22 CENTRAL REGION SUSTAINABLE WATER STRATEGY /CHAPTER 1 River and Aquifer Health

Rivers naturally have variable flow regimes reflecting the rainfall and Importance of flow for rivers run-off within their catchments. This includes low flows during summer European settlement and the associated landscape changes together with small freshening flows occurring periodically and higher winter with our reliance on rivers for water supply in the Central Region has flows including bank-full flows and floods of adjacent land. Each of taken its toll and some are in poor or very poor condition. Some of these components of the flow regime plays an important role in the these rivers are heavily utilised for consumptive purposes and in some ecology of the river, see Figure 3.1. For example, high flows stimulate cases have only about half of their natural flows, which becomes even fish breeding and maintain estuary openings. Similarly, groundwater less in drought years. Some of the catchments that these rivers flow can provide base flows in summer to maintain fish refuges. Floods in through are greatly modified by a combination of water extraction spring regenerate floodplains and wetlands, and replenish the river urbanisation, clearing of native vegetation, draining of wetlands and channel. Water extraction can change these crucial flow components pollution from adjacent land. with negative effects on the ecology of the system. Several rivers in the Central Region are not so heavily used and still retain 70% to 90% of their natural flows (see table 3.1). However, even in these rivers, this is no guarantee of environmental health. In many cases, these rivers are showing signs of environmental damage due to major changes in the pattern of flows (i.e. flow regime) and/or broader catchment changes.

Figure 3.1 Importance of the pattern of flow to the health of a river

Freshes Bankfull Overbank Flow Help Maintain or improve water qaulity Helps with sediment movement and channel maintenance Maintains floodplain and wetland connectivity

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Low Flow Cease to Flow High Flow Connects inter-stream habitats Dries out habitats - important for some ecological processes. Allows for fish migration.

Low Flow Cease to Flow High Flow CENTRAL REGION SUSTAINABLE WATER STRATEGY / STRATEGY WATER CENTRALSUSTAINABLE REGION

23 In undertaking these scientific studies, some of the constraints under Assessing the flow needs of our rivers which these river systems operate are built into the final environmental In 2002, the Victorian Government commissioned a review of flow recommendations. For example, overbank flooding is not environmental flow assessment methodologies across the world to included in the Lower Yarra, Werribee, Barwon and Maribyrnong rivers develop a ‘best practice’ that could be applied to Victorian rivers. The because of urban development on these floodplains. resultant approach – the FLOWS method - is now the standard in Table 3.2 provides estimates of the additional volume of water required for assessing the flow needs of rivers in water allocation decisions. to meet the full environmental flow recommendations for each of the The FLOWS method is applied to rivers where further water extraction key rivers in the Central Region. These have been calculated under is being considered to determine whether and how much additional full use of consumptive entitlements and current operating and water water can be taken without further environmental damage. It is also harvesting rules. applied to rivers identified as flow-stressed in regional river health This confirms that many rivers in the Central Region are flow stressed, strategies to identify how much additional water is required to sustain which is impacting on their environmental condition. Decisions on the environmental values of the river. These regional river health whether to return water to these rivers and how much, will take into strategies have been prepared by catchment management authorities account environmental benefits, the impacts on consumptive users in consultation with their broader communities. and any other costs. Scientific studies using the FLOWS method have now been Appendix 3 provides a detailed reach-by-reach breakdown for each completed for all the key rivers in the Central Region (see Table 3.1), river, of the compliance with the flow regime under full consumptive except for the , which will be completed later this year. use with the scientific recommendations (SKM 2005). In the FLOWS method, teams of independent scientists determine the flow components required to maintain and where necessary, enhance environmental values with a high probability of success. As part of the process, community advisory groups are established for each river to provide local knowledge and advice, particularly on environmental objectives and values. The Government acknowledges the extensive time, effort and valuable input these groups have put into each study.

Table 3.1 Independent scientific studies on environmental water requirements completed for rivers in the Central Region River Scientific Environmental Flow Studies Gellibrand Assessment of Environmental Flow Requirements for the , Draft Recommendations Revision B, Earthtech, January 2006. Barwon/Leigh Environmental Flow Determination for the : Final Report – Flow Recommendations, Lloyd Environmental Pty Ltd, Ecological Associates Pty Ltd, and Fluvial Systems Pty Ltd, October 2005 Moorabool An Assessment of Water Use and Environmental Flow Requirements for the - Moorabool River Water Resource Assessment. Sinclair Knight Merz, 2004 Werribee The Environmental Water Needs of the : Final Report – Flow Recommendations, Ecological Associates Report BN001-3D, September CHAPTER 3 CHAPTER 2005 Maribyrnong Assessment of Environmental Flow Requirements for the , Final Recommendations – Draft for comment, Revision B, Earthtech, January 2006 Yarra Determination of the Minimum Environmental Water Requirements for the , Final, Sinclair Knight Merz, December 2005 Latrobe Assessment of Environmental Flow Requirements for the , Final Recommendations Revision C1, Earthtech, January 2006 Thomson/Macalister Environmental Flow Options for the Thomson and Macalister Rivers, Final Report - Conclusions and Recommendations. The Thomson Macalister Environmental Flows Task Force February 2004 Gippsland Lakes Environmental Study: Assessing options for improving water quality and ecological function, CSIRO, South , 2001 CENTRAL REGION SUSTAINABLE WATER STRATEGY / STRATEGY WATER CENTRALSUSTAINABLE REGION

24 Table 3.2 Estimated addition required to the environmental flow regime10 to meet all the recommendations determined in the independent scientific studies River Estimated addition (ML/year) 1 Yarra 20,000 Werribee 14,500 Maribyrnong 6,900 /Tarago To be determined Latrobe To be confirmed 2 Thomson/Macalister 47,000 Barwon/Leigh 4,700 Moorabool 20,000 Gellibrand n/a as current flows are sufficient Total 113,100 1. These estimates are on the basis of the full use of entitlements and are long-term average flows. This is an approximation only assuming current operating and harvesting rules remain unchanged. It is subject to further refinement over time as our understanding of delivering environmental water reserves improves 2. This is to be confirmed pending the outcomes of a review of the environmental flow study by the Technical Audit Panel

Outlined below are the key findings from each environmental flow riparian vegetation is encroaching on the river channel. Reduced study and a summary of how well the full scientific recommendations freshes are affecting water quality and cause sediment to build u determined in the studies compare with the flow regime associated in the pools. Lack of overbank flow means that wetlands (eg Banyule with full use of consumptive entitlements. Complete environmental wetlands) are now watered less often. However, it is recognised that flow study reports are available at www.dse.vic.gov.au/riverhealth/ reinstating overbank flows, including the lower Yarra floodplain, would not be desirable due to impacts on urban centres. It may be possible Yarra River to undertake works to provide water to specific wetlands.

The Yarra River is an icon with high conservation, social and economic The Yarra estuary, although highly modified, plays a critical part in the values. A combination of flow and non-flow related issues influence river’s health. A number of native fish species, including the threatened the condition of the Yarra River and its tributaries. While the overall Australian grayling, need to migrate between fresh and estuarine or condition through the upper and mid reaches remains good, some marine waters as part of their life-cycle. Processes occurring in the elements of the flow regime under full use of consumptive entitlements estuary are strongly linked to interactions between freshwater inflows are insufficient to support important environmental values. For the from the Yarra River and tidal movement. most part, this is related to a reduction in the number and duration In general, maintaining the existing flow regime, with some of fresh and high flow events that would provide cues for Australian improvements to the low flows and summer and winter high flows

grayling spawning, flush sediments from benthic habitats, freshen and freshes in the mid to lower Yarra together with complementary 3 CHAPTER pools and inundate wetlands. works (eg replanting riparian vegetation and reducing pollution from The Upper Yarra Reservoir, constructed in the late 1950s, rarely spills stormwater) would protect the important values of the Yarra River. and as a consequence pools in the Yarra River below the reservoir It is estimated that the environmental flow regime would need to be have been infilled with sediment, reducing habitat availability for macro enhanced by about 20,000 ML to meet the scientific environmental invertebrates and fish, particularly river blackfish. A minimum flow of flow recommendations. 10 ML/d released from Upper Yarra Reservoir maintains a reduced but relatively healthy channel. Latrobe River Downstream of Warburton the health of macro invertebrate and fish The Latrobe River has significant environmental, social and economic communities improve rapidly with increased tributary inflows and values. The river’s condition is good in the upper reaches but poor in habitat availability, although reduced high flow events means that the lower reaches due to extensive channelling in the past. CENTRAL REGION SUSTAINABLE WATER STRATEGY / STRATEGY WATER CENTRALSUSTAINABLE REGION

25 The scientific study determined that in the Latrobe River the majority It was estimated in 2004 that the environmental flow regime in the of the flow components are inadequate below the Latrobe/ Thomson and Macalister rivers would need to be enhanced by 47,000 junction. For example, reduced summer and winter low flows and ML to meet the scientific environmental flow recommendations. summer and winter freshes affect riparian vegetation, migration and After a community consultation process, the Government agreed to spawning flows and instream habitat for native fish. The lower Latrobe provide 25,000 ML to meet critical environmental flow requirements. is heavily channelled and reinstatement of the original river meanders In late 2005, 10,000 ML was provided as an environmental entitlement will change the volumes required to reinstate these flow components. in Thomson Reservoir and works are being implemented to increase A review of the flow study is being undertaken by an independent flows in the . Technical Audit Panel to review its conclusions and recommendations.

The flow regime upstream of Willow Grove is largely natural due to the Maribyrnong River limited water taken from the river. The Maribyrnong River and tributaries support significant environmental and social values. The condition of the catchment varies Traralgon Creek and the suffer annual flow and low flow from good in the upper reaches to moderate to poor in the middle and reversal respectively. This is due to licensed discharges from industries. lower reaches. Improvements to the flow regime are required to protect environmental values that include river blackfish and Southern pigmy perch. Environmental flow regimes in this system were improved during the late 1990s to meet most of the recommendations from an early The Ramsar-listed Gippsland Lakes and a floodplain wetland system flow study. However, the drought has highlighted several issues and comprising the Gippsland Lakes Sale Common and Heart Morass are knowledge of river needs has improved since then. located downstream of the Thomson and Latrobe River . Flows have been reduced in this section of the river. However, in late The flow regime in Deep Creek, a major tributary, meets most of the 2005 the Government returned 10,000 ML to the scientific flow recommendations. Some components of summer flows which will benefit this reach of the river. The needs of this estuarine and winter flows however are insufficient to provide instream habitat section of the river have not been investigated at this stage. and protect environmental values including the Australian grayling and river blackfish. Results from a study of the Gippsland Lakes by CSIRO identified that the primary factor impacting on the health of the Gippsland A further major tributary, Jacksons Creek, is significantly impacted Lakes is the level of nutrients entering the lakes via major tributaries. by Rosslynne Reservoir which was constructed in 1973 for irrigation It was found that decreases in flow into the Lakes have similar, albeit and urban water supply. Summer and winter freshes and winter low proportionally smaller, impacts on algal blooms as increases in nutrient flows are inadequate, resulting in poor water quality, sediment build- loads. Further extractions from the rivers entering the Lakes may up affecting instream habitat for fish and macroinvertabrates, fish increase the severity of algal blooms, however it was recognised that migration and riparian and instream vegetation. Lower Jacksons this needs to be established with a greater degree of confidence Creek is less impacted due to tributary inflows from Riddells Creek. prior to further recommendations for management as this study was The flow regime in the freshwater reach of the Maribyrnong River primarily limited to examining algal blooms in the Gippsland Lakes. is generally good, however there is a small decrease in all flow It did not consider impacts to the ecological health of the Lakes as such. components with water quality being a key concern. It is estimated that the environmental flow regime would need to be It is estimated that the environmental flow regime would need to be enhanced to meet the scientific environmental flow recommendations,

CHAPTER 3 CHAPTER enhanced by an average of 6,900 ML to meet the current scientific however this remains to be confirmed by the Technical Audit Panel. environmental flow recommendations. Thomson/Macalister Rivers The Thomson and Macalister rivers are presently identified as flow stressed. Studies have found river health to be poor and/or degrading in sections of both systems, with issues such as reversal of the seasonality of flow, contraction of channels, a high prevalence of exotic vegetation and barriers to fish migration. However, both rivers retain very high environmental values. The Thomson is classified as a Heritage River in parts, and both rivers boast populations of the threatened Australian grayling and river blackfish. The bottom reaches of the Thomson and Macalister feed into Ramsar listed wetlands and the highly valuable Gippsland Lakes.

.In the Thomson River upstream of the Macalister River winter high flows and bank full flows are inadequate, impacting wetlands and

CENTRAL REGION SUSTAINABLE WATER STRATEGY / STRATEGY WATER CENTRALSUSTAINABLE REGION riparian vegetation.

26 Werribee River users. In the West Moorabool River, the average flows have been reduced from 36 ML/d to about 8 ML/d and the stream now ceases The Werribee River has areas of high conservation significance, to flow for more than 10% of the time, while this would be rare under and significant social and recreational value in the lower reaches natural conditions. and estuary. The condition of the river and its tributaries is variable, ranging from moderate condition in the middle reaches to poor in Despite such high percentage of flow extracted, the Moorabool does he lower reaches. have some environmental values worth protecting, although these are now not widespread. The Moorabool still contains sections of The hydrology of the Werribee River has been altered by storages intact stream side vegetation and provides habitat for the threatened causing regulation of flow. The most impacted sites are the Werribee Australian grayling and hairy anchor plant, Great egret and the River at Werribee, Coimadai Creek, Djerriwarrh Creek and Pykes platypus. The river also feeds the Barwon River near and the Creek with most flow components severely impacted. The flow internationally important . components impacted include summer and winter freshes, winter low flows and bank full flows through most of the system. Seasonal All components of the flow regime are inadequate, with the loss of flow reversal occurs below Pykes Creek and Melton Reservoirs due instream habitat, water quality and native spawning and migration. It is to irrigation releases. essential to initially enhance summer low flows and summer freshes in the mid to lower Moorabool River. These would maintain water quality The Werribee River provides an extensive system of diverse fish and habitat in the first instance. habitats which have been somewhat compartmentalised by several reservoirs and weirs. While some of the migratory habitat components Enhanced summer flows in the mid to lower reaches of the river are such as summer freshes have been lost, the river maintains the required for instream vegetation and the vegetation immediately next potential to support a large and diverse community of native fish. to the river.

Barriers to fish migration are an important feature of the Werribee It is estimated that the environmental flow regime would need to be River. The Werribee and Bacchus Marsh diversion weirs are classed enhanced by about 20,000 ML to meet the scientific environmental as moderately impacting fish migration, while Melton Reservoir flow recommendations. prevents the migration of fish between the sea and the upper tributaries. This is likely to prevent re-establishment of species such Barwon/Leigh Rivers as spotted galaxias and Australian grayling. The current condition of the Barwon River varies from good in the upper reaches, for example above West Barwon Reservoir, to poor Aquatic and reedy vegetation is affected by sustained high summer in the lower reaches. The scientific study identified a range of water flows caused by river regulation. The growth of these plants is limited dependent values including 44 species of freshwater and estuarine due to extended inundation of their habitat. fish including the Australian grayling (a nationally and State listed under Minor improvements are required to the flow regime upstream of the Environment Protection and Biodiversity Conservation (EPBC) Act Melton Reservoir while downstream of Melton Reservoir, reduced and the Flora and Fauna Guarantee Act (FFG) respectively) as well winter and spring base flows have affected the growing season as dwarf galaxias and Yarra pygmy perch, which are both FFG listed. of riparian vegetation. Below the Lower Werribee diversion weir, Other values identified include intact riparian vegetation communities flows are significantly less than those recommended by the study. through the gorge and waterbird populations which are These include high flow freshes, winter and spring base flows and internationally significant in Lake Connewarre.

summer and autumn low flows that are required to address the 3 CHAPTER The flow components in the Barwon and Leigh Rivers generally habitat requirements of native fish (including spawning and migration), are thought to be adequate, except for improvements required to macro invertebrates and vegetation. Complementary works such as better meet the needs of native fish. Dwarf galaxias require increases revegetation and provision of fish passage in the lower Werribee River in winter low flows below the West Barwon Reservoir. Migratory would protect important environmental values. fish, such as the threatened Australian grayling, require increases It is estimated that the environmental flow regime would need to in summer low flows and summer freshes in the Leigh and lower be enhanced by an average of 14,500 ML to meet the scientific Barwon Rivers to provide instream habitat and trigger spawning. environmental flow recommendations. Flows for the Ramsar-listed wetlands including Lake Connewarre are Moorabool River thought to be adequate. The Moorabool River is currently rated as having a very poor to poor It is estimated that the environmental flow regime would need to be environmental condition, and is classified as extremely flow stressed. enhanced by about 4,700 ML to meet the scientific environmental flow recommendations. The Moorabool River is considered one of the most heavily committed and therefore flow-stressed rivers in Victoria. As an example, in the drought year of 2003/04, the river received 14% of its natural flow, with the rest diverted for consumptive use by urban and rural water CENTRAL REGION SUSTAINABLE WATER STRATEGY / STRATEGY WATER CENTRALSUSTAINABLE REGION

27 Bunyip and Tarago Rivers Condition of our aquifers The Tarago River is considered to be ecologically healthy in its The health of our aquifers impacts the health of our rivers; groundwater upper reaches with good environmental values in the lower section. provides almost 50% of the baseflow in our waterways. The catchment sustains significant species such as the Australian grayling, river blackfish and platypus. Key environmental threats Table 3.3 outlines the current condition of aquifers in the Central Region. include weeds, stock access, sedimentation and sand slugs, lack It highlights aquifers under stress and over allocated. In the areas where of riparian vegetation and barriers to fish migration. groundwater has been over-allocated (Bungaree, Deutgam, Koo-Wee- Rup and central Gippsland aquifers), Water Supply Protection Areas The middle and upper reaches of the are in good (WSPAs) have been established under the Water Act, and committees condition, with high environmental values and many reaches appointed or proposed to develop management plans. considered ecologically healthy. Several significant species of native flora and fauna occur within the upper Bunyip River, including azure kingfishers and powerful owls. Key environmental threats include a lack of riparian vegetation and barriers to fish migration and other aquatic life.

Interim flow recommendations have been developed for the Bunyip and Tarago Rivers with detailed assessments of the needs of the rivers being undertaken this year.

Initial results from a 2004 The Department of Sustainability and Environment assessment indicate that summer and winter low flows are inadequate. In particular, both summer and winter freshes below Tarago Reservoir are required to provide instream habitat for native fish, including river blackfish, Australian grayling, dwarf galaxias and freshwater crayfish. Gellibrand River The Gellibrand River is essentially an unregulated river apart from a small storage on the West Gellibrand River. This storage feeds into Barwon Water’s water supply system for Geelong. As the storage is quite small, diversions are relatively minor compared with streamflow and so there are no significant environmental flow issues in this reach.

However there are a considerable number of licensed diversions in the basin for irrigation, which typically access water from the river in summer. While the total amount of water being extracted is not an issue, the timing of extractions coincides with the low flow which increases stress on instream biota such as river blackfish. CHAPTER 3 CHAPTER In addition, the Gellibrand River estuary and wetlands are key environmental assets. Flows in these systems are dependent on freshwater inflows from the river. The environmental flow requirements of the estuary have not been assessed but because the river is unregulated, it is highly likely that existing flows are sufficient. CENTRAL REGION SUSTAINABLE WATER STRATEGY / STRATEGY WATER CENTRALSUSTAINABLE REGION

28 Table 3.3 Current condition of aquifers with an indication of allocations exceeding sustainable yield Area Aquifer Groundwater level Potential for Volume allocated Comments trends groundwater level above sustainable to decline over next yield (ML) five years Cardigan Stable Low - Ballarat has applied for a licence, new area to be established. Bungaree Stable Low 0 Geelong Gellibrand Stable Low - Gerangamete Within plan limits1 Low - This is the source of Geelong’s groundwater supply. Licence enables 20,000ML in one year, 80,000ML over 10 years and 400,000 ML over 100 years. Jan Juc Stable Low - moderate - Subject to a detailed hydro-geological review to confirm the sustainable yield potential for aquifer recharge being investigated. Newlingrook Stable Low - This is included as an option for a new source of water for Geelong. Subject to a detailed hydro-geological review to confirm the sustainable yield. Inner West Deutgam Within plan limits1 Low 3,135 Groundwater management plan in place. Extractions are controlled to prevent seawater intrusion. Deep Werribee Lancefield Stable Low - Already used by Western Water to supplement Lancefield’s surface water supply. Merrimu Stable Low - Melbourne Boneo Stable Low Saline, new area with potential for geothermal resources Cut Paw Paw Stable Low - Potential for non-potable use, but needs an assessment of the risk of contamination from shallow aquifers underlying the Altona industrial area. Frankston Stable Low - Potential for non-potable water supplies from shallow unconfined aquifer in the sand belt. Kinglake Stable Low - There is a high level of surface water interaction with this fractured rock aquifer. Koo Wee Rup Within plan limits1 Low - Groundwater management plan in place. Moorabbin Stable Low - Potential for non-potable water supplies from shallow unconfined aquifer in the sand belt. Nepean Stable Medium 637 Wandin Yallock Stable Low - Gippsland Denison Within plan limits1 Low 5743 High use reflects public pumping entitlements to control salinity and water table levels. Leongatha Stable Low -

Moe Stable Low - Subject to a detailed hydro-geological review to confirm the sustainable yield. 3 CHAPTER Rosedale Declining High 12,971 Declining water levels are thought to be due to mine dewatering activities of the Latrobe Valley Coal Mines. Sale2 Declining Medium 7,893 Groundwater management plan to be established following technical review. Stratford2 Declining High - Declining water levels are due to mine dewatering activities of the Latrobe Valley Coal Mines and offshore oil and gas extraction. Wa De Lock2 Stable Low - Westernport Corinella Stable Low - Potential source for Westernport Water. 1. Fluctuating levels are managed through relevant groundwater plans. 2. While these aquifers are not strictly within the boundaries of the Central Region, they have been included as they are used by industries which are located in the region. CENTRAL REGION SUSTAINABLE WATER STRATEGY / STRATEGY WATER CENTRALSUSTAINABLE REGION

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