PRELIMINARY NUTRIENT GUIDELINES FOR VICTORIAN INLAND STREAMS

Publication 478 June 1995

PRELIMINARY NUTRIENT GUIDELINES FOR VICTORIAN INLAND STREAMS

David Tiller and Peter Newall

Catchment and Marine Studies

Environment Protection Authority Government of

June 1995 PRELIMINARY NUTRIENT GUIDELINES FOR VICTORIAN INLAND STREAMS

Catchment and Marine Studies

Environment Protection Authority Olderfleet Buildings 477 Collins Street Victoria 3000

June 1995

ISBN 0 7306 2839 6 FOREWORD

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

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

An important step in the development of CNMPs is the establishment of nutrient targets. This report outlines preliminary guidelines for phosphorus and nitrogen concentrations in Victorian inland streams to assist in the development of CNMPs and to aid in the protection of the aquatic environment.

Preliminary guidelines have been determined for seven river regions across the State with similar environmental attributes and stream systems. Within each river region, pertinent available biological and 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 responses to nutrients for several regions in Victoria were highlighted. There is clearly a need for additional research to further our knowledge.

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

BRIAN ROBINSON CHAIRMAN

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ACKNOWLEDGEMENTS

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

v CONTENTS

FOREWORD...... iii

ACKNOWLEDGEMENTS...... v

1. INTRODUCTION ...... 1 1.1 Background...... 1 1.2 Scope ...... 1 1.3 Aims...... 2

2. APPROACH...... 3 2.1 Introduction...... 3 2.2 Information Sources ...... 3 2.3 The River Regions...... 3 2.3.1 Highlands River Region ...... 4 2.3.2 Murray Foothills River Region...... 4 2.3.3 Murray Plains River Region ...... 4 2.3.4 Southern and Isolated Foothills River Region...... 4 2.3.5 Northwest Plains River Region...... 5 2.3.6 Southwest River Region...... 5 2.3.7 Southern Lowlands and Urban River Region...... 5

3. HOW TO USE THE GUIDELINES...... 9 3.1 Guideline Concentrations ...... 9 3.2 Current Nutrient Concentrations Versus the Guidelines ...... 9 3.3 Flows ...... 9 3.4 Geographical Precision of the Regions and Guidelines ...... 10

4. THE NUTRIENT GUIDELINES...... 11 4.1 Highlands River Region ...... 11 4.2 Murray Foothills River Region ...... 12 4.3 Murray Plains River Region ...... 13 4.4 Southern and Isolated Foothills River Region ...... 14 4.5 Northwest Plains River Region...... 15 4.6 Southwest River Region ...... 16 4.7 Southern Lowland and Urban River Region...... 17

5. CONCLUSIONS...... 20

6. REFERENCES CITED...... 23 Nutrient Guidelines

1. INTRODUCTION

1.1 Background

Nutrient concentrations in most surface water bodies across Victoria have increased through human activities that have created a variety of diffuse and point source inputs (Department of Water Resources 1989). Elevated nutrient concentrations are often cited as contributing to nuisance plant growths 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 each water body and its consequent need for individually assigned criteria, or else provide a very broad range of values which will cover most water types and situations.

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

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

The immediate impetus for the preparation of this document has come from the Nutrient Management Strategy for Victorian Inland Waters (Government of Victoria, 1995). A core component of the Strategy 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 of CNMPs will be greatly assisted by the provision of achievable yet ecologically meaningful nutrient guidelines. Provision of guideline concentrations for use in the preparation of CNMPs is an Environment Protection Authority responsibility (Government of Victoria 1995).

1.2 Scope

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

High nutrient concentrations are only one of the problems facing catchment managers. Attainment of nutrient 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 information of lakes and impoundments in Victoria. In addition, impoundments are typically managed for water supply or hydro electricity, with ecological integrity being compromised. Although lakes and impoundments are not the subject of this document, there is a need to consider the setting of nutrient guidelines 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 sewage effluent (Metzeling et al. 1993a). Many lakes are terminal systems, and adding nutrients can have

1 Nutrient Guidelines very long term consequences. To prevent problems due to nutrient enrichment it is evident that input of nutrient rich effluents should not be occurring, and that considerable effort should be put into controlling nutrients originating from non-point source discharges, including irrigation return waste waters.

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

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

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

Nitrogen to phosphorus ratios are not used in the guidelines. There is a lack of consensus on the use of nitrogen to phosphorus ratios, in particular the critical ratios, and the forms of nitrogen and phosphorus to use. A particularly useful critique of nitrogen to phosphorus ratios can be found in the Australian 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 are sufficiently similar to allow the allocation of nutrient guidelines (as described below);

· to provide preliminary, quantitative nutrient guidelines for inland rivers and streams for each region;

· 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 biological factors. The first aim required the delineation of regions despite the wide range of aquatic environments and conditions to be characterised.

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

2.2 Information Sources

These preliminary guidelines are primarily based on studies from south eastern Australia in which water quality was measured concurrently with biological sampling. Although this report was initiated due to concerns about excessive plant growths, the allocation of nutrient guidelines for maintenance of aquatic ecosystem integrity must also include consideration of fauna - particularly since many of the ecological studies involving responses to nutrient additions are zoological in nature. Increased nutrients have been demonstrated to increase populations of invertebrate fauna through higher plant production 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 nutrient concentrations (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 a result of nutrient additions. The use of biota in assessment is a key feature of the guidelines, allowing the formulation of ecologically derived values.

In regions where there are insufficient studies incorporating biota and nutrients, data from long term water quality monitoring has been combined with available biological information to allow a tentative assessment of nutrient effects within the region. The resultant guidelines were prepared following examination 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 by Omernik (1987) for the United States were based on climate, soils, physiography, and potential natural vegetation, with the often overlapping nature of these features assisting the allocation of boundaries. 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 by Omernik (1987) for delineating ecoregions, river regions in this report are partially defined using subjective assessment and local knowledge of the areas. Seven river regions are identified (Figure 1).

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2.3.1 Highlands River Region Altitude is the primary feature delineating this region. Most of the areas in Victoria above 1000m are within the Highlands River Region, which is generally minimally disturbed and predominantly forested. The region also includes all the alpine areas in Victoria. Median annual runoff in the region varies from below 125 mm to above 1000 mm (Holmes 1982). Major forest types range from tall open forest to open forest (Carnahan 1990). Streams in this region are typically very shallow with clear 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 the region. The alpine streams tend to have open vegetation around the banks, whereas at lower altitudes the banks tend to be densely forested.

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

2.3.2 Murray Foothills River Region This region is delineated as part of the eastern Victorian uplands with moderate relief and drainage to the north of the . Most of the region has an annual median runoff between 50 and 125 mm, with the lower values being in the north and western areas (Holmes 1982). The Upper Murray, the Kiewa, Ovens and Goulburn Rivers all flow through the Foothills, after originating in the Highlands. The Broken, Campaspe and catchments all originate in the Murray River Foothills. Towns within the region include Corryong, Bright, Yea, , and Daylesford. Mt Beauty, in the Catchment, lies near the boundary between this river region and the Highlands River Region.

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

2.3.3 Murray Plains River Region Occupying the north east to north-central part of the state, the catchments in this region also drain to the Murray River, and receive waters from the Murray Foothills and - to a lesser extent - the Highlands River Regions. The region includes a small portion of the Kiewa Catchment, the lower portions of the Ovens and Goulburn catchments, and most of the Broken, Campaspe and Loddon catchments. Towns which typify the region include , Shepparton, and Wangaratta. and 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 low median annual runoff of less than 25 mm (Holmes 1982).

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

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

4 Nutrient Guidelines

Otway Ranges, the Strzelecki Ranges, and . Towns within the Southern Foothills include , Buchan, Licola, Aberfeldy and Ballarat. Towns within the Isolated Foothills include Mirboo North, , 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 125 mm, exceeding 125 mm at Wilsons Promontory, 250 mm in parts of the Grampians, 500 mm in the Strzelecki Ranges, and 750 mm in the Otway Ranges. Most of the region's natural vegetation cover was medium open forest, with patches of tall open forest in the Strzelecki Ranges and the Otway Ranges, and low open forest in the Grampians (Carnahan 1990). The current vegetation cover of the region includes some largely undisturbed forests in the eastern southern foothills, as well as areas subjected to forestry operations, including clear felling. Further west there are large areas of pasture and croplands (Webb 1982).

Rivers within the region have some similar characteristics to those of the Murray Foothills, being typically 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 boulders forming the stream bed.

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

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

2.3.6 Southwest River Region Most 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 annual runoff in the eastern half of the region is typically between 10 and 50 mm, and between 50 and 125 mm in the western half (Holmes 1982). The natural vegetation of the region was predominantly woodland 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 open woodland (Paine 1982). Towns within the region include Hamilton, Colac, Casterton and Camperdown.

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

2.3.7 Southern Lowlands and Urban River Region In contrast to the other river regions, this region is largely delineated by human influences. The catchments in this region contain the substantial portion of Victoria's population and industry, and includes greater Melbourne, Geelong and the . The remainder is mostly under intensive agriculture.

5 Nutrient Guidelines

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 the remainder forming a Yarra and Gippsland Plain River Region, this region is defined on purely human influences. Delineation on the basis of human influences also results in difficulties in typifying the region and its rivers in terms of other natural features. Median annual runoff ranges from less than 25 mm 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 the middle and lower Yarra, Maribyrnong, Werribee, and Moorabool catchments, all but the uppermost portions 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 and moderately deep. Tributaries to these are often deeply incised, channelised, contain litter, and have high 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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8 Nutrient Guidelines

3. HOW TO USE THE GUIDELINES

3.1 Guideline Concentrations

Background concentrations in this reportare those which would be expected for undisturbed streams in a given river region. Threshold concentrations are the estimated maxima above which damage to the ecological community will occur. The threshold concentrations are therefore the guideline maxima concentrations recommended for the restoration or maintenance of the aquatic ecosystems within a river region. The nutrient concentrations described as "major impact" concentrations in this report 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 restoration of degraded streams, or the maintenance of healthy streams. Streams or stream reaches which have higher than recommended nutrient concentrations should be managed with the aim of reducing nutrient concentrations to within the recommended values.

The guidelines are not ecological optima, rather they are threshold levels beyond which marked ecosystem degradation has been observed. Therefore, in streams where nutrient concentrations are below 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. During base flow conditions, any excess of nutrients has potential to contribute to excessive plant growths and a resultant ecosystem disturbance. The guidelines are not median or percentile values, and should not be exceeded at any time during base flow conditions.

Notwithstanding the above, it is recognised that dissolved and suspended sediment loads increase greatly during high flow periods, and that the nutrients contributed during these events will add to ecosystem stress. Indeed, the bulk of a stream's total nutrient load is transported during these infrequent, high flow events. However, from a monitoring perspective, high flow events are comparatively rare, and nutrient concentrations during these events are strongly influenced by the magnitude 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 is therefore more useful to set guidelines for baseflow conditions, which are more stable and generally prevail.

Many streams in the State are commonly dry. Intermittent streams flow only seasonally, while streams that are generally dry and have unpredictable flows are called episodic. Intermittent and episodic streams are very common in Victoria, particularly in the north. Little is known about these streams, although the limited data available indicate that they contain a rich aquatic fauna when surface water is present (Boulton and Suter 1986, Brooks and Boulton 1991). The fate, behaviour and effects of pollutants in these streams is virtually unknown. Perennial streams on the other hand are reasonably well understood, and our understanding of intermittent and episodic streams is, unfortunately, based on concepts mostly derived from perennial streams. However, the impact of pollutants discharged to non-flowing streams is likely to be substantially greater than that experienced by perennial streams (Boulton and Suter 1986) and consequently, effluent discharges should not occur to 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 going to result in exceptions. Similarly, the boundary between two adjacent river regions will necessarily be broad. In situations where there are clear exceptions, or where a stream reach is close to a regional boundary, there will clearly be a need for specific assessment by the catchment manager. These guidelines therefore provide regional values, against which individual stream nutrient objectives can be 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 1,200 m) in Kosciusko National Park, NSW, found a substantial impact resulting from a sewage effluent discharge (Tiller 1988), which thereafter diminished with distance downstream. The results from that study 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 are consistent with those of Cullen (1983), who found no biostimulation of attached filamentous algae in the Crackenback (Thredbo) River with a phosphorus concentration of 0.020 to 0.025 mg L-1 and nitrogen concentrations typically below 0.150 mg L-1, and obvious biostimulation with a phosphorus concentration of 0.050 mg L-1 and a nitrogen concentration of 0.360 mg L-1. The background and threshold nutrient concentrations, and the concentrations at which substantial impacts were observed are displayed in Table 4.1.

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

Total Phosphorus Total Nitrogen Background 0.010 0.070 Threshold 0.020 0.150 Major Impact 0.050 0.250

Background total phosphorus concentrations reported by Tiller (1988) are similar to those reported by Morley et al. (1989), who found healthy aquatic communities in Mt Stirling streams with median total phosphorus concentrations ranging from 0.010 to 0.014 mg L-1 across six sites. Although only nitrate/nitrite was recorded for the Mt. Stirling study, median concentrations ranged from 0.008 to 0.048 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 farm effluent of differing nutrient concentrations entering three streams in the Goulburn catchment - the Murrindindi and Rubicon Rivers, and Snobs Creek. These data showed healthy invertebrate communities at sites upstream of the effluent discharges, where total phosphorus concentrations were generally in the range of 0.010 to 0.020 mg L-1, and total nitrogen concentrations were up to 0.200 mg L-1. The study also monitored sites at increasing distances downstream from the effluent discharges, with consequent dilution of the nutrients. At concentrations of 0.090 mg L-1 total phosphorus and 0.600 mg L-1 total nitrogen, the invertebrate community was clearly disturbed. Between 0.050 and 0.090 mg L-1 total phosphorus, and 0.400 to 0.500 mg L-1 total nitrogen, the biota appeared healthier, yet still disturbed, and had not recovered until total phosphorus concentrations were approximately 0.030 mg L-1 and total nitrogen was less than 0.200 mg L-1. The background and threshold nutrient concentrations, and the concentrations at which substantial impacts were observed are displayed in Table 4.2.

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

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

Support for the background concentrations is provided by long term physico-chemical data for the at Bright. From 35 samples collected between 1975 and 1987, median total phosphorus concentrations were 0.017 mg L-1 and median total nitrogen concentrations were 0.300 mg L-1 (Rural Water Commission 1990). From 12 samples collected in 1993, the median total phosphorus concentration 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 a healthy stream (EPA unpublished data).

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

Total Phosphorus: 0.030 mg L-1 Total Nitrogen: 0.200 mg L-1

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4.3 Murray Plains River Region

In the lower nutrient concentrations steadily increase from downstream of the diversion weir at Nagambie to the 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 invertebrate communities, however, vary surprisingly little compared to the changes that occur in foothills areas with similar nutrient increases. The invertebrate communities in lowland reaches of the Ovens and Campaspe Rivers also had a similar fauna to the lower Goulburn River (EPA unpublished data), even though nutrient concentration varied substantially (Table 4.3). The lowland reaches of the River Murray tributaries generally have high suspended solids, substantially reducing light penetration, thus lessening the potential for most planktonic and submerged plant growth. The influence of nutrients on plant and invertebrate communities is, therefore, likely to be limited.

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

In addition to nutrients, current velocity and turbidity are major factors in the formation of blooms. It is likely that in the lower Loddon River, the lower reaches of the lower Goulburn River and possibly the , nutrients are always in excess, and blooms are limited by light penetration and flows. During prolonged low flow periods where water clarity increases and turbulence does not negate cell buoyancy, streams with nutrient concentrations above the recommended guidelines are at risk of developing nuisance blooms. Sediments may also be a major potential source of nutrients in slow flowing lowland rivers. Their importance is unknown.

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

River Site Total phosphorus Total nitrogen Suspended solids Ovens Peechelba 0.044 0.440 24 Goulburn McCoys 0.120 1.010 50 Goulburn Undera Nth 0.090* 0.700* - Goulburn Murchison/Arcadia 0.025* 0.300* 16** Campaspe Rochester 0.073 1.210 27 Loddon Appin 0.100 1.300 70 All data from long term median, EPA Water quality Network unpublished data, except; * from Tiller 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 Nitrogen Background 0.025-0.045 0.300-0.500 Threshold 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 this region. This limitation is underscored by the occurrence of severe blooms in streams within the region. The Murray Plains River Region is therefore a high priority region for concurrent nutrient and biological studies. The occurrence of occasional planktonic blooms suggests that monitoring of the phytoplankton is also needed. Design of monitoring programs should include both long term, low intensity sampling and more intensive sampling during times of high bloom risk.

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

Total Phosphorus: 0.050 mg L-1 Total Nitrogen: 0.600 mg L-1

4.4 Southern and Isolated Foothills River Region

Water quality data which are available indicate that the forested catchment ecosystems of this river region are of similar (high) quality to the forested catchment streams in the Murray Foothills River Region (Marchant et al. 1985; Hunter and Zampatti 1994b and EPA unpublished data). Although these 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, it is reasonable to use the Murray Foothills River Region guidelines for the Southern and Isolated Foothills 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 five sites from southern foothills and two sites from isolated foothills (Upper Gellibrand in the Otway Ranges, and Big Cord in the Grampians).

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

River Site Total Phosphorus Total Nitrogen Bemm Princes Hwy 0.011 0.365 Buchan Buchan 0.011 0.226 Timbarra d/s Wilkinson Ck. 0.016 0.231 Mitchell Glenaladale 0.011 0.104 Aberfeldy Beardmore 0.007 0.107 Macalister Licola 0.007 0.100 Gellibrand Upper Gellibrand, Otways 0.021 0.330 Glenelg 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 Isolated Foothills River Region. This region should therefore be given high priority to allow confirmation or reassessment of these guidelines.

Based on the above information, including the apparent similarity of this river region to the Murray Foothills, the preliminary nutrient guideline maxima recommended for the Southern and Isolated Foothills River Region are:

Total Phosphorus: 0.030 mg L-1 Total Nitrogen: 0.200 mg L-1

4.5 Northwest Plains River Region

Combined biological and chemical data for the region are restricted to the middle and lower system, which - on the basis of these data - was described as an intermittently flowing, 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 the course 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 of the region.

Total phosphorus concentrations for many rivers within the region are comparable to background levels for the Murray Plains River Region (Table 4.6). In contrast, the total nitrogen levels are typically 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 several rivers in the Northwest Plains River Region.

River Site Total Phosphorus Total Nitrogen Wimmera Glenorchy 0.030 0.742 Wimmera Horsham 0.052 0.931 Wimmera Dimboola 0.041 0.909 Avon Donald 0.045 0.904 Avoca Coonooer 0.057 0.908 Source: Hunter and Zampatti (1994b)

Consideration of acceptable nutrient concentrations for the region is complicated by the extremely variable flow and the temporary effects of episodic flows upon nutrient concentrations. During the period of sampling by Metzeling et al. (1993b), the only occasions when cyanobacteria exceeded approximately 1000 cells or more per millilitre, were during low flows immediately following large flow events. Corresponding to the large flow events were temporary massive increases in nutrient concentrations. At the site downstream of Dimboola (Table 4.6), 1993 median total phosphorus concentrations were 0.041 mg L-1, and median total nitrogen was 0.909 mg L-1. At the same site a cyanobacterial bloom occurred in 1987 following a high flow event and total phosphorus and nitrogen 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 nutrient concentrations 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 quality has been adopted. Therefore, interim guideline maxima for the Northwest Plains River Region are:

Total Phosphorus: 0.050 mg L-1 Total Nitrogen: 0.900 mg L-1

4.6 Southwest River Region

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

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

River Site Total phosphorus Total nitrogen Glenelg R. Casterton 0.018 0.640 Wannon R. Henty 0.035 0.950 Hopkins R. Framlingham 0.031 1.370 Mt 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, and least impacted sites need to be identified and incorporated into community and nutrient sampling programs. Concurrent biological and nutrient assessment of point source nutrient inputs may assist these studies.

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

Total Phosphorus: 0.035 mg L-1 Total Nitrogen: 1.000 mg L-1

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 industrial activity occurs within this region. The predominance of human influences, particularly in the urban areas, make the assigning of realistic, but attainable, guidelines difficult. In addition, little information 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 available clearly indicate the generally poor state of water quality and ecosystem health in these rivers and streams (Table 4.9) (Metzeling et al. 1993a; Reed and Newall 1990; Reed 1992; Mitchell and Clark 1991; Pettigrove 1989; Robinson 1988).

For the purpose of setting nutrient objectives, the rivers and streams of the region have been divided into 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 Barwon Rivers and ); 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 quality compared 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 and removal of riparian vegetation, the rural lowland rivers and streams have similar flow and water quality characteristics to Murray Plains rivers (Tables 4.3 and 4.9), suggesting that it is reasonable to use the Murray Plains guidelines for this part of this region. The LaTrobe State Environment Protection Policy (SEPP) has recommended total phosphorus and nitrogen concentrations for the (Environment Protection Authority 1995). These are based on percentiles and cannot be directly related to the preliminary guidelines.

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

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

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

River Site Total phosphorus Total nitrogen LaTrobe R. Willow Grove 0.038 0.670 LaTrobe R. Rosedale 0.091 0.930 Yarra R. Launching Place 0.270 0.640 Werribee R. u/s Werribee 0.089 1.040 Barwon R. Rickets Marsh 0.049 0.630 All data from long term median, EPA unpublished data

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

River Site Total phosphorus Total nitrogen Yarra R. Warrandyte 0.100 1.090 Yarra R. Fairfield 0.125 1.240 Barwon R. Geelong 0.128 1.240 All data from long term median, EPA unpublished data

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

River Site Total phosphorus Total nitrogen Plenty R. Greensborough* 0.300 2.460 Merri Ck. Fitzroy* 0.210 1.420 Maribyrnong R Sunshine 0.230 0.850 Kororoit Ck. Altona 0.695 4.010 Dandenong 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 be directed towards developing nutrient reduction strategies and assessing their effectiveness, rather than reassessment of the guidelines.

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

Rural rivers and streams: Total Phosphorus: 0.050 mg L-1 Total Nitrogen: 0.600 mg L-1

Urban rivers - interim: Total Phosphorus: 0.080 mg L-1 Total Nitrogen: 0.900 mg L-1

Urban rivers - long term: Total Phosphorus: 0.050 mg L-1 Total Nitrogen: 0.600 mg L-1

Urban tributaries - interim: Total Phosphorus: 0.100 mg L-1 Total Nitrogen: 1.000 mg L-1

Urban tributaries- long term: Total Phosphorus: 0.030 mg L-1 Total Nitrogen: 0.200 mg L-1

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5. CONCLUSIONS

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

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

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

Concentrations of nutrients in many streams across the State exceed the guidelines. Priority should be given to nutrient reduction strategies in many of Victoria's rivers and streams, in particular the large lowland rivers and urban streams, which are typically well in excess of their preliminary guideline concentrations.

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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. Australian and New Zealand Environment and Conservation Council.

Biggs, B. and Lowe, R. (1994). Responses of two trophic levels to patch enrichment along a New Zealand 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 Environmental Studies Series, Publication Number 394, Ministry for Conservation, Victoria.

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

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

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

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

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

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

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

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

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

Holmes, R. (1982). Water resources, in Atlas of Victoria, J.S. Duncan (Ed.), Victorian Government Printing 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 of Historical 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 Report 1993. Report No 112, State Water Laboratory of Victoria.

Jenkin, J. (1982). Physiography, in Atlas of Victoria, J.S. Duncan (Ed.), Victorian Government Printing 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 and New Zealand.

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

Marchant, R., Metzeling, L., Graesser, A., and Suter, P. (1985). The organisation of macroinvertebrate 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 1991 Yearly 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, to EPA by Rural Water Commission.

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

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

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

Pettigrove, V. (1989). Biological Monitoring of the 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 Protection Authority Publication No. SRS 90/012, Environment Protection Authority, Victoria.

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

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

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

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Tiller, D. (1988). Impact of Sewage Effluent on the Benthic Macroinvertebrate Community of the Upper Thredbo River. Unpublished Masters Thesis, Faculty of Applied Science, University of Canberra, 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 Government Printing 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

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