CONCLUSIONS.......................................................................................................... 20

6. REFERENCES CITED................................................................................................ 23

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1. INTRODUCTION

1.1 Background

Nutrient concentrations in most surface water bodies across Victoria have increased through humanactivities that have created a variety of diffuse and point source inputs (Department of WaterResources 1989). Elevated nutrient concentrations are often cited as contributing to nuisance plantgrowths and associated water quality problems. This has led to several programs, strategies,publications and reports aimed towards developing nutrient criteria or guidelines for inland waters(e.g. ANZECC 1992; Bowles 1982). These undertakings either recognise the individuality of eachwater body and its consequent need for individually assigned criteria, or else provide a very broadrange of values which will cover most water types and situations.

Although all water bodies are individual, catchment managers seeking a specific target for nutrientconcentrations need to be provided with guideline values. These targets cannot be assignedindividually to every water body within Victoria. A more practical method involves the grouping ofwater bodies with similar environmental characteristics and assigning guidelines which reflect thesecharacteristics.

Many important environmental influences upon water bodies - such as climate, soils, topography andland use - are readily delineated at a regional scale. This enables allocation of water bodies intoregional groups and subsequent preparation of nutrient guidelines for those regions. This approachprovides a useful starting point, allowing regional or individual refinement of guidelines for streamsas more data are gathered.

The immediate impetus for the preparation of this document has come from the Nutrient ManagementStrategy for Victorian Inland Waters (Government of Victoria, 1995). A core component of theStrategy is the role of local and regional communities in the co-ordinated management of catchments,including the preparation of Catchment Nutrient Management Plans (CNMPs). The preparation ofCNMPs will be greatly assisted by the provision of achievable yet ecologically meaningful nutrientguidelines. Provision of guideline concentrations for use in the preparation of CNMPs is anEnvironment Protection Authority responsibility (Government of Victoria 1995).

1.2 Scope

Nutrient guidelines ultimately focus attention on the management of point source and non-pointsource nutrient inputs to receiving waters. Nutrient management forms part of a larger goal ofmaintaining or restoring water quality which reflects ecological integrity and sustainability. Theguidelines are therefore based on this ecological goal.

High nutrient concentrations are only one of the problems facing catchment managers. Attainment ofnutrient guidelines may not ensure protection or restoration of aquatic ecosystems. Therefore,nutrient management should be seen as one part of an overall catchment management strategy.

The nutrient guidelines have been limited to rivers and streams, due to a lack of useable informationof lakes and impoundments in Victoria. In addition, impoundments are typically managed for watersupply or hydro electricity, with ecological integrity being compromised. Although lakes andimpoundments are not the subject of this document, there is a need to consider the setting of nutrientguidelines for these water bodies. Many of Victoria's lakes are, however, grossly nutrient enriched.For example, nutrient concentrations in Lake Colangulac resemble those in secondary treated sewageeffluent (Metzeling et al. 1993a). Many lakes are terminal systems, and adding nutrients can have

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very long term consequences. To prevent problems due to nutrient enrichment it is evident that inputof nutrient rich effluents should not be occurring, and that considerable effort should be put intocontrolling nutrients originating from non-point source discharges, including irrigation return wastewaters.

The nutrient status of water bodies is usually determined by either estimating total loads, orcharacterising concentrations. Concentrations provide a measure of the immediate availability ofnutrients to algae and other plants. Nutrient loads are more applicable to endpoints, such as lakes andreservoirs, where nutrients tend to accumulate and sediments can be a major source of nutrients to thewater column. The intended use of these guidelines for community based projects necessitates theirpresentation in a form which is readily understandable, able to be monitored, and easily related tostream ecosystem effects, in particular algae and other plant growth. These guidelines are thereforeprovided as concentrations rather than loads.

This report is intended to be a working document which will stimulate discussion and on-goingrefinement of nutrient guidelines. The report covers the two major nutrients - nitrogen andphosphorus - and provides preliminary nutrient guidelines to assist in the maintenance and protectionof river and stream ecosystems.

Guidelines for total nitrogen and total phosphorus are provided even though these are likely to be anoverestimate of nutrient bioavailability. Nonetheless, there is little agreement on what is bioavailableand how it is measured, making meaningful estimates of bioavailability difficult. In addition, thereare complex and potentially rapid transformations between the forms of these nutrients, adding furtherdifficulties.

Nitrogen to phosphorus ratios are not used in the guidelines. There is a lack of consensus on the useof nitrogen to phosphorus ratios, in particular the critical ratios, and the forms of nitrogen andphosphorus to use. A particularly useful critique of nitrogen to phosphorus ratios can be found in theAustralian Water Quality Guidelines for Fresh and Marine Waters (ANZECC 1992).

1.3 Aims

The major aims of this report are:

• to divide Victoria into river regions, within which the majority of rivers and streams aresufficiently similar to allow the allocation of nutrient guidelines (as described below);

• to provide preliminary, quantitative nutrient guidelines for inland rivers and streams for eachregion;

• to identify and highlight priority streams and regions for further study.

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2. APPROACH

2.1 Introduction

The development of nutrient guidelines, as with the development of any water quality guideline,criterion or standard, must take into consideration a vast array of physical, chemical and biologicalfactors. The first aim required the delineation of regions despite the wide range of aquaticenvironments and conditions to be characterised.

The second aim required the assignment of guidelines despite limited information. This includedinformation on the influence of factors other than nutrients on algae and other plants growth. In lakesand impoundments, light, temperature, and the forms and bioavailability of nutrients, have a majorrole in algal blooms (Government of Victoria, in prep; Johnstone 1994). These factors are alsoimportant for plant growth in running waters, as are stream flow and substrata. If any of these factorsare unfavourable to plant growth then high nutrient concentrations may not be accompanied by highplant biomass - so an absence of nuisance plant growths does not necessarily mean that nutrientconcentrations are at acceptable levels. Measures of these factors are not included in the nutrientguidelines, but their potential impact on plant growth needs to be taken into account when assessingthe likely impacts of nutrient reductions. Nevertheless, reasonably reliable assumptions concerningthe influence of many of these factors could be made, and the guidelines which result should berelatively robust.

2.2 Information Sources

These preliminary guidelines are primarily based on studies from south eastern Australia in whichwater quality was measured concurrently with biological sampling. Although this report was initiateddue to concerns about excessive plant growths, the allocation of nutrient guidelines for maintenanceof aquatic ecosystem integrity must also include consideration of fauna - particularly since many ofthe ecological studies involving responses to nutrient additions are zoological in nature. Increasednutrients have been demonstrated to increase populations of invertebrate fauna through higher plantproduction which provides substrate, shelter and food for the fauna (Gregory 1983; Cheal et al. 1993;Biggs and Lowe 1994). Additionally, some taxa are adversely affected by high nutrientconcentrations (Cheal et al. 1993), enhancing their value in water quality studies. Accordingly,invertebrate studies were used where they gave an indication of nutrient status or perturbation as aresult of nutrient additions. The use of biota in assessment is a key feature of the guidelines, allowingthe formulation of ecologically derived values.

In regions where there are insufficient studies incorporating biota and nutrients, data from long termwater quality monitoring has been combined with available biological information to allow a tentativeassessment of nutrient effects within the region. The resultant guidelines were prepared followingexamination of reports, data and other information.

2.3 The River Regions

River regions used in this report are delineated using a combination of the ecoregion concept(Omernik 1987) and river tracts (Land Conservation Council 1989). Ecoregions proposed byOmernik (1987) for the United States were based on climate, soils, physiography, and potentialnatural vegetation, with the often overlapping nature of these features assisting the allocation ofboundaries. In this study, river region boundaries are separated on the basis of topography, runoff,and tract type (ranges, foothills, valleys, plains). In contrast to the more objective methods used byOmernik (1987) for delineating ecoregions, river regions in this report are partially defined usingsubjective assessment and local knowledge of the areas. Seven river regions are identified (Figure 1).

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2.3.1 Highlands River RegionAltitude is the primary feature delineating this region. Most of the areas in Victoria above 1000m arewithin the Highlands River Region, which is generally minimally disturbed and predominantlyforested. The region also includes all the alpine areas in Victoria. Median annual runoff in the regionvaries from below 125 mm to above 1000 mm (Holmes 1982). Major forest types range from tallopen forest to open forest (Carnahan 1990). Streams in this region are typically very shallow withclear water, turbulent flows and a rocky substrate. Many streams occur as spring and wetland outlets,and are generally less than four metres wide, although there are substantially wider rivers within theregion. The alpine streams tend to have open vegetation around the banks, whereas at lower altitudesthe banks tend to be densely forested.

Catchments of headwater streams of the Upper Murray, Kiewa, Ovens, Goulburn, Yarra, Thomson,Mitchell, Tambo, Snowy and - to a very small extent - the LaTrobe Rivers catchments combine toform this region. Within the region are all the alpine ski resorts, including Falls Creek, Mt Hothamand Mt. Buller.

2.3.2 Murray Foothills River RegionThis region is delineated as part of the eastern Victorian uplands with moderate relief and drainage tothe north of the Great Dividing Range. Most of the region has an annual median runoff between 50and 125 mm, with the lower values being in the north and western areas (Holmes 1982). The UpperMurray, the Kiewa, Ovens and Goulburn Rivers all flow through the Murray River Foothills, afteroriginating in the Highlands. The Broken, Campaspe and Loddon River catchments all originate inthe Murray River Foothills. Towns within the region include Corryong, Bright, Yea, Kyneton, andDaylesford. Mt Beauty, in the Kiewa River Catchment, lies near the boundary between this riverregion and the Highlands River Region.

Before European settlement, much of the region was covered with vegetation ranging from openforest to woodland (Carnahan 1990). Currently, most of the area is under pasture following majorwoodland clearance (Carnahan 1990, Webb 1982). In their natural state the rivers of this region aretypically five or more metres wide, more than 30 cm deep and have clear waters. The streams havepool and riffle sequences and - unless cleared - well shaded banks. Flows are generally moderatelyfast and bed material is typically rock and gravel.

2.3.3 Murray Plains River RegionOccupying the north east to north-central part of the state, the catchments in this region also drain tothe Murray River, and receive waters from the Murray Foothills and - to a lesser extent - theHighlands River Regions. The region includes a small portion of the Kiewa Catchment, the lowerportions of the Ovens and Goulburn catchments, and most of the Broken, Campaspe and Loddoncatchments. Towns which typify the region include Echuca, Shepparton, and Wangaratta. Wodongaand Bendigo lie near the boundary of the Murray Plains and Murray Foothills River Regions.Delineation of the region was based primarily on its low relief (generally below 200 m) and its lowmedian annual runoff of less than 25 mm (Holmes 1982).

Prior to European settlement most of the region was covered by woodland and low woodlandvegetation. Much of the region has been cleared and contains sown pasture, croplands, and tussockgrasslands (Carnahan 1990). As well as containing dryland agriculture, much of the region isirrigated. The rivers of the region can be typified as turbid, moderately deep and clay-bottomed, withwell shaded banks unless cleared.

2.3.4 Southern and Isolated Foothills River RegionThe Southern Foothills comprise the lower relief areas of the Victorian uplands that drain southward.These extend westward from the East Gippsland catchments through to the uppermost reaches of theHopkins Catchment. The Isolated Foothills component of the region consist of the Grampians, the

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Otway Ranges, the Strzelecki Ranges, and Wilsons Promontory. Towns within the Southern Foothillsinclude Cann River, Buchan, Licola, Aberfeldy and Ballarat. Towns within the Isolated Foothillsinclude Mirboo North, Tidal River, Gellibrand and Halls Gap which occur in the Strzelecki Ranges,Wilsons Promontory, the Otway Ranges and the Grampians respectively.

For much of the Southern and Isolated Foothills, the median annual runoff is between 50 and 125mm, exceeding 125 mm at Wilsons Promontory, 250 mm in parts of the Grampians, 500 mm in theStrzelecki Ranges, and 750 mm in the Otway Ranges. Most of the region's natural vegetation coverwas medium open forest, with patches of tall open forest in the Strzelecki Ranges and the OtwayRanges, and low open forest in the Grampians (Carnahan 1990). The current vegetation cover of theregion includes some largely undisturbed forests in the eastern southern foothills, as well as areassubjected to forestry operations, including clear felling. Further west there are large areas of pastureand croplands (Webb 1982).

Rivers within the region have some similar characteristics to those of the Murray Foothills, beingtypically wider than 5 m, exceeding 30 cm depth, having clear waters and pool and riffle sections.Many of the streams of the region are rocky bottomed with smooth rounded cobbles and bouldersforming the stream bed.

2.3.5 Northwest Plains River RegionThe majority of the catchments of the Avon, Richardson, Avoca and Wimmera Rivers form this riverregion, which is typically low elevation, and formed on sandy, coastal and alluvial plains and dunefields (Jenkin 1982). Median annual runoff is below 10 mm for most of the region (Holmes 1982).Towns within this region include Horsham, Dimboola, Donald and Charlton.

Prior to European settlement, most of the vegetation of the region consisted of open scrub, openshrubland and tall open shrubland, with areas of tussock grassland (Carnahan 1990). Currently, mostof the region is under cropping and dry land grazing (Wilson 1994). The streams of the NorthwestPlains River Region form closed drainage networks that tend to run into terminal lakes. They aregenerally intermittent and saline, often forming a chain of interconnected pools which are moretypical of lakes than streams, except during high flow events.

2.3.6 Southwest River RegionMost of the Southwest River Region consists of basaltic lava plains and Quaternary coastal plains(Jenkin 1982), across the Corangamite, Hopkins, Portland, and Glenelg catchments. Median annualrunoff in the eastern half of the region is typically between 10 and 50 mm, and between 50 and 125mm in the western half (Holmes 1982). The natural vegetation of the region was predominantlywoodland and open woodland, with areas of tussock grassland and low open forest (Carnahan 1990).Today, most of the region is cropland and grassland, with areas of open woodland and very openwoodland (Paine 1982). Towns within the region include Hamilton, Colac, Casterton andCamperdown.

Rivers of the region are typically perennial, although some are intermittent. Most have rocky/gravellybeds and are dominated by macrophytes. Many have high salinities. Generally, streamsidevegetation has been removed and the waters are often slightly turbid and often coloured.

2.3.7 Southern Lowlands and Urban River RegionIn contrast to the other river regions, this region is largely delineated by human influences. Thecatchments in this region contain the substantial portion of Victoria's population and industry, andincludes greater Melbourne, Geelong and the LaTrobe Valley. The remainder is mostly underintensive agriculture.

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Although on the basis of physiographic features (Jenkin 1982), the region could be divided into two,with the area west of the Yarra catchment incorporated into the Southwest River Region and theremainder forming a Yarra and Gippsland Plain River Region, this region is defined on purely humaninfluences. Delineation on the basis of human influences also results in difficulties in typifying theregion and its rivers in terms of other natural features. Median annual runoff ranges from less than 25mm to greater than 250 mm. Natural vegetation is very diverse, ranging from tall open forests,through open woodlands, to tussock grasslands (Carnahan 1990).

The streams in this region are typically the most disturbed and modified in the State, and include themiddle and lower Yarra, Maribyrnong, Werribee, and Moorabool catchments, all but the uppermostportions of the Barwon, LaTrobe and South Gippsland catchments, and the entire Bunyip catchment.The lowland rivers of the region are typically slow flowing, turbid, clay/mud bottomed andmoderately deep. Tributaries to these are often deeply incised, channelised, contain litter, and havehigh but short duration peak flows. Many of the urban streams have high concentrations of nutrients,heavy metals and petroleum hydrocarbons.

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(Figure 1: Victorian River Regions)

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3. HOW TO USE THE GUIDELINES

3.1 Guideline Concentrations

Background concentrations in this reportare those which would be expected for undisturbed streamsin a given river region. Threshold concentrations are the estimated maxima above which damage tothe ecological community will occur. The threshold concentrations are therefore the guidelinemaxima concentrations recommended for the restoration or maintenance of the aquatic ecosystemswithin a river region. The nutrient concentrations described as "major impact" concentrations in thisreport are those at which gross disturbance of the aquatic ecosystem could be expected.

3.2 Current Nutrient Concentrations Versus the Guidelines

It is intended that the provision of nutrient guidelines will assist catchment managers in the restorationof degraded streams, or the maintenance of healthy streams. Streams or stream reaches which havehigher than recommended nutrient concentrations should be managed with the aim of reducingnutrient concentrations to within the recommended values.

The guidelines are not ecological optima, rather they are threshold levels beyond which markedecosystem degradation has been observed. Therefore, in streams where nutrient concentrations arebelow the guideline levels, it is not acceptable to increase nutrient concentrations up to the guidelines,and the aim should be to at least maintain current concentrations.

3.3 Flows

An important feature of these guidelines is that they are designed for base flow conditions. Duringbase flow conditions, any excess of nutrients has potential to contribute to excessive plant growthsand a resultant ecosystem disturbance. The guidelines are not median or percentile values, and shouldnot be exceeded at any time during base flow conditions.

Notwithstanding the above, it is recognised that dissolved and suspended sediment loads increasegreatly during high flow periods, and that the nutrients contributed during these events will add toecosystem stress. Indeed, the bulk of a stream's total nutrient load is transported during theseinfrequent, high flow events. However, from a monitoring perspective, high flow events arecomparatively rare, and nutrient concentrations during these events are strongly influenced by themagnitude of the high flow, which period of the high flow is sampled (accession versus recession),rainfall intensity, and which part of the catchment receives the rainfall. For practical purposes it istherefore more useful to set guidelines for baseflow conditions, which are more stable and generallyprevail.

Many streams in the State are commonly dry. Intermittent streams flow only seasonally, whilestreams that are generally dry and have unpredictable flows are called episodic. Intermittent andepisodic streams are very common in Victoria, particularly in the north. Little is known about thesestreams, although the limited data available indicate that they contain a rich aquatic fauna whensurface water is present (Boulton and Suter 1986, Brooks and Boulton 1991). The fate, behaviour andeffects of pollutants in these streams is virtually unknown. Perennial streams on the other hand arereasonably well understood, and our understanding of intermittent and episodic streams is,unfortunately, based on concepts mostly derived from perennial streams. However, the impact ofpollutants discharged to non-flowing streams is likely to be substantially greater than that experiencedby perennial streams (Boulton and Suter 1986) and consequently, effluent discharges should not occurto streams during periods of non-flow. The guidelines should otherwise apply to these streams.

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3.4 Geographical Precision of the Regions and Guidelines

Placing every river and stream within the state into one of seven geographical groups is clearly goingto result in exceptions. Similarly, the boundary between two adjacent river regions will necessarily bebroad. In situations where there are clear exceptions, or where a stream reach is close to a regionalboundary, there will clearly be a need for specific assessment by the catchment manager. Theseguidelines therefore provide regional values, against which individual stream nutrient objectives canbe set.

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4. THE NUTRIENT GUIDELINES

4.1 Highlands River Region

An intensive study of the invertebrate communities of the Thredbo River (altitude greater than 1,200m) in Kosciusko National Park, NSW, found a substantial impact resulting from a sewage effluentdischarge (Tiller 1988), which thereafter diminished with distance downstream. The results from thatstudy suggested that the threshold concentrations at which no community disturbance was detected,were 0.020 mg L-1 for total phosphorus and 0.150 mg L-1 for total nitrogen. These findings areconsistent with those of Cullen (1983), who found no biostimulation of attached filamentous algae inthe Crackenback (Thredbo) River with a phosphorus concentration of 0.020 to 0.025 mg L-1 andnitrogen concentrations typically below 0.150 mg L-1, and obvious biostimulation with a phosphorusconcentration of 0.050 mg L-1 and a nitrogen concentration of 0.360 mg L-1. The background andthreshold nutrient concentrations, and the concentrations at which substantial impacts were observedare displayed in Table 4.1.

Table 4.1: Background, threshold and major impact nutrientconcentrations (mg L-1) in the Thredbo River.

Total Phosphorus Total NitrogenBackground 0.010 0.070Threshold 0.020 0.150Major Impact 0.050 0.250

Background total phosphorus concentrations reported by Tiller (1988) are similar to those reported byMorley et al. (1989), who found healthy aquatic communities in Mt Stirling streams with median totalphosphorus concentrations ranging from 0.010 to 0.014 mg L-1 across six sites. Although onlynitrate/nitrite was recorded for the Mt. Stirling study, median concentrations ranged from 0.008 to0.048 mg L-1 across the six sites.

Based on the above information, the preliminary nutrient guideline maxima recommended for the Highlands River Region are:

Total Phosphorus: 0.020 mg L-1

Total Nitrogen: 0.150 mg L-1

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4.2 Murray Foothills River Region

Metzeling and McKenzie-Smith (in prep) examined invertebrate community response to fish farmeffluent of differing nutrient concentrations entering three streams in the Goulburn catchment - theMurrindindi and Rubicon Rivers, and Snobs Creek. These data showed healthy invertebratecommunities at sites upstream of the effluent discharges, where total phosphorus concentrations weregenerally in the range of 0.010 to 0.020 mg L-1, and total nitrogen concentrations were up to 0.200 mgL-1.The study also monitored sites at increasing distances downstream from the effluent discharges, withconsequent dilution of the nutrients. At concentrations of 0.090 mg L-1 total phosphorus and 0.600mg L-1 total nitrogen, the invertebrate community was clearly disturbed. Between 0.050 and 0.090mg L-1 total phosphorus, and 0.400 to 0.500 mg L-1 total nitrogen, the biota appeared healthier, yetstill disturbed, and had not recovered until total phosphorus concentrations were approximately 0.030mgL-1 and total nitrogen was less than 0.200 mg L-1. The background and threshold nutrientconcentrations, and the concentrations at which substantial impacts were observed are displayed inTable 4.2.

Table 4.2: Background, threshold and major impact nutrientconcentrations (mg L-1) in the upper Goulburn catchment.

Total Phosphorus Total NitrogenBackground 0.010-0.020 0.100-0.200Threshold 0.030 0.200Major Impact 0.050 0.400

Support for the background concentrations is provided by long term physico-chemical data for theOvens River at Bright. From 35 samples collected between 1975 and 1987, median total phosphorusconcentrations were 0.017 mg L-1 and median total nitrogen concentrations were 0.300 mg L-1 (RuralWater Commission 1990). From 12 samples collected in 1993, the median total phosphorusconcentration was 0.016 mg L-1 and the median total nitrogen concentration was 0.140 mg L-1

(Hunter and Zampatti 1994b). The invertebrate fauna at this site was found to be indicative of ahealthy stream (EPA unpublished data).

Based on the above information, the preliminary nutrient guideline maximarecommended for the Murray Foothills River Region are:



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4.3 Murray Plains River Region

In the lower Goulburn River nutrient concentrations steadily increase from downstream of thediversion weir at Nagambie to the confluence with the River Murray (from 0.030 to 0.100 mg L-1

total phosphorus, and 0.300 to 1.000 mg L-1 total nitrogen) (Tiller and Bate in prep). The invertebratecommunities, however, vary surprisingly little compared to the changes that occur in foothills areaswith similar nutrient increases. The invertebrate communities in lowland reaches of the Ovens andCampaspe Rivers also had a similar fauna to the lower Goulburn River (EPA unpublished data), eventhough nutrient concentration varied substantially (Table 4.3). The lowland reaches of the RiverMurray tributaries generally have high suspended solids, substantially reducing light penetration, thuslessening the potential for most planktonic and submerged plant growth. The influence of nutrientson plant and invertebrate communities is, therefore, likely to be limited.

Cyanobacteria and some algae, including diatoms, can alter their buoyancy and hence overcome highturbidity (Wetzel 1983). Mycrocystis sp. (Cyanobacterium) and Melosira (diatom) blooms haverecently been observed in the lower reaches of the lower Goulburn River. Total phosphorusconcentrations in this reach measured during a bloom were between 0.110 and 0.120 mg L-1 and totalnitrogen between 0.700 and 1.000 mg L-1. It is not uncommon for phosphorus and nitrogen to remainat these levels even during prolonged periods of low flow. In contrast to the lower Goulburn, nutrientconcentrations in the lower reaches of the Ovens River are substantially lower (Table 4.3), and algalblooms have not been reported during similar low flow periods. The Ovens River can, for allpractical purposes, be considered near background nutrient status. The background and thresholdnutrient concentrations, and the concentrations at which substantial impacts were observed aredisplayed in Table 4.4.

In addition to nutrients, current velocity and turbidity are major factors in the formation of blooms. Itis likely that in the lower Loddon River, the lower reaches of the lower Goulburn River and possiblythe Campaspe River, nutrients are always in excess, and blooms are limited by light penetration andflows. During prolonged low flow periods where water clarity increases and turbulence does notnegate cell buoyancy, streams with nutrient concentrations above the recommended guidelines are atrisk of developing nuisance blooms. Sediments may also be a major potential source of nutrients inslow flowing lowland rivers. Their importance is unknown.

Table 4.3. Total phosphorus and total nitrogen concentrations (mg L-1) for several rivers in theMurray Plains River Region.

River Site Total phosphorus Total nitrogen Suspended solidsOvens Peechelba 0.044 0.440 24Goulburn McCoys 0.120 1.010 50Goulburn Undera Nth 0.090* 0.700* -Goulburn Murchison/Arcadia 0.025* 0.300* 16**

Campaspe Rochester 0.073 1.210 27Loddon Appin 0.100 1.300 70

All data from long term median, EPA Water quality Network unpublished data, except; * fromTiller and Bate in prep., and ** Hunter (1993)

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Table 4.4: Background, threshold and major impact nutrient concentrations (mg L-1)in Murray Plains rivers during low flow periods.

Total Phosphorus Total NitrogenBackground 0.025-0.045 0.300-0.500Threshold 0.050-0.070* 0.500-0.600*Major Impact 0.120 1.000

*insufficient data to determine threshold concentrations more accurately

There are limited studies where nutrient and biological sampling have occurred concurrently in thisregion. This limitation is underscored by the occurrence of severe blooms in streams within theregion. The Murray Plains River Region is therefore a high priority region for concurrent nutrient andbiological studies. The occurrence of occasional planktonic blooms suggests that monitoring of thephytoplankton is also needed. Design of monitoring programs should include both long term, lowintensity sampling and more intensive sampling during times of high bloom risk.

Based on the above information, the preliminary nutrient guideline maxima recommended forthe Murray Plains River Region are:



4.4 Southern and Isolated Foothills River Region

Water quality data which are available indicate that the forested catchment ecosystems of this riverregion are of similar (high) quality to the forested catchment streams in the Murray Foothills RiverRegion (Marchant et al. 1985; Hunter and Zampatti 1994b and EPA unpublished data). Althoughthese streams drain to the coast rather than the Murray River, the similarity in altitude,geomorphology, land cover and available water quality data, suggests that, pending further studies, itis reasonable to use the Murray Foothills River Region guidelines for the Southern and IsolatedFoothills River Region.

Some background water quality data from streams within this river region are supplied in Table 4.5.This table provides background nutrient data from sites without major disturbance and includes fivesites from southern foothills and two sites from isolated foothills (Upper Gellibrand in the OtwayRanges, and Big Cord in the Grampians).

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Table 4.5: Median total phosphorus and total nitrogen concentrations (mg L-1) for severalrivers in the Southern and Isolated Foothills River Region

River Site Total Phosphorus Total NitrogenBemm Princes Hwy 0.011 0.365Buchan Buchan 0.011 0.226Timbarra d/s Wilkinson Ck. 0.016 0.231Mitchell Glenaladale 0.011 0.104Aberfeldy Beardmore 0.007 0.107Macalister Licola 0.007 0.100Gellibrand Upper Gellibrand, Otways 0.021 0.330Glenelg Victoria Vly., Grampians < 0.005 0.300

Source: Hunter and Zampatti (1994b)

There is a shortage of concurrent nutrient and biological assessment of the Southern and IsolatedFoothills River Region. This region should therefore be given high priority to allow confirmation orreassessment of these guidelines.

Based on the above information, including the apparent similarity of this river region to theMurray Foothills, the preliminary nutrient guideline maxima recommended for the Southern

and Isolated Foothills River Region are:



4.5 Northwest Plains River Region

Combined biological and chemical data for the region are restricted to the middle and lowerWimmera River system, which - on the basis of these data - was described as an intermittentlyflowing, turbid, nutrient rich system suffering from a variety of stresses (Metzeling et al. 1993b).Effects of salinity, turbidity, a low flow regime, and potential pesticide contamination during thecourse of the study have confounded any attempts to relate the stream biota to nutrient concentrations.Additionally, no data were collected from a site representative of a background, or low impact, part ofthe region.

Total phosphorus concentrations for many rivers within the region are comparable to backgroundlevels for the Murray Plains River Region (Table 4.6). In contrast, the total nitrogen levels aretypically well in excess of the background concentrations in the Murray Plains River Region.

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Table 4.6: Median total phosphorus and total nitrogen concentrations (mg L-1) for severalrivers in the Northwest Plains River Region.

River Site Total Phosphorus Total NitrogenWimmera Glenorchy 0.030 0.742Wimmera Horsham 0.052 0.931Wimmera Dimboola 0.041 0.909Avon Donald 0.045 0.904Avoca Coonooer 0.057 0.908

Source: Hunter and Zampatti (1994b)

Consideration of acceptable nutrient concentrations for the region is complicated by the extremelyvariable flow and the temporary effects of episodic flows upon nutrient concentrations. During theperiod of sampling by Metzeling et al. (1993b), the only occasions when cyanobacteria exceededapproximately 1000 cells or more per millilitre, were during low flows immediately following largeflow events. Corresponding to the large flow events were temporary massive increases in nutrientconcentrations. At the site downstream of Dimboola (Table 4.6), 1993 median total phosphorusconcentrations were 0.041 mg L-1, and median total nitrogen was 0.909 mg L-1. At the same site acyanobacterial bloom occurred in 1987 following a high flow event and total phosphorus andnitrogen concentrations of 0.500 and 2.000 mg L-1 respectively (Metzeling et al. 1993b).

There is clearly a high priority for studies which examine the relative and combined effects of nutrientconcentrations and flows on the aquatic biota of the Northwest Plains River Region.

Based on the lack of information, a default position of no worsening of current water qualityhas been adopted. Therefore, interim guideline maxima for the Northwest Plains River Region

are:



4.6 Southwest River Region

There are limited water quality and biological data for this region. Recent invertebrate sampling ofsouth west rivers shows that many of the streams had a diverse and abundant fauna (EPA unpublisheddata). Physico-chemical data are available for several locations (Metzeling et al. 1993a; Hunter andZampatti 1994a, 1994b; EPA unpublished data). These data generally show that many of the riversand streams in the southwest are clear, slightly saline, and while moderately low in phosphorus arehigh in nitrogen. The most striking feature of the rivers and streams in the southwest is that theirmacrophyte communities are very diverse and abundant compared to most other rivers and streams inthe State.

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Table 4.7. Median total phosphorus and total nitrogen concentrations (mg L-1) for severalrivers and streams in the Southwest River Region.

River Site Total phosphorus Total nitrogenGlenelg R. Casterton 0.018 0.640Wannon R. Henty 0.035 0.950Hopkins R. Framlingham 0.031 1.370Mt Emu Ck Taroon 0.048 1.100

All data from long term median, EPA unpublished data

Assessment of the guidelines should be given high priority through further studies of the region, andleast impacted sites need to be identified and incorporated into community and nutrient samplingprograms. Concurrent biological and nutrient assessment of point source nutrient inputs may assistthese studies.

Based on the lack of information, a default position of no deterioration of current water qualityhas been adopted. Therefore, interim guideline maxima for the Southwest River Region are:



4.7 Southern Lowland and Urban River Region

This region is almost entirely devoid of natural vegetation cover and, where not used for agriculture,is typically highly urbanised. In addition, the overwhelming proportion of the State's industrialactivity occurs within this region. The predominance of human influences, particularly in the urbanareas, make the assigning of realistic, but attainable, guidelines difficult. In addition, littleinformation on the effects of nutrients on ecosystems is available for rivers and streams in this region,even though it contains the substantial part of the State's population. The data which are availableclearly indicate the generally poor state of water quality and ecosystem health in these rivers andstreams (Table 4.9) (Metzeling et al. 1993a; Reed and Newall 1990; Reed 1992; Mitchell and Clark1991; Pettigrove 1989; Robinson 1988).

For the purpose of setting nutrient objectives, the rivers and streams of the region have been dividedinto three classes:

1. Rural lowland rivers and their tributaries (e.g. Thomson and Macalister Rivers);

2. Larger urban lowland rivers (lower reaches of the Yarra, Maribyrnong, Werribee and BarwonRivers and Dandenong Creek); and,

3. Urban tributary streams (e.g. Merri, Darebin, Mullum Mullum and Olinda Creeks).

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In general, urban lowland rivers tend to have suffered substantial habitat loss and poorer water qualitycompared to rural lowland rivers. Urban lowland rivers also tend to be considerably wider, deeper,slower flowing and much more turbid than the tributaries. Except for substantial habitat loss andremoval of riparian vegetation, the rural lowland rivers and streams have similar flow and waterquality characteristics to Murray Plains rivers (Tables 4.3 and 4.9), suggesting that it is reasonable touse the Murray Plains guidelines for this part of this region. The LaTrobe State EnvironmentProtection Policy (SEPP) has recommended total phosphorus and nitrogen concentrations for theLaTrobe River (Environment Protection Authority 1995). These are based on percentiles and cannotbe directly related to the preliminary guidelines.

For the large urban lowland rivers the objectives should be as for the rest of the Southern LowlandsRiver Region (recommended maxima are 0.050 mg L-1 total phosphorus and 0.600 mg L-1 totalnitrogen). However, at the present time this objective will not be met as nutrient concentrations aregenerally more than twice the objectives (Table 4.10). Total phosphorus and nitrogen concentrationsof 0.080 and 0.900 mg L-1 respectively are suggested as an interim measure only. These objectiveswill still be difficult to meet. In the longer term the recommended maxima for Southern LowlandsRiver Region should replace these interim objectives as they offer the required level of ecosystemprotection.

While altitudes are generally relatively low, the physical characteristics of urban tributaries suggestthat the most appropriate nutrient objectives should approximate that of the Southern and IsolatedFoothills River Region, that is 0.030 mg L-1 total phosphorus and 0.200 mg L-1 total nitrogen. Presentconcentrations are, however, between four and ten times these (Table 4.11). As a first step in nutrientreduction, 0.100 mg L-1 total phosphorus and 1 mg L-1 total nitrogen are proposed as guidelines forthe urban tributaries. Almost all the tributaries will currently fail this objective, but it is not anunrealistic target for nutrient reductions. These guidelines, however, will not lead to significantreduction in algal and other plant production as nutrients remain in excess of requirements. This stepis required to halt further deterioration in the urban tributaries, and will set a trend towards continuingimprovement of stream ecosystems.

Table 4.9: Median total phosphorus and total nitrogen concentrations (mg L-1) for several ruralrivers in the Southern Lowland and Urban River Region.

River Site Total phosphorus Total nitrogenLaTrobe R. Willow Grove 0.038 0.670LaTrobe R. Rosedale 0.091 0.930Yarra R. Launching Place 0.270 0.640Werribee R. u/s Werribee 0.089 1.040Barwon R. Rickets Marsh 0.049 0.630


Table 4.10: Total phosphorus and total nitrogen concentrations (mg L-1) for several urbanrivers in the Southern Lowland and Urban River Region.

River Site Total phosphorus Total nitrogenYarra R. Warrandyte 0.100 1.090Yarra R. Fairfield 0.125 1.240Barwon R. Geelong 0.128 1.240


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Table 4.11: Total phosphorus and total nitrogen concentrations (mg L-1) for several urbantributaries in the Southern Lowland and Urban River Region.

River Site Total phosphorus Total nitrogenPlenty R. Greensborough* 0.300 2.460Merri Ck. Fitzroy* 0.210 1.420Maribyrnong R Sunshine 0.230 0.850Kororoit Ck. Altona 0.695 4.010Dandenong Ck. Dandenong 0.180 2.010

All data from long term median, EPA unpublished data, except * from Hunter and Zampatti 1993b

Due to the extremely high nutrient concentrations in urban rivers and streams research needs to bedirected towards developing nutrient reduction strategies and assessing their effectiveness, rather thanreassessment of the guidelines.

Based on the above information, the preliminary nutrient guideline maxima recommended forthe Southern Lowland and Urban River Region are:

Rural rivers and streams:Total Phosphorus: 0.050 mg L-1


Urban rivers - interim:Total Phosphorus: 0.080 mg L-1


Urban rivers - long term:Total Phosphorus: 0.050 mg L-1


Urban tributaries - interim:Total Phosphorus: 0.100 mg L-1


Urban tributaries- long term:Total Phosphorus: 0.030 mg L-1


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5. CONCLUSIONS

While setting a clear direction and genuine goals, the development of these nutrient guidelines mustbe viewed as dynamic and on-going. The State has been divided into regions defining similarenvironmental attributes likely to influence stream characteristics.

On the basis of currently available information, total phosphorus and total nitrogen maxima have beenascribed to these regions (Figure 2).

Research is required to further develop the guidelines. Highest priority should be given to theNorthwest and Southwest River Regions. The North West River Region is regularly suffering effectsof cyanobacterial blooms and the situation is not likely to improve without an understanding of theimpact of low flows and nutrients combined. The South West River Region rivers are largelyunknown with respect to effects of nutrients.

Concentrations of nutrients in many streams across the State exceed the guidelines. Priority should begiven to nutrient reduction strategies in many of Victoria's rivers and streams, in particular the largelowland rivers and urban streams, which are typically well in excess of their preliminary guidelineconcentrations.

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Figure 2: Preliminary nutrient guidelines for Victoria's river regions.

(Map is being drafted)

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6. REFERENCES CITED

ANZECC (1992). Australian Water Quality Guidelines for Fresh and Marine Waters. Australianand New Zealand Environment and Conservation Council.

Biggs, B. and Lowe, R. (1994). Responses of two trophic levels to patch enrichment along a NewZealand stream continuum. New Zealand Journal of Marine and Freshwater Research 28:119-134.

Boulton, A. and Suter, P. (1986). Ecology of Temporary Streams - an Australian Perspective. In: P.De Deckker and W.D. Williams (Eds.) Limnology in Australia. CSIRO/Dr W Junk.

Bowles, B. (1982). Nutrient Criteria for Inland Waters. Ministry for Conservation EnvironmentalStudies Series, Publication Number 394, Ministry for Conservation, Victoria.

Brooks, S. and Boulton, A. (1991). Recolonization dynamics of benthic macroinvertebrates afterartificial an natural disturbances in an Australian temporary stream. Australian Journal of Marineand Freshwater Research 42, 295-308.

Carnahan, J. (1990). Vegetation, in Atlas of Australian Resources, prepared by Australian Surveyingand Land Information Group, Australian Government Publishing Service.

Cheal, F., Davis, J. and Growns, J. (1993). Relationships between macroinvertebrates andenvironmental variables. In Wetlands of the Swan Coastal Plain, Volume 6. Water Authority ofWestern Australia and Environment Protection Authority, Western Australia.

Cullen, P. (1983). Sewage effluent disposal in the Crackenback River - the assimilation capacity ofan upland stream. Report to Kosciusko Thredbo Pty. Ltd., Canberra.

Department of Water Resources (1989). Water Victoria - A Resource Handbook. Department ofWater Resources, Victoria.

Environment Protection Authority (1995). Draft State Environment Protection Policy (Waters ofVictoria) Schedule F5 - Waters of the LaTrobe and Thompson River Basins and Merriman CreekCatchment and Draft Policy Impact Assessment. Environment Protection Authority, Victoria.

Government of Victoria (1995). Nutrient Management Strategy for Victorian Inland Waters. State ofVictoria

Government of Victoria (in prep). Blue Green Algae and Nutrients in Victoria: A ResourceHandbook. State of Victoria.

Gregory, S. (1983). Plant-herbivore interactions in stream systems, in Stream Ecology: Applicationand Testing of General Ecological Theory, J.R. Barnes and G.W. Minshall (Eds.), Plenum Press, NewYork.

Holmes, R. (1982). Water resources, in Atlas of Victoria, J.S. Duncan (Ed.), Victorian GovernmentPrinting Office, Victoria.

Hunter, K. (1993). Victorian Water Quality Monitoring Network: August 1990 - December 1992.State Water Laboratory of Victoria, Melbourne.

Hunter, K. and Zampatti, B. (1994a). Victorian Water Quality Monitoring Network - Summary ofHistorical Data 1975-1992 Report No 115, State Water Laboratory of Victoria

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Hunter, K. and Zampatti, B. (1994b). Victorian Water Quality Monitoring Network - Annual Report1993. Report No 112, State Water Laboratory of Victoria.

Jenkin, J. (1982). Physiography, in Atlas of Victoria, J.S. Duncan (Ed.), Victorian GovernmentPrinting Office, Victoria.

Johnstone, P. (1994). Algal Bloom Research in Australia. Water Resources Management Committee,Occasional Paper WRMS No 6. Agriculture and Resource Management Council of Australia andNew Zealand.

Land Conservation Council (1989). Rivers and Streams Special Investigation Report. LandConservation Council, Victoria.

Marchant, R., Metzeling, L., Graesser, A., and Suter, P. (1985). The organisation ofmacroinvertebrate communities in the major tributaries of the LaTrobe River, Victoria, Australia.Freshwater Biology 15:315-331.

Metzeling, L. and McKenzie-Smith, F. (in prep). Effects of Fish Farms on Two Upland Rivers.

Metzeling, L., Newall, P. and Croome, R. (1993b). Biological Monitoring of the Invertebrates,Phytoplankton and Diatoms of the Wimmera River. Scientific Report Series No. 90/019,Environment Protection Authority, Victoria.

Metzeling, L., Tiller, D. and Hunter, M. (1993a). Inland Water Quality Monitoring Network 1991Yearly Report. EPA Publication No. 360. Environment Protection Authority, Victoria.

Mitchell, P. and Clark, H. (1991). An Environmental Study of Merri Creek. Report No. WQ-44, toEPA by Rural Water Commission.

Morley, R., Newall, P. and Bennison, G. (1989). The Biology and Chemistry of Selected MountStirling Sub-Alpine Streams (Survey and Monitoring 1986-1988). Report No. 100, Water, Materialsand Environmental Science Branch, Rural Water Commission, Victoria.

Omernik, J. (1987). Ecoregions of the conterminous United States. Annals of the Association ofAmerican Geographers 77:118-125.

Paine, D. (1982). Vegetation, in Atlas of Victoria, J.S. Duncan (Ed.), Victorian Government PrintingOffice, Victoria.

Pettigrove, V. (1989). Biological Monitoring of the Yarra River Using Macroinvertebrates.Environment Protection Authority Publication No. SRS 88/014, Environment Protection Authority,Victoria.

Reed, J. (1992). A Biological Assessment of Lower Kororoit Creek. Environment ProtectionAuthority Publication No. SRS 90/012, Environment Protection Authority, Victoria.

Reed, J. and Newall, P. (1990). An Environmental Study of the Plenty River. EnvironmentProtection Authority Publication No. SRS 88/015, Environment Protection Authority, Victoria.

Robinson, D. (1988). Biological Surveillance of the LaTrobe River 1982-1986. EnvironmentProtection Authority Publication No. SRS 87/054, Environment Protection Authority Victoria.

Rural Water Commission (1990). Victorian Surface Water Information to 1987, Volumes I-IV. RuralWater Commission of Victoria, Melbourne.

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Tiller, D. (1988). Impact of Sewage Effluent on the Benthic Macroinvertebrate Community of theUpper Thredbo River. Unpublished Masters Thesis, Faculty of Applied Science, University ofCanberra, ACT.

Tiller, D. and Bate, N. (in prep). An Ecological Assessment of the Lower Goulburn River.

Webb, C. (1982). Rural production, in Atlas of Victoria, J.S. Duncan (Ed.), Victorian GovernmentPrinting Office, Victoria.

Wetzel, R.G. (1983). Limnology. Saunders College Publishing Co., Philadelphia.

Wilson, R. (1994). Generalised land use (1990) - Wimmera Catchment Water Quality Investigation.Unpublished map, Department of Conservation and Natural Resources.

EPA Publication 478© EPA Victoria, 1995

preliminary nutrient guidelines for victorian inland streams · strategy. a major part of the...

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