ENVIRONMENT REPORT

A SNAPSHOT OF THE ENVIRONMENTAL CONDITION OF VICTORIAN

Publication 1303 February 2010

SUMMARY value should trigger an investigation to determine the cause. This investigation could range from an This report provides an assessment of the extensive scientific study to a simple desktop environmental condition of a range of Victorian lakes consideration of the situation. The triggering of an in 2007. It sets a baseline against which climate indicator value may indicate a serious threat to the change and other future impacts on condition can environmental condition of a lake or may be a be compared. Lake condition was based on biological reflection of naturally occurring seasonal trends for and water quality objectives contained in the the lake ecosystem. Environmental quality guidelines for Victorian lakes Using the Guidelines to assess the current condition of (EPA publication 1302). ’s lakes provides baseline data for measuring Overall, lakes in agricultural and urban settings were the potential future impacts. Possible impacts include more stressed than lakes surrounded by forest, those due to climate change, although the dry climate national park or coastline. Many of the poorer quality over the past decade has meant that some of those lakes were located in the Western District, where the impacts are already being seen. shallow lakes were particularly affected by the The potential effects of climate change on Victorian combined effects of drought and wide-ranging threats lake ecosystems are discussed in more detail in How from human activities. will climate change affect Victorian lakes? (EPA 2008). Recent studies such as Findings of western Victorian INTRODUCTION lakes eel death investigation 2004—06 (EPA 2007) also highlight the stress experienced by lake This publication provides a snapshot assessment of ecosystems during prolonged drought and provide an the environmental condition of a range of Victorian insight into the impacts that may be associated with a lakes. The assessment is based on the indicators and changing climate. guideline values detailed in the Environmental quality guidelines for Victorian lakes, hereafter referred to as ‘the Guidelines’ (EPA 2010). Thirty-one natural lakes were assessed using measurements of water, biological and habitat quality. Lakes were defined as natural water bodies dominated by open water. In interpreting the information in this report it is important to consider that the results represent a single sampling event between January and April 2007. Conditions can change rapidly in aquatic ecosystems and more frequent sampling would be required to gain a more thorough understanding of lake ecosystem function and condition. Nonetheless, this report provides an overview of the condition of Victorian lakes. In addition to providing a baseline assessment of the Figure 1: Lake Elizabeth, Great Otway National Park condition of Victorian lakes, this study trialled the use — a lake in excellent condition. of the Guidelines, allowing an evaluation of the performance of the indicators and guideline values. The Guidelines follow the principle of risk-based assessment of ecosystems. Within a risk assessment framework, the failure to meet a guideline indicator

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ASSESSMENT METHODS at depths of five and 10 metres (or, for lakes less than 10 metres deep, at surface, middle and bottom depth). Like many aquatic ecosystems, lakes are complex and The presence and abundance of blue-green algae variable. A variety of indicators (measures that (cyanobacteria) is also important as an indicator of indicate the overall condition of the ecosystem or a potentially toxic blue-green algal blooms. A component of the ecosystem) are needed to phytoplankton sample was taken to determine the understand their condition. The indicators chosen for composition of the algal community. this snapshot assessment are those recommended in the Guidelines for ambient monitoring of the Assessment of habitat quality and catchment environmental condition of lakes. The assessment of threats environmental condition is based on the values The availability of good-quality habitat for aquatic life specified in the Guidelines. is critical for lake ecosystem functions and maintaining Water quality indicators biodiversity. Additionally, identification of catchment threats is important for targeting management Table 1 lists the physical and chemical water quality strategies to improve lake condition. The assessment indicators tested. Depth profiles of in situ water quality method used in this study was the Lakes habitat parameters (dissolved oxygen, temperature, pH and survey (LHS) (Rowan et al. 2006) recommended in the electrical conductivity) were collected from the centre Guidelines (EPA 2009). of the lake. As part of performing the Lake habitat survey, indices of lake habitat quality assessment (LHQA) and lake Table 1: Water quality indicators habitat modification scores (LHMS) were generated. Lake habitat quality assessment refers to the quality Type of measure Parameters measured of the in-lake and surrounding-lake habitat while lake habitat modification score refers to the human Dissolved oxygen (DO) modification of these natural lake habitats. Electrical conductivity (EC) Habitat assessments (Figure 2) consisted of four Physicochemical pH habitat plots — one in each quarter of the lake. The physical environment was assessed within the riparian, Turbidity shore and littoral zones of the lake. Measures included Temperature riparian vegetation structure and nativeness, shore and littoral substrates, modifications, macrophytes Total phosphorus (TP) Nutrients and in-lake habitat features for fish and Total nitrogen (TN) macroinvertebrates (including submerged logs and organic matter). Phytoplankton (algae) Chlorophyll Human pressures were also assessed across the entire lake. These included bank construction, catchment and Extreme values in these parameters may lead to the adjacent land use, and recreational activities such as death of some aquatic organisms and affect the fishing and boating. composition of aquatic communities. Further details of the recommended protocols for Analysis of inorganic nutrients indicates the biological habitat assessment are contained in the Guidelines productivity of a lake. Phosphorus and nitrogen are (EPA 2009). generally the most important inorganic nutrients influencing lake productivity. Phosphorus is the major limiting nutrient in most inland lakes, although in some cases, for example in , nitrogen is the limiting nutrient (Herpich 2002). The productivity of a lake is a key factor determining its state. Phytoplankton (microscopic photosynthetic organisms sometimes referred to as algae) are an important indicator of the status of lakes. More productive ‘eutrophic’ lakes have higher phytoplankton biomasses than low-productivity ‘oligotrophic’ lakes. Chlorophyll-a is the dominant pigment in phytoplankton and is commonly used as a surrogate measure of phytoplankton biomass. Chlorophyll-a was sampled from the centre of the lake at the surface and

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in Figure 3. Appendix 1 details individual assessments of lakes against each guideline value. 1. Riverine lakes Hattah lakes The Hattah lakes, located in the Hattah-Kulkyne National Park in north-west Victoria, are riverine floodplain lakes that are filled from the Murray River system during flood events (see inset in Figure 3). In 2005, 2006 and 2007, the lakes received environmental water allocations pumped from the Murray River due to concern that fringing river red gum communities were declining in health from the prolonged drought (EPA and MDFRC 2008). During the snapshot period, most lakes had extensive Figure 2: Habitat assessment at . blue-green algal blooms (Figure 4). These resulted in many lakes not meeting a number of water quality guidelines, as the algal blooms affected other water Biological indicators quality measures such as DO and pH. For example, Macroinvertebrates were collected at two sites within samples from Lake Hattah and Lake Lockie met the the littoral zone of each lake. Sweep samples were guideline values for only one of the seven water collected using the Rapid bioassessment methodology quality indicators. for rivers and streams (RBA) (EPA Victoria 2003a). All of the lakes triggered guideline values for both The biological condition of each lake was assessed total phosphorus and total nitrogen. The high nutrient using two indices: the total number of invertebrate levels, combined with long day lengths and warm families collected and VLAKES. VLAKES is a biological temperatures, contributed to the algal blooms. index developed specifically for Victorian lakes based Chlorophyll-a guideline values were triggered for lakes on aquatic macroinvertebrate sensitivities to Lockie, Hattah, Arawak and Brockie. Substantial disturbance and is explained in more detail in the release of phosphorus from the lake sediment is Guidelines (EPA 2009). typical of these eutrophic floodplain lakes following re- wetting after a dry period. Given that these lakes are The number of families is a simple measure of located within a National Park with minimal human diversity. Generally, high diversity indicates a healthy pressures, the high nutrient levels may not necessarily ecosystem. As macroinvertebrate diversity is be of concern. They may instead simply represent influenced by the natural salinity of a lake, the natural processes for these types of lakes. guideline values are adjusted according to the lake’s electrical conductivity (Appendix 1). Despite the algal blooms, biological results for the Hattah lakes indicated that macroinvertebrate diversity was not reduced. In fact, samples from Lake ENVIRONMENTAL CONDITION Arawak, Lake Hattah, Lake Lockie and Lake Yerang recorded 13—23 families, indicating these ecosystems An assessment of the environmental condition of the were quite diverse. However, VLAKES scores were lakes investigated is presented below (grouped by lake relatively low, indicating that although the community type). A statewide overview of lake condition is shown was quite diverse, some sensitive families were not present — probably due to poor water quality.

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Figure 3: Summary of the ecological condition of Victorian lakes.

The snapshot of condition of the Hattah lakes reinforces the need to understand the lake ecosystem and choose an appropriate sampling regime. These types of lakes undergo dramatic successional changes in ecology and water quality from filling to drying. A single snapshot in summer would be inadequate to fully assess the lakes’ condition which, at least in terms of water quality, would be markedly different in winter. Data across seasonal cycles would allow the underlying causes and effects of changing water quality to be better understood, so that informed management decisions about the lakes could be made. Overall the Hattah lakes appear to be in moderate environmental condition, although inferences are limited by the snapshot approach. Algal blooms may Figure 4: Lake Hattah in February 2007 showing an be a natural feature in these lakes, but have likely extensive blue-green algal bloom. been exacerbated by the extended dry period before the artificial re-wetting.

Kerang lakes All Hattah lakes had a moderate score for the habitat quality assessment (LHQA). However, lake habitat The Kerang region in north-central Victoria (see inset modification scores (LHMS) were low, reflecting the in Figure 3) is significant for its high number and relatively low level of modification to the catchment, diversity of (Lugg et al. 1989), many of which riparian, shore and littoral habitats. This is expected have been listed as wetlands of international for lakes located within national parks where significance under the Ramsar Convention on environmental value is high and human impacts are Wetlands. Lakes in this region also act as important relatively low. storage basins in the Torrumbarry irrigation system. has been classified as a sanctuary in

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accordance with the Directory of Important Wetlands that recreation is a main focus of the lake (DNRE (ANCA 1996). Reedy Lake met five of the seven water 1996). quality guideline values but pH and turbidity were Previous studies on have identified the triggered. The lake habitat quality assessment overall environmental status to be poor as a result of indicated moderate habitat quality and the lake habitat poor water quality, altered hydrology, low habitat modification score identified a number of pressures diversity and low native species diversity (DNRE 1996). that may be adversely affecting the environmental These results suggest that the environmental condition of the Reedy Lake ecosystem. condition of Lake Boga had not improved, as only one Cockatoo (Figure 5) was among the most guideline value was met from all water quality, diverse of the floodplain lakes for both aquatic plants biological quality and habitat quality parameters. and macroinvertebrates. However, overall the lake’s A major fish death event, including carp, Murray Cod habitat modification score was poor and indicated and Yellow Belly, occurred at Lake Boga during significant human pressures. Despite this, water January 2008. EPA investigations showed this was quality guideline values were triggered for only one associated with significantly reduced water and indicator — pH. oxygen levels and high salinity. This was several Investigation of the likely cause of the low pH may months after the snapshot sampling but may indicate require an understanding of the diurnal cycle of this that the lake had been under stress for some time. lake. The water quality, biological and habitat quality While the lake habitat quality and modification scores results indicate that there is potential for the current indicated a high level of human-induced stress, human stressors to reduce the environmental drought is the most likely cause of the poor condition of the Cockatoo Lagoon ecosystem. environmental condition of Lake Boga. The lake is currently dry and no longer used as part of the

irrigation system. Water quality guideline values were triggered for total phosphorus and turbidity and all biological quality indicators for Kangaroo Lake. Fish predation may be contributing to low macroinvertebrate diversity, a consequence of stocking with fish for recreational angling. Lake habitat quality was assessed as moderate and the lake habitat modification score indicated a high level of human-induced stress on the lake ecosystem. Lake Elizabeth was originally part of the Loddon River flood plain but then was included in the local irrigation supply system. Following this, the lake was removed from the irrigation system and became a terminal lake (Delany 2004). As a result, its salinity has gradually increased to be over 40,000 EC during January 2007 Figure 5: Cockatoo Lagoon. — well exceeding levels at which aquatic biota are adversely affected (Neilsen et al. 2003). Water quality

guideline values were also triggered for total nitrogen. Longmore Lagoon met all water quality guideline Both macroinvertebrate samples met the guidelines values except turbidity, which was only slightly for family richness for high salinity lakes (five or more (3 NTU) above the guideline value. Biological families). Habitat quality and modification scores were guidelines were met for family richness but not the moderate. VLAKES index, implying that, despite being a diverse Like Lake Elizabeth, Lake Cullen (Figure 6) has ecosystem, some sensitive families may be absent undergone large hydrological changes since European from the system due to human disturbances. These settlement. Algal blooms have frequently been an disturbances may include altered hydrological regimes issue affecting water quality in this lake and a previous due to irrigation needs and the impacts from the study indicated that the lake is a stressed ecosystem surrounding agricultural land. (DNRE 2001). Lake Cullen triggered one water quality The hydrological flows and natural environment of guideline — pH. Both macroinvertebrate samples met Lake Boga have undergone significant alterations the guidelines for family richness and lake habitat since European settlement. Lake Boga was once quality and modification scores were moderate. included in the Torrumbarry irrigation system. More recently it has been managed to maximise environmental and conservation values, in recognition

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Southern lakes Barracouta and Dock Inlet (see section on eastern coastal Lakes). The lake habitat quality assessment Two riverine flow-through lakes were sampled, Lake score was high, as expected of relatively unmodified Elizabeth in the south-west of the state, and Thurra lakes located within a national park. However, the lake Swamp in the east. Lake Elizabeth in the Great Otway habitat modification score rated moderate and National Park in Southern Victoria (Figure 1) was indicated threats due to human activities. These formed when a landslide blocked the east branch of threats include recreational activities such as camping the Barwon River in 1952. and boating, and also moderately intensive land uses Lake Elizabeth had excellent environmental condition within the catchment, including forestry. and did not trigger any of the water quality or Lake Craven, located in south-western Victoria near biological quality guideline values. This lake is a site of the Great Otway National Park, triggered three of the national significance (DPI 2007) and the protection of seven water quality guideline values — DO, EC and pH — the biologically diverse and high-quality environment and all biological quality guideline values were of Lake Elizabeth is important. triggered. The lake habitat quality was moderate and the lake habitat modification score was poor. Identified threats included cattle grazing and recreation, which may be contributing to the poorer environmental condition of the lake. The high salinity in this lake (compared to the other coastal dune lakes) may be contributing to the low biological scores. Lake Bridgewater is located along the far west coast of Victoria. All water quality guideline values were met except pH, but both biological quality guideline values were triggered. Scores were moderate for the lake habitat quality assessment but poor for lake habitat modification. The lake has a number of in-lake threats, which may be contributing to the low biological scores, including boating and water sports, as well as surrounding land- Figure 6: Lake Cullen. use threats such as grazing.

Thurra Swamp is located in the Croajingolong National Park in far eastern Victoria and has been recognised as a special protection area because of its valuable habitat for fauna species (Croajingolong National Park Management Plan, 1996). Thurra Swamp triggered only one of the water quality guideline values — dissolved oxygen. The surrounding- lake and in-lake habitat was of good quality and supported good macroinvertebrate diversity. Minimal lake habitat modification and few catchment threats were identified. 2. Sand dune lakes Western coastal lakes Figure 7: Lake Elusive. Lake Monibeong is located in the Discovery Bay Eastern coastal lakes Coastal Park in far western Victoria. Lake Monibeong triggered only one of the seven water quality guideline Of the eastern sand dune lakes, Lake Elusive (Figure values — total nitrogen. The reason for the high 7) met all water quality guideline values, and both the nitrogen level is unclear and may either reflect land- lake habitat quality assessment and lake habitat use impacts from the surrounding catchment, modifications scores were excellent, indicating good naturally nitrogen-rich groundwater inputs or a habitat — as expected of lakes located within national combination of both. parks. Macroinvertebrate diversity was lower than Macroinvertebrate diversity was high and comparable expected and the biological quality guideline value for to that of the eastern sand dune lakes such as Lake number of families was triggered.

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The water at Lake Elusive was coloured due to tannins As the drying phase continues, water quality and leachate from organic matter, which is known to deteriorates and nutrient and salts become more reduce primary production by reducing light concentrated with decreasing water volume. Drought penetration and therefore algal and macrophyte conditions can exacerbate the effects of the drying growth. These tannins may limit food sources and phase. Salinity levels continue to rise as the lakes dry, habitat for macroinvertebrates and therefore reduce causing extreme stress for the flora and fauna that macroinvertebrate diversity. live in the lakes. Eventually the tolerance levels of many organisms are exceeded and diversity Timms (1973) previously found Lake Elusive to be decreases, as only tolerant species survive (as shown particularly low in macroinvertebrate diversity and by the recent large eel deaths in the Western District abundance compared to other freshwater lakes. It is Lakes). likely that low diversity and productivity is the natural condition for this lake. A locally specific biological Lake Tooliorook (Figure 9) triggered all water quality guideline value could be developed for this lake. guideline values except turbidity. The only biological guideline value for this lake type, number of families, Lake Barracouta is part of the largest continuous was met for both samples. The lake habitat quality coastal wetland in Croajingolong National Park, in far assessment score was moderate and the lake habitat eastern Victoria. Lake Barracouta had good lake modification score was poor, indicating significant habitat quality and no human impacts or modifications threats to Lake Tooliorook from human activities. to the lake habitat were identified. Macroinvertebrate These human threats, in combination with the drought, diversity was high and the VLAKES score met the may be contributing to the observed poor water guideline value. quality. In terms of water quality, total nitrogen and dissolved oxygen just triggered the guideline values. An investigation into the reasons for this result — whether naturally occurring or due to human activity — would assist in protecting this unique ecosystem. Dock Inlet (Figure 8), located in Cape Conran Coastal Park in far eastern Victoria, also had excellent environmental conditions. It triggered only one guideline value — chlorophyll-a — and the measure was only slightly greater than the guideline value.

Figure 9: Lake Tooliorook.

Lake Bolac triggered all water quality guideline values except DO. The only biological quality guideline for this lake type, number of families, was met for both samples. The habitat quality assessment was moderate and habitat modification score was poor, indicating significant threats to the lake ecosystem from human activities. Figure 8: Dock Inlet. It is expected that water quality and biological quality In summary, Dock Inlet, Lake Elusive and Lake may be improved when more water enters the system. Barracouta are unique coastal lake ecosystems with At the time of sampling the maximum water depth was excellent environmental values that should continue to 30 cm. In part, these water quality results reflect the be protected. natural wetting and drying cycle of shallow inland lakes. 3. Shallow inland lakes Lake Modewarre only met three of the water quality Shallow inland lakes such as Lake Bolac, Lake guideline values — dissolved oxygen, turbidity and Modewarre, Lake Tooliorook and Mill Swamp chlorophyll-a. The family richness guideline was experience a natural wetting and drying cycle, driven triggered. Lake habitat quality assessment and habitat by rainfall and evaporation. modification scores were both poor, indicating

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significant human-induced threats that may be contributing to the current environmental condition of Lake Modewarre. triggered all water quality and biological quality guideline values. Lake habitat quality was also poor and highly modified due to multiple threats, including a sewage treatment plant, quarry, grazing and plantations. The prolonged drought, combined with the large range of impacts from human activities within and surrounding the lake, are the likely causes of the poor water quality, which has in turn also impacted on the biological condition of the lake. Mill Swamp triggered two of the seven water quality guideline values: dissolved oxygen and chlorophyll-a. Mill Swamp had the most diverse macroinvertebrate Figure 10: Lake Surprise. fauna of all the shallow inland lakes of western Victoria. Despite this, it triggered all biological quality guideline values. Lake Purrumbete is a volcanic maar lake located in western Victoria. It triggered four of the seven water The high score for lake habitat quality assessment, quality guideline values – total nitrogen, total combined with the low lake habitat modification score, phosphorus, dissolved oxygen and pH. indicates that Mill Swamp is an environmentally valuable lake ecosystem that would flourish during the Elevated nutrient levels may be a result of agricultural wet years. Further monitoring would enable a better practices within the catchment, as the lake acts as a understanding of the resilience and robustness of sink for nutrient run-off. Nitrogen appears to be the healthier lake ecosystems. limiting nutrient in this lake system, whereas generally phosphorus is the limiting nutrient in lakes. High pH 4 Deep inland lakes may reflect the natural chemistry of this system. Lake Surprise (Figure 10) is located in the crater of Further investigation may help in understanding Mount Eccles, in Mount Eccles National Park in whether triggering of the guideline values is a result of western Victoria. It is a volcanic caldera lake with natural processes within the lake ecosystem or of geological features of national significance. catchment activities. Although the lake triggered three of the seven water The lake habitat quality assessment score was good quality guideline values (total nitrogen, dissolved and indicative of the diverse and abundant oxygen and pH), biological quality was excellent, with macrophytes within the lake ecosystem. However, the good macroinvertebrate diversity and a high VLAKES lake habitat modification score was ‘very poor’ and score. signifies many human-induced threats to the lake. All biological quality guideline values were triggered for The lake habitat quality assessment score was good; Lake Purrumbete. however, the lake habitat modification score identified some catchment threats to environmental quality, Macroinvertebrate diversity was lower than expected, including recreation and grazing. These threats should considering the quality of in-lake habitat. Lake be monitored to reduce possible adverse impacts on Purrumbete supports a multi-species fishery. The lake the lake ecosystem, in order to protect this significant is regularly stocked with brown trout, rainbow trout natural environment. and Chinook salmon and the redfin population has been reported to be increasing (DPI 2008). Predation by fish may be influencing macroinvertebrate diversity within the lake. Lake Bullen Merri (Figure 11), a volcanic maar lake in the western district of Victoria, is naturally saline (approximately 15,500 EC). No guideline value for electrical conductivity has been set for this naturally saline lake type. Four of the six guideline values were triggered for Lake Bullen Merri — total phosphorus, total nitrogen, pH and turbidity. As in Lake Purrumbete, nutrient levels in Lake Bullen Merri are likely to be a reflection

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of agricultural practices within the catchment. The pH pristine) and a habitat quality score (again 1 to 10, with in this lake is reflective of the geology of the western 1 being very poor and 10 being excellent habitat). district and a locally specific guideline value may be The two lake habitat indices were significantly appropriate.. All biological quality guideline values correlated with the expert panel measures, indicating were triggered for Lake Bullen Merri. that the indices provide an objective method for As the salinity of this lake is over 10,000 EC, the assessing lake condition (Figures 12 and 13). Guidelines suggest that between five and 12 Both indices were also compared to Index of Wetland macroinvertebrate families would be expected. Condition (IWC) scores for 13 lakes in the Western However, a maximum of only two macroinvertebrate District (EPA Victoria, unpublished data). The LHMS families was collected. In comparison, previous index was significantly correlated with the total IWC sampling campaigns in Lake Bullen Merri over the score (R2 = 0.62), while the LHQA index showed a period 2004—06 collected four to five weak relationship (R2 = 0.27), which was not macroinvertebrate families. This reduction to two statistically significant. families in the 2007 snapshot would not be picked up in a once-off sampling event and highlights the value As the IWC is based on threats (or modifications) to of regular monitoring in understanding trends within wetlands, the significant correlation with the lake an ecosystem. habitat modification score (LHMS) is to be expected. Similarly, the weak correlation between the IWC and Poor in-lake habitat may be contributing to the the lake habitat quality assessment (LHQA) is also to consistently poor macroinvertebrate diversity in Lake be expected, as the LHQA measures attributes not Bullen Merri. The decline in biodiversity may indicate included in the IWC. other ecosystem changes or increased stressors on the lake that should be investigated further.

60 R2 = 0.82

40

LHMS 20

0 12345678910 Expert panel 'reference' score

Figure 12: Correlation of the LHMS with the expert panel reference score.

Figure 11: Lake Bullen Merri.

PERFORMANCE OF THE INDICATORS 80 R2 = 0.56 In addition to providing a baseline assessment of the 60 condition of Victorian lakes ecosystems, this snapshot study allowed the indicators and guideline values 40 detailed in the Environmental quality guidelines for LHQA Victorian lakes (EPA 2009) to be trialled. Data from 20 the snapshot study was used to refine the guideline values prior to their finalisation. The final guideline 0 values were used in the assessments of the lakes in 12345678910 this report. Expert panel habitat quality score The habitat indices derived from the LHS field assessment sheets (LHMS and LHQA) were compared to an expert panel score of lake condition. Participants Figure 13: Correlation of the LHQA with the expert on the panel discussed each lake and gave it a panel habitat quality score. reference score (ranging between 1 and 10, with 1 being a highly modified environment and 10 being near-

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Generally, biological guidelines were triggered for when interpreting results. Assessments based on lakes that had high modification scores and low chlorophyll-a should always consider local conditions. habitat quality scores. For freshwater lakes, the VLAKES index correlated well with LHQA (Figure 14) SUMMARY but showed a weak relationship with LHMS (Figure 15). Family richness guideline values were also often This report has provided a baseline snapshot of triggered in lakes with poor water quality and poor environmental condition across a range of Victorian habitat. Many saline lakes in the later stages of drying lakes. Lakes in agricultural and urban settings were triggered the guideline values for the family richness clearly more stressed than lakes surrounded by forest, index, suggesting that the index is responding to the national park or coastline. Many of these poorer prevalent drought conditions. quality lakes were located in the Western District. In particular, the shallow were found to be in poor condition due to the combined 6 R2 = 0.36 effects of drought and a range of human-induced impacts. 5 The eastern coastal dune lakes (Dock Inlet, Lake Barracouta and Lake Elusive) and the two riverine 4 flow-through lakes (Lake Elizabeth in the Otways and Thurra Swamp in east Gippsland) were found to be in excellent condition. VLAKES score VLAKES 3 The effects of drought and climate change on reducing lake quality are evident in this snapshot report. Lakes 2 in later stages of drying triggered guideline values 25 35 45 55 65 more frequently than those with more water, despite LHQA score similar human pressures. The Kerang lakes are an example of this, with Lake Boga (sampled in the drying stage) triggering all but one guideline value, compared Figure 14: Correlation of the VLAKES scores with with other lakes in the district used as irrigation LHQA scores for freshwater lakes. storages (for example, Kangaroo Lake, which met six out of the 10 guideline values).

6 A snapshot approach is insufficient for comprehensive R2 = 0.14 condition assessment, particularly for lakes that are naturally hydrologically variable (such as the Hattah 5 lakes or shallow Western District lakes). This study has highlighted the need to understand the different 4 ecosystem responses in different lake types and use

VLAKES score appropriate sampling regimes tailored to suit the lake 3 type, as recommended in the Guidelines. 0 1020304050 The recent development of the Environmental quality guidelines for Victorian lakes has provided the LHMS score benchmark against which this snapshot assessment of the condition of our lakes could be performed. Figure 15: Correlation of the VLAKES scores with Additional monitoring will provide further information LHMS scores for freshwater lakes. to improve and refine the Guidelines.

Water quality guidelines were generally triggered for lakes with high modification scores, implying that surrounding land use and in-lake pressures are directly affecting water quality. The chlorophyll-a water quality guideline, however, varied in effectiveness as an indicator. For example, the Hattah lakes are considered to be in good condition but had high chlorophyll levels, which normally indicates a stressed ecosystem. These lakes are known to naturally experience algal blooms following refilling after extended dry periods. This highlights the need to consider the nature of the specific lake ecosystem

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REFERENCES

ANCA 1996, A Directory of Important Wetlands in EPA Victoria 2009, Environmental quality guidelines . Australian Nature Conservation Agency, for Victorian lakes (EPA publication 1302), . Canberra. EPA and MDFRC 2008, Implications of pumping and Delany A 2004, Lake Elizabeth Surface-Groundwater ponding water on water quality and the development Interactions. Summary of Dr Phillip Macumber’s of diverse aquatic ecosystems — Intervention Report: A Review of the Hydrology of Lake Elizabeth monitoring of the Hattah Lakes Icon Site 2006/07. and Lake-Groundwater Interactions November 2002. Report to the Murray-Darling Basin Commission. DPI Environmental Protection Agency Victoria and Murray- Department of Natural Resources and Environment Darling Freshwater Research Centre. (DNRE) 2001, Lake Cullen Feasibility Study and Herpich MA 2002, The Nutrient and Phytoplankton Operational Guidelines. Prepared in association with Status of Lakes Purrumbete and Bullen Merri, Western Moore Environmental Consulting & Lloyd Victoria. Environmental Consultants. Index of Wetland Condition Assessment of Wetland Department of Primary Industries Victoria (DPI) 2008, Vegetation Update, Department of primary Industries, Angling Waters of the Otway Basin 35, accessed Victoria. accessed 28/4/2008, 28/4/2008, www.dpi.vic.gov.au/angling/35- www.dpi.vic.gov.au/dpi/vro/egregn.nsf/pages/eg_lf_sit Otway/Basin%20TEMPLATE%20Waters.htm#Purrum es_significance_8822_6 bete Lugg A, Heron S, Fleming G, O’Donnell T 1989, Department of Primary Industries Victoria (DPI) 2007, Conservation Value of the Wetlands in the Kerang Victorian Resources Online: Lake Elizabeth and Lakes Area. Report to Kerang Lakes Area Working Landslide, accessed 28/4/2008, Group. 1. Department of Conservation Forests and www.dpi.vic.gov.au/DPI/Vro/coranregn.nsf/pages/cor Lands, Kerang Lakes Assessment Group. angamite_landform_lake_elizabeth. Rowan JS, Carwardine J, Duck RW, Bragg OM, Black Department of Sustainability and Environment (DSE) AR, Cutler MEJ, Soutar I, Boon PJ 2006, Development 2007, Index of Wetland Condition Methods Manual of a technique for Lake Habitat Survey (LHS) with Version 4, Melbourne. applications for the European Union Water Framework Department of Sustainability and Environment (DSE) Directive. Aquatic Conservation: Marine & Freshwater 2005a, IWC Conceptual framework and selection of Ecosystems, 16, 637–57 measures, Melbourne. Timms BV 1973, A limnological survey of the Department of Sustainability and Environment (DSE) freshwater coastal lakes of east Gippsland, Victoria. 2005b. Index of Wetland Condition Assessment of Australian Journal of Marine and Freshwater Research, Wetland Vegetation, Melbourne. 24, 1—20. EPA Victoria 2003a, Guidelines for Environmental Kelly MJ 1996, Wetland Management Strategy Lake Management: Rapid bioassessment methodology for Elizabeth Kerang. Department of Conservation and rivers and streams, accessed 28/4/2008, Natural Resources, Melbourne. epanote2.epa.vic.gov.au/EPA/Publications.nsf/PubDoc sLU/604.1?OpenDocument EPA Victoria 2003b, Risk assessment approach — Ecosystem protection, accessed 28/4/2008, epanote2.epa.vic.gov.au/EPA/publications.nsf/2f1c262 5731746aa4a256ce90001cbb5/74d82f9e5178574eca 256b19000db06e/$FILE/790.1.pdf EPA Victoria 2004. Guidelines for Environmental Management — Risk-based assessment of ecosystem protection in ambient waters (EPA publication 961), Melbourne. EPA Victoria 2007. Findings of western Victorian lakes eel death investigation, accessed 28/4/2008, epanote2.epa.vic.gov.au/EPA/Publications.nsf/2f1c262 5731746aa4a256ce90001cbb5/e6297aab90f665c1ca2 5719c00096808/$FILE/1114.pdf

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APPENDIX 1: ASSESSMENT OF EACH LAKE AGAINST GUIDELINE VALUES

Green shading indicates the guideline value was met, red indicates that the guideline value was not met. Coastal dune — eastern Biological indicators Habitat indicators Water uality indicators Number of Number of Lake VLAKES (combined DO (%) EC @ pH Turbidity Chl-a Families Families LHQA Rating LHMS Rating Total P Total N samples) range 25oC range (NTU) (µg/L) sample 1 sample 2 Guideline values 15 15 4.7 >45 Good 0–15 Good 30 500 80-120 1500 6-7.5 5 5 Dock inlet 19 20 5.32 43.3 Moderate 0 Good 13 461 93 578 7.0 3.3 7.6 Lake Barracouta 18 20 4.90 47.0 Good 0 Good 7 518 73 666 6.5 2.2 2.6 Lake Elusive 13 14 5.84 47.3 Good 2 Good 14 347 92 413 6.7 0.6 4.7

Coastal dune — western Guideline values 15* 15* 4.7 >45 Good 0–15 Good 30 500 80-120 1500 6.5-8.5 5 5 Lake Craven 12 (13) 12 (13) N/A - saline 36.8 Moderate 42 Poor 5 164 144 8148 9.1 1.1 1.8 Lake Monibeong 19 23 4.50 45.0 Good 16 Moderate 5 726 110 1093 7.4 0.6 1.3 Lake Bridgewater 6 7 4.28 32.7 Moderate 36 Poor 10 386 120 1204 8.9 0.4 2.7

Shallow inland — outflow Guideline values 15* 15* 4.3^ >45 Good 0–15 Good 100 1500 80-120 N/A 6.5-8.5 15 10 Lake Boga 8 (13) 11 (13) N/A — saline 20.3 Poor 46 Very Poor 180 3914 133 4350 8.6 42.0 9.3 Lake Bolac 5 (5) 7 (5) N/A — saline 31.2 Moderate 42 Poor 250 8307 118 43889 9.0 37.0 13.0 Lake Modewarre 4 (5) 5 (5) N/A — saline 26.4 Poor 44 Poor 220 13009 115 54430 10.0 3.1 2.4 Lake Toolirook 6 (5) 5 (5) N/A — saline 36.8 Moderate 38 Poor 240 6303 53 39031 9.5 1.6 16.2 Mill Swamp 10 12 3.65 42.7 Moderate 10 Good 67 3504 152 1742 8.6 6.2 12.8 Lake Colac 8 (12) 8 (12) N/A — saline 24.1 Poor 56 Very Poor 830 3946 75 12355 8.7 198.0 18.4 ^ VLAKES is not assessed for lakes exceeding EC of 3,000 µs/cm. * If the EC of a site exceeded 3,000 µs/cm, the guideline value for number of families have been adjusted as follows: 3,000 – 10,000 µs/cm, the guideline value is 13; 10,000—35,000 µs/cm, the guideline value is 12; for >35,000 µs/cm, the guideline value is 5. The adjusted guidelines for the number of families for individual lakes are shown in brackets in the table.

12 A SNAPSHOT OF THE ENVIRONMENTAL CONDITION OF VICTORIAN LAKES

Riverine — floodplain Biological indicators Habitat indicators Water quality indicators Number of Number of Lake VLAKES (combined DO (%) EC @ pH Turbidity Chl-a families families LHQA Rating LHMS Rating Total P Total N samples) range 25 °C range (NTU) (µg/L) sample 1 sample 2 Guideline values 15* 15* 4.3^ >45 Good 0-15 Good 100 1500 80-120 N/A 6.5-8.5 15 10 Cockatoo lagoon 15 20 4.09 44.5 Moderate 40 Poor 15 364 110 79 6.1 0.8 1.8 Kangaroo lake 15 11 3.52 31.9 Moderate 44 Poor 290 1460 109 218 8.1 118.0 3.1 Lake Arawak 18 18 3.88 34.0 Moderate 0 Good 590 2303 132 274 8.0 10.0 10.1 Lake Brockie 13 15 3.75 39.3 Moderate 0 Good 780 4808 105 271 8.1 40.3 45.9 Lake Cullen 15 (12) 12 (12) N/A — saline 32.8 Moderate 20 Moderate 17 1203 118 11650 9.7 0.3 1.1 Lake Elizabeth (Kerang) 7 (5) 5 (5) N/A — saline 35.6 Moderate 24 Moderate 75 3206 110 40480 8.5 0.7 0.9 Lake Hattah 16 23 4.00 38.3 Moderate 0 Good 250 4507 236 285 10.4 85.0 19.4 Lake Lockie 12 21 4.31 44.5 Moderate 0 Good 240 4204 183 210 10.1 70.3 13.6 Lake Mournpall 9 8 3.92 41.8 Moderate 0 Good 500 1965 112 199 7.3 10.1 6.9 Lake Yerang 18 13 4.36 43.7 Moderate 2 Good 140 2106 144 200 9.9 50.0 5.8 Longmore Lagoon 16 17 4.05 41.0 Moderate 36 Poor 37 303 102 58 6.9 18.0 3.6 Reedy Lake 13 19 3.83 31.5 Moderate 36 Poor 81 484 108 122 9.2 109.0 5.2

Riverine — flow-through Guideline values 15 15 4.7 >45 Good 0-15 Good 30 500 80-120 1500 6.5—8.5 5 5 Lake Elizabeth (Barwon) 21 28 5.00 47.6 Good 4 Good 6 236 108 167 8.2 0.6 2.1 Thurra swamp 17 17 5.00 59.0 Good 2 Good 23 415 57 237 7.1 1.0 4.2

Deep Inland — fresh Guideline values 15 15 4.30 >45 Good 0-15 Good 30 500 80-120 15006.5—8.5 5 5 Lake Surprise 20 22 4.96 44.6 Moderate 22 Moderate 16 789 123 703 9.0 2.2 2.4 Lake Purrumbete 13 9 4.06 51.1 Good 48 Very Poor 92 675 139 826 8.7 0.2 1.4

13 A SNAPSHOT OF THE ENVIRONMENTAL CONDITION OF VICTORIAN LAKES

Deep Inland — saline Lake Biological indicators Habitat indicators Water quality indicators Number of Number of VLAKES (combined DO (%) EC @ Turbidity Chl-a families families LHQA Rating LHMS Rating Total P Total N pH range samples) range 25 °C (NTU) (µg/L) sample 1 sample 2 Guideline values 15* 15* N/A^ >45 Good 0-15 Good 30 500 80-120 N/A 6.5—8.5 5 5 Lake Bullen Merri 1 (12) 2 (12) N/A — saline 29.7 Poor 44 Poor 96 3242 85 15658 9.1 21.0 2.9 ^ VLAKES is not assessed for lakes exceeding EC of 3,000 μs/cm. * If the EC of a site exceeded 3,000 µs/cm, the guideline value for number of families have been adjusted as follows: 3,000—10,000 µs/cm, the guideline value is 13; 10,000—35,000 µs/cm, the guideline value is 12; for >35,000 µs/cm, the guideline value is 5. The adjusted guidelines for the number of families for individual lakes are shown in brackets in the table.

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