Snowy Advisory Committee

John Rodger is a Conjoint Professor at the University of Newcastle, CEO and Executive Director at FAUNA Research Alliance, and a Fellow at the Institute of Managers and Leaders. He has been involved in study of the reproductive biology of marsupials for all his career, with a particular focus on turning this basic science into new and better tools to conserve threatened marsupials and fertility-based controls for overabundant marsupials, including the brushtail possum in New Zealand. He led the only Cooperative Research Centre dedicated to innovation in marsupial conservation and management. His contributions were recognised by appointment as an Emeritus Professor in 2019.

‘I am a long-time companion to the unique Snowy Mountains, and am very pleased and honoured to be taking up this role. I look forward to working with the diverse members of the Snowy Advisory Committee in seeking opportunities for strategic improvements for flows in the Snowy and montane rivers that benefit not just the river environments but the rivers’ communities.’

‘I have had the wonderful opportunity to have lived at Marlo, near the mouth of the Snowy River, for the last 30 years.

‘I greatly appreciate the environment that I live in and this has motivated me to participate in community groups that are committed to the rehabilitation of the Snowy River.

‘The start of the environmental water releases and the first release of Australian bass by an Indigenous aquaculturist in the Snowy River are my fondest memories.’

Dr Doris Paton is a Monero–Ngarigo and Gunai woman. She is a specialised educationalist and researcher. She focuses on empowering others with knowledge to strengthen relationships and understanding. She is strongly committed to sharing her cultural knowledge of language and local history. Doris has a strong governance background and has held many positions on local, regional and national committees and boards.

She is currently a part-time Senior Lecturer at Monash University. Over many years, she has held management positions in Aboriginal education and training. She is a specialist curriculum advisor in Aboriginal curriculum and content. She educates the wider community through customised cultural competency training.

To be provided.

Dr Fiona Dyer is Associate Professor in Water Science with the Centre for Applied Water Science (CAWS), and the Institute for Applied Ecology (IAE), University of Canberra.  She is a freshwater research scientist with an active research program in environmental flows and eco-hydrology. For the past 20 years, Fiona has been involved in the design, implementation and monitoring of environmental flows in a range of riverine environments in south-eastern Australia.

Her research has contributed to the management of environmental flows from the upland rivers of the Murrumbidgee catchment to the lowland rivers of the Lachlan catchment. She has co-authored more than 50 peer-reviewed journal publications, 2 book chapters, 10 refereed conference proceedings and a wide variety of technical reports.

In addition to her research-led contributions to policy and practice, Fiona is actively involved in community natural resource management organisations in the region. She is currently an executive member and past chair of the Upper Murrumbidgee Catchment Network, a community-based cross-border network of agencies and groups responsible for natural resource management in the upper Murrumbidgee catchment, and she has a particular interest in environmental flows across the montane rivers.

Graeme Enders is a former Director in the Biodiversity, Conservation and Science Division of the Department of Climate Change, Energy, the Environment and Water. This role carried operational responsibility for the delivery of water to the environment in southern New South Wales, including the Snowy and montane rivers, where different groups within the department collaborated to manage the annual environmental flows with the advice of the SAC.

Graeme has a long association with the Snowy River, having contributed to achieving a balanced outcome for the river, for its communities and for the hydro company during its corporatisation. He also contributed to a recovery project to bring together NSW agencies with communities in anticipation of increased flows after that time. The SAC continues this important connection.

Graeme Dear has been a recreational fisher his entire life and has spent many years fishing the Snowy River for bass and other estuary fish. His interest in fishing led him to become the Chief Executive Officer (CEO) of the East Gippsland Catchment Management Authority (EGCMA), where his love of rivers and professional administration expertise aligned.

Graeme has been the CEO of the EGCMA for 18 years. The EGCMA is responsible for managing the health of the Snowy River in Victoria and provides advice on behalf of the Victorian Government on the health needs of the river and estuary.

The Snowy Advisory Committee (SAC) met via videoconference on 26 August 2024 to receive updates on several initiatives.

Trialling trigger flows: dam releases made in sync with natural water flow events

The NSW Department of Climate Change, Energy, the Environment and Water and Snowy Hydro are trialling delivering flows. This is different from the current practice, where the flows are planned well in advance. Implementing ‘trigger releases’ provides more flexibility in the management of environmental flows and aims to respond to natural cues created by rainfall events.

Previous triggered releases successfully mimicked natural flows in response to local rainfall. Following the successful first trigger release from Jindabyne Dam into the Snowy River in May 2024, another was provided in June 2024 to the upper Murrumbidgee River from Tantangara Dam. If natural rainfall cues occur, the next opportunity for potential trigger releases from Jindabyne and Tantangara dams is in Autumn 2025.

Macroinvertebrate research

Dr Andrew Brooks presented results from research conducted in the Snowy River and Montane streams. Macroinvertebrate (water bug) communities were monitored over 3 years to build on previous sampling work undertaken from 2000 to 2016. Macroinvertebrates are a major component in aquatic food webs and changes in flow regimes can affect these populations by altering food sources and habitat. The Snowy Scheme has dramatically changed the flow regime in the Snowy and Montane streams. Provision of environmental flows supports invertebrate species by mimicking natural flows, particularly high flows to help clean riverbed substrates. The monitoring shows improved flow regimes have shifted macroinvertebrate communities to be more like natural reference streams, with more species who prefer cleaner substrates flushed of sediment occurring in the samples.

Kayaking at Dalgety

Dalgety community member Peter Heeley presented to the SAC on the potential of a whitewater kayaking facility at Dalgety Weir which would require adapting flows for the operation of a wave formed via a modified weir. The committee discussed trade-offs and environmental implications that would need to be considered in changing flows to suit a kayaking facility. The water used in the Snowy has specific environmental objectives defined in the Snowy Water Inquiry Outcomes Implementation Deed (SWIOID), which dictate how the water may be used. The committee noted there may be opportunities where releases could be made that benefit kayakers without reducing environmental outcomes, but these may be limited. Further work needs to be carried out to determine the flow rates required and whether such flows could be provided without compromising environmental objectives The foreshadowed future review of the SWIOID may consider incorporating social values.

Exploring the Snowy River estuary

The Snowy Advisory Committee convened in May 2024 at Marlo in Victoria, where the Snowy River meets the Southern Ocean. The East Gippsland Catchment Management Authority hosted the 2-day event. They are the local leaders in managing the lower Snowy River Basin.

On 14 May, the committee kayaked along the estuary to Cabbage Tree Creek, observing the estuarine habitat and discussing its requirements.

The Snowy River has considerably less water than before because of river regulation. This prevents the river from moving sediment and sand. Occasionally the sand blocks the river mouth and impedes the river from flowing to the sea. This can occur when the river has low flows and the tides are high.

The blocked river mouth is detrimental for fish. They cannot swim in and out of the river to complete their lifecycles. The water level also rises and inundates the nearby areas, which causes vegetation dieback.

There are methods to open the mouth with machines, but this can cause more problems. It can drain the water that has oxygen and make the fish perish. The optimal way to keep the river mouth open is to use environmental water.

Meeting with the community

On 15 May, the committee had an open session with 25 community members from Marlo. They introduced the committee and its role. They also heard presentations from:

• the East Gippsland Catchment Management Authority on the water needs for the estuary
• the Arthur Rylah Institute on Australian grayling and eels
• the NSW Department of Climate Change, Energy, the Environment and Water on environmental water releases for the Snowy River.

The NSW Department of Climate Change, Energy, the Environment and Water explained the rules that limit the water deliveries and how they are reviewing them. They also shared the flow plans for 2024–25 and how to monitor and manage the safety of high releases and informed people how to register to get notifications of high releases.

The community members expressed their concerns about the impacts of the blocked river mouth.

A new trigger flow

Snowy Hydro, the NSW Department of Climate Change, Energy, the Environment and Water and the committee are pleased to announce the first trial of a 'trigger flow event' from Jindabyne Dam. This is a new way of releasing water that responds to natural cues in the weather and the nearby rivers. It is different from the current practice, where the flows are planned well in advance.

In May, there was rainfall in the Snowy catchment. This activated a pulse flow to mimic a natural event. The flow rose to a peak of 1,100 megalitres per day and then decreased over 2 days. This type of flow supports the ecological processes that depend on the weather.

The next trigger flow is planned for the Upper Murrumbidgee in June.

The Snowy Advisory Committee met via video conference on 13 December 2023 and 30 January 2024 to finalise environmental water plans for 2024–25. The committee was also updated on the Snowy Water Licence Review and the measures to improve the health of the Upper Murrumbidgee that were announced by the Australian Government.

2023 Snowy and montane highlights

The committee reflected on key challenges and outcomes for 2024, including the Snowy Water Licence Review, monitoring programs and environmental water management opportunities.

Snowy River flushing flow first

Flushing flows (>5,000 ML/day) provide multiple environmental benefits to improve the health of the Snowy River, including mobilising sediment, providing connectivity to wetlands and backwaters, and encouraging fish passage.

Due to Jindabyne Dam operational requirements and management, a flushing flow, where water is delivered over the spillway gates into the Snowy River, is not always achievable and usually not until spring in each water year.

High storage levels in Jindabyne Dam in early 2023 provided an opportunity to deliver a flushing flow in May instead of the usual spring timing. The committee was pleased to see the event occur, as healthy rivers require flow variability and delivering a flushing flow at various times of the year contributes to improving river health.

Snowy Water Licence Review update

As part of the Snowy Water Licence Review actions, the NSW Government investigated options to deliver environmental water to the Snowy River water via Mowamba Weir to increase the flexibility in flow delivery arrangements that help achieve environmental outcomes and be able to respond to natural cues such as rainfall events.

The committee has assisted the licence review process by providing advice on social and economic values. The department is considering the recommendations and next steps.

A webinar to update the community on the licence review was provided on 7 February 2024 and a recording is available.

Monitoring activities to inform future water management

The department has undertaken or commissioned several monitoring projects to inform the response to environmental flows and health of the Snowy and montane rivers. Monitoring has included frog and habitat assessments, fine sediment changes, water bug monitoring, environmental DNA sampling for fish and measuring water temperature and depth.

The monitoring data collected is critical for the committee to provide informed advice for managing environmental flows. The committee plans to hold a workshop in May 2024 to further discuss the monitoring program and outcomes.

Planning water for the environment releases for 2024–25

A moderate allocation of 204,963 megalitres (ML) of water for the environment is available for the Snowy River and a volume equivalent to 87,090 ML for the montane rivers. The committee discussed environmental water management in 2024–25, incorporating the best available science and expert knowledge.

In previous years, the timing of environmental releases has been scheduled for the water year, and there has been limited opportunity to adaptively manage flows in response to natural cues and other environmental needs. The committee was delighted to hear that the department is working with Snowy Hydro to incorporate changes to the timing of flow releases through the year for the Snowy and upper Murrumbidgee rivers for 2024–25.

Snowy River

The planned variable flow releases from Jindabyne Dam are designed to replicate a snow-melt river. The daily flow pattern incorporates a series of high flows and five 8-hour peaks, including a flushing flow. These flows aim to improve river channel health by mobilising sediment, encouraging productivity, and connecting wetlands and backwaters to the river that support water-dependent plants and animals such as frogs and water bugs, supporting native fish movement, including flows for Australian grayling, and supporting estuary health.

Adaptive management of flows is commonly used in environmental water management across the Murray Darling Basin and trials are planned for the Snowy River this year. The trial proposals include:

• Trigger flows – respond to natural flow cues based on real-time Thredbo River flow triggers resulting from rainfall events. If triggered, the highest planned release for the month <1,500 ML) will occur in the Snowy River around one day after the Thredbo flow trigger. This will be undertaken on up to 4 occasions throughout the water year.
• Estuary flows – trial and monitor a series of low flow variations to support estuary health and help keep the estuary open during summer and autumn 2025. The department has been working with East Gippsland Catchment Management Authority and Snowy Hydro to design the daily flows and allow some flexibility to increase flow rates in 2025 if conditions are dry. If required, the water would be moved from a higher flow period to achieve this.

When connected to the sea, the Snowy River estuary supports critical habitat for native fish migration and breeding including for the Australian grayling, which is nationally listed as vulnerable.

Montane streams

A total of 139.007 gigawatt hours of foregone Snowy Hydro electricity generation is available for 2024–25. The pre-determined gigawatt hour conversion rate to ML varies for the different montane reaches depending on the amount of foregone electricity that could be generated. For the targeted montane rivers in the upcoming water year this equates to 87,090 ML.

There will be sufficient environmental water to provide flows in the upper Murrumbidgee, upper Snowy River, Goodradigbee River and the Geehi River. Flows to these rivers will provide essential habitat for water-dependent animals, including water bugs, frogs, native fish and platypus.

The committee supported the proposal to allocate less water to the Goodradigbee River in 2024–25 to allow greater flows in the upper Murrumbidgee River, which supports the endangered Macquarie perch.

Upper Murrumbidgee River

The planned environmental releases will provide some natural flow seasonality and flow variability. This includes increased flows and peaks during October and December 2024 to support Macquarie perch movement between breeding sites.

There will be several short cease-to-flow periods with no flows delivered from Tantangara Dam from January to April 2025. Small pulses will be delivered during this time to allow limited fish movement and recharge the pools.

Similar to the flow trials for the Snowy River outlined above, the department is working with Snowy Hydro to implement flexibility by delivering 2 trigger flows for the upper Murrumbidgee. In June 2024 and April 2025, it is proposed to deliver a moderate peak (less than 500 ML/day) each month in sync with a rainfall event. The timing of the peak's delivery would be triggered by an increase in the hourly flow at the Murrumbidgee at the upstream Tantangara gauge.

These trigger flows aim to support natural cues, including productivity and Macquarie perch movement.

Next committee meeting

The next committee meeting will take place in May. A community meeting is planned as part of this, where the water release plan for the coming year and the outcomes of monitoring and investigations are presented to the public.

The Snowy Advisory Committee met via video conference on 23 October 2023 to endorse the committee’s strategic plan and receive updates on several initiatives. The committee also reviewed environmental water delivery to date for 2023–24.

Strategic plan

The committee adopted its strategic plan, providing a guiding framework for its activities and priorities. A key priority of the plan is to incorporate First Nations values and knowledge when providing advice on environmental flows for the Snowy and montane rivers. The plan is a living document and will evolve as set priorities are achieved, partnerships are developed, and new learnings are incorporated.

Snowy and montane flow update

Snowy Hydro provided an update on the environmental flows for 2023–24. The planned releases are tracking well.

All the high flows have been successfully delivered via Jindabyne Dam to the Snowy River. There is one remaining high 8-hour peak planned for 10 November 2023.

Due to high forecast rainfall, the high flow planned for 6 October 2023 was postponed by a week to prevent potential risks of downstream flooding. The Department of Climate Change, Energy, the Environment and Water thanked Snowy Hydro for accommodating the changes at short notice.

The successful delivery of 3 high flows has been achieved from Tantangara Dam into the upper Murrumbidgee River.

Upper Murrumbidgee Aboriginal Waterways Assessment video

The department presented a draft video on the Ngunnawal’s Aboriginal Waterways Assessment program in the upper Murrumbidgee River. The Ngunnawal community and the department have partnered to produce the video, highlighting the Ngunnawal's work assessing and documenting the river's cultural, social and environmental values. The video was produced in line with the priority goals of the committee’s strategic plan.

Flow recommendations for the Snowy estuary

Kerry Spencer (East Gippsland Catchment Management Authority) presented the findings from 2 commissioned projects: the Snowy River Flows Study (Victorian Reaches) and the Estuarine Flow Study.

The studies provide flow recommendations to support healthy ecosystems and habitats in the Snowy River from the Victorian border to the sea.

Recommendations included:

• Maintain baseflows in the Snowy River from January to April each year to prevent closure of the estuary entrance.
• Provide a large flushing flow every 2 to 3 years to scour out the entrance.
• Provide interannual flow variability to support different fish species.

Monitoring of the Snowy and montane rivers

The department updated the committee on the monitoring program for the Snowy and montane rivers. Staff will be busy undertaking and commissioning multiple monitoring activities over the coming months to help increase the committee’s and decision-makers’ knowledge to design daily flow patterns to improve ecological outcomes for the Snowy and montane rivers.

Macquarie perch

Macquarie perch larval surveys are planned for November to be timed with the suspected breeding period for the fish species in the upper Murrumbidgee River. Information will be collected on the timing of spawning for Macquarie Perch. Otoliths (part of the fish’s inner ear) will be examined to assess the age and growth rates of the species. The data collected from this monitoring will help to inform the timing of flows and the current health of the Macquarie perch population in the upper Murrumbidgee River.

Frogs

Staff will undertake the third year of frog monitoring in the Snowy and montane rivers. Frogs are sensitive to changes in flows and their environment. They can be used as an indicator of the health of a river system and connected wetlands. Monitoring will include identifying species and looking for evidence of breeding.

Mobilising sediment in the upper Murrumbidgee

A trial assessed whether high releases from Tantangara Dam mobilise fine sediment from the upper Murrumbidgee riverbed. The project was designed to get a quick snapshot of sediment movement. The results indicated that some sediment mobilised, and a more rigorous survey is recommended. Many water-dependant animals such as Macquarie perch require clean rocks to deposit their eggs.

Using eDNA to look at fish diversity

Dianne Gleeson (University of Canberra) updated the committee on a recent study using environmental DNA (eDNA) monitoring to examine fish diversity in the Snowy, upper Murrumbidgee and Goodradigbee rivers. Water samples were collected from 19 sites and the eDNA was examined in a laboratory to identify the fish species. The results included:

• detection of 7 fish species
• the upper Murrumbidgee recording the highest number of fish species (compared to the other rivers)
• a greater abundance of rainbow trout in the upper Murrumbidgee than in the Snowy River
• the highest abundance of brown trout in the Snowy River (compared to other rivers)
• only introduced fish species detected in the Goodradigbee River.

Other monitoring

The committee was updated on other monitoring undertaken or commissioned by the department. The monitoring included:

• genetic testing of platypus
• surveying the platypus population in the Snowy River below Dalgety
• water bug sampling in the Snowy, Geehi, Mowamba and Thredbo rivers.

The committee will hold a workshop with the department in early 2024 to take a closer look at the monitoring program and learn about the results of the planned activities.

Returning flows to the Mowamba River and providing more flexible flows in the Snowy River

The department updated the committee on Snowy Water Licence review actions investigating the return of flows to the Mowamba River below the weir and greater flexibility of environmental water releases from Jindabyne Dam into the Snowy River.

Work on the Mowamba Weir feasibility study will continue into the next phase to further investigate issues identified. This will include installation of a gauge to measure Mowamba River flows, the development of an agreed process to reduce Jindabyne Dam releases to offset the water delivered via the Mowamba River, and minimising foregone generation from the mini hydro generator on Jindabyne Dam.

The committee was pleased that some flexibility to change pre-planned releases in the Snowy River will be trialled during the 2024–25 water year. The trial release will respond to natural flow cues and will be based on real-time Thredbo flow triggers resulting from rainfall events. If triggered, releases will occur in the Snowy River around one day after the Thredbo flow trigger and undertaken on up to 4 occasions throughout the water year. These trial releases will be limited in size to avoid undesirable effects.

Additional information about the program

For further information about the environmental watering program, take a look at the:

• 2022-23 outcomes report.

The Snowy Advisory Committee met via video conference on 31 July to discuss the Committee’s strategic plan, hear about current monitoring programs and review progress on investigations about returning flows to the lower Mowamba River. 

Strategic Plan

The Committee discussed its draft strategic plan and resolved to finalise the plan at the next meeting following consultation. The draft plan sets a focus on incorporating First Nations’ values and increasing the participation of partners and stakeholders to improve outcomes for the Snowy and montane rivers. These measures will enhance the Committee’s capacity to advise decision makers that govern the use of water in the Snowy and Montane rivers. The draft plan reiterates the recommendations of the Committee to allow more flexible releases from Jindabyne Dam to improve the ‘naturalness’ of the river system and to remove Mowamba Weir to create an uninterrupted natural flow from the snow to the sea.

Monitoring of the Snowy and montane rivers

Platypuses

Dr Gilad Bino (University of NSW) presented the findings from a study of platypus populations in the Snowy River between Jindabyne and Dalgety. Dr Gilad found that the Snowy River supports a healthy adult platypus population; however, the proportion of juveniles is lower than found in comparable populations in the Eucumbene and Thredbo rivers. The NSW Department of Climate Change, Energy, the Environment and Water (NSW DCCEEW) is working with the Dr Gilad on potential options to investigate this further, including genetic analysis and monitoring using radio-tags.

Other monitoring

The Committee was updated on other monitoring being undertaken or commissioned by NSW DCCEEW. The monitoring included:

• environmental DNA sampling for fish in the Snowy, Mowamba, Goodradigbee and upper Murrumbidgee rivers
• water bug monitoring in the Snowy, Geehi, Mowamba and Thredbo rivers
• installation of further water temperature loggers in the upper Murrumbidgee to improve our understanding of the spawning triggers of the endangered Macquarie perch in the river
• installation of depth gauges at 2 new Snowy River sites.

The Committee was pleased to see the continuing increase in monitoring being undertaken in the Snowy and montane rivers and noted that further monitoring, including sedimentation and Macquarie perch larvae research in the upper Murrumbidgee, is being proposed should funding be secured.

Returning flows to the Mowamba River

NSW DCCEEW updated the Committee of the Mowamba Weir feasibility assessment – returning flows to the Mowamba River below the Mowamba Weir. Currently, flows from the Mowamba River (which would naturally flow into the Snowy River) are diverted via an aqueduct to Jindabyne Dam. Those volumes are then released as Snowy River Increased Flows from the dam. An action of the Snowy Water Licence Review requires the investigation of how Mowamba River flows may be allowed to pass the weir as a way of delivering water to the Snowy River. The assessment concluded it would be feasible in the short term to return flows by closing the aqueduct and allowing the Mowamba River’s flows to overtop the weir.

To progress this, several issues would first need to be progressed, such as the installation of a gauge to measure Mowamba River flows, the development of an agreed process to reduce Jindabyne Dam releases to offset the water delivered via the Mowamba and the development of a method to reduce foregone generation from the mini hydro generator on Jindabyne Dam. The Committee welcomed progress on this matter, noting both the Committee and a panel of independent scientists have previously recommended the return of flows to the Mowamba River.  The assessment was funded by NSW DCCEEW and conducted by Alluvium consultants.

Additional resources to support the Snowy and Montane rivers

The Committee welcomed news that the NSW DCCEEW has secured temporary funding to support an additional position, a Senior Environmental Water Management Officer. The role will provide additional support to the Committee, oversee monitoring programs and flow management planning, provide technical input to the review process of the Snowy Water Licence and engage with community and First Nations.

The Snowy Advisory Committee met in Queanbeyan on 31 January to finalise environmental water planning for 2023–24. During the meeting, the committee also received advice on the protection of environmental flows in the upper Murrumbidgee, heard a presentation on how flows are improving the Snowy River channel and discussed cultural water studies being undertaken on the upper Murrumbidgee River. On 1 February the committee attended a field inspection of the upper Murrumbidgee River, near Cooma, hosted by the Australian River Restoration Centre. 

Planning environmental water releases for 2023–24

The committee discussed how to use environmental water in 2023–24.

Snowy River

The committee uses available science and knowledge to inform its advice on the use of environmental water for the Snowy River. A 'natural flow-scaling' approach is applied as the basis for designing daily flow patterns. As Thredbo River flow volumes are similar to those of the modified Snowy River, historic flow data from the Thredbo River is used as a reference for daily and seasonal flows in the Snowy River below Jindabyne.

The 2023–24 water allocations may provide an opportunity to deliver an 8-hour flushing flow to the Snowy River. The delivery of a flushing flow of greater than 5,000 ML/day from Jindabyne Dam requires high dam levels and under some circumstances these dam levels can increase the risk of spills. The committee discussed options for the delivery of flushing flows that would minimise any such risk. Planned flow releases are expected to mobilise and flush sediments along and to the sides of the river channel, improving the health and condition of the riverbed and providing suitable habitat that will benefit macroinvertebrates.

Several planned releases of greater than 1,500 ML/day in spring and early summer will fill some of the connected ponds (wetlands), encouraging water plants to grow and providing important habitats for frogs and other aquatic animal to breed and feed. Small pulses in autumn are expected to provide improved habitat and food for platypus and other animals in this lean time of year, provide cues for the movement of native fish and assist in maintaining an opening at the Snowy River mouth.

Montane streams

There will be adequate environmental water in 2023–24 to provide flows in the upper Murrumbidgee, upper Snowy River, Goodradigbee River and the Geehi River. Flows to these streams will provide essential habitat for water-dependent animals, including water bugs, frogs, native fish and platypus. The committee supported the proposal to allocate less water to the Goodradigbee River in 2023–24 to allow greater flow in the upper Murrumbidgee River, which supports the endangered Macquarie perch. 

Upper Murrumbidgee River

The committee's advice for the upper Murrumbidgee for 2023–24 is to apply a modified natural scaling approach and to 'keep it (the river) clean'. This includes 3 high flows at or near 1,500 ML/day timed to flush gravels and cobbles prior to the Macquarie perch breeding season, providing better substrate for the fish to lay their eggs. There will be several short cease-to-flow periods which will result in 94 days (collectively) of no flows delivered from Tantangara Dam.

Protection of releases in the upper Murrumbidgee River

The Department of Climate Change, Energy, the Environment and Water informed the committee of measures being put in place to protect environmental releases in the upper Murrumbidgee from extraction. These measures include temporary water restrictions in the short term, with the department looking into options for permanent measures in the future. The protection of flows in the Upper Murrumbidgee River helps ensure their effectiveness and the committee applauds the department for progressing this work. 

Monitoring of the Snowy River Channel

Dr Teresa Rose presented the findings from a long-term study of the Snowy River channel's geomorphology. Dr Rose found that the Snowy River channel in the Jindabyne Gorge and the Dalgety Uplands has deepened, widened and increased in conveyance capacity since environmental flows began in 2002, with the greatest change occurring in the first decade (2002–2012) of the study.

Aboriginal waterways assessments

The committee heard from Ngunnawal Elder Mr Bradley Bell and others about the Aboriginal Waterways Assessments and cultural water studies on the upper Murrumbidgee River. The committee discussed options for producing a short video to highlight this important work.

Field inspection of the upper Murrumbidgee River

On 1 February the Australia River Restoration Centre hosted a field inspection of sites on the upper Murrumbidgee River near Cooma. The committee were briefed on Macquarie perch research by Associate Professor Mark Lintermans (University of Canberra) and catchment restoration work by the Rivers of Carbon project, the Upper Murrumbidgee Demonstration Reach and South East Local Land Services in cooperation with local landholders.

The Snowy Advisory Committee met via video conference on 19 December to review environmental water delivery so far for 2022–23, hear about current monitoring and research programs, and discuss planning for the 2023–24 water year.

The 2022–23 Snowy and montane rivers environmental watering program

Snowy River 

Snowy Hydro Limited (SHL) has reported 2022–23 as the wettest year since 1974. The record rainfall resulted in high dam levels and in spills, requiring SHL to make pre-releases (controlled spills) to lower dam levels from 4 October through to 1 December and again from 17 December. Consequently, environmental water releases from Jindabyne Dam into the Snowy River have been suspended for several periods in 2022. On 9 December a planned high flow environmental release was reduced significantly due to concerns about continuing high tributary flows and impacts to downstream third parties.

The committee expressed concerns about observed high levels of sediment deposited along the river from major tributary events that have occurred this year.

Upper Murrumbidgee River 

Concerns about high tributary flows also caused the cancellation of a planned high flow release into the upper Murrumbidgee River from Tantangara Dam, planned for 11 October 2022. The flows that were planned for this date have been redistributed.

There is insufficient environmental water available for the Upper Murrumbidgee to maintain daily releases for the entire 2022–23 water year, which will result in 95 days of no environmental releases for the remainder of the water year (20 December 2022 to 30 April 2023). Small flow pulses every one to 3 weeks will be provided to the river to help replenish pools and encourage a boost of food production for native water-dependent animals.

Montane streams 

The intake from Burrungubugge and Gungarlin rivers is currently out of operation. The resulting undiverted waters from those rivers are providing higher than normal flows to the Snowy River reach below Island Bend. Smaller releases usually made from Tolbar Creek Weir have been suspended during this outage and are being accounted as delivered as part of the higher flows from the Burrungubugge and Gungarlin rivers.

Monitoring environmental flows in 2022–23 

Frogs are sensitive to changes in flooding and flow regimes. In the Murray–Darling Basin floodplain river systems and associated wetlands, frog species respond strongly to environmental releases with large increases in breeding activity. Environmental water managers use the information collected to make informed decisions for environmental flow releases to benefit frog species by providing suitable habitat for recruitment and successful breeding opportunities.

The Department of Climate Change, Energy, the Environment and Water surveyed 13 sites in the Snowy and Upper Murrumbidgee rivers in December 2022, with 7 frog taxa recorded, including the alpine tree frog, listed as endangered in New South Wales. Preliminary results suggest that the ponds and wetlands connected to the rivers are playing an important role in providing critical habitat for several frog species, with evidence of successful breeding. Large numbers of native eels were also observed in the Snowy River below Jindabyne and platypus were also observed in both the Snowy and upper Murrumbidgee.

Planning environmental water releases for 2023–24 

The committee discussed preliminary plans for use of environmental water in 2023–24. Although the environmental water allocation will not be determined until February 2023, based on the current Murray–Darling Basin storages, it is anticipated to be a wet scenario. The committee will discuss 2023–24 planning further at the next scheduled meeting. 

Contacting the SAC

If you have questions or would like to express your views and values on the Snowy and montane environmental flows program, we would like to hear from you. Please contact the committee via sac@dpie.nsw.gov.au 

The committee next plans to meet in late January or early February 2023. 

The Snowy Advisory Committee met via video conference to review environmental water delivery so far for 2022–23, learn about planned monitoring and receive a presentation about the Snowy Flows and Snowy Estuary Flows projects.

The 2022–23 Snowy and montane rivers environmental watering program

Snowy River 

Environmental water releases are tracking well so far this water year (1 May 2022 to 30 April 2023) for the Snowy River. Approximately 52,600 megalitres (ML) has been released from Jindabyne since 1 May, including 2 of 5 planned 8-hour peaks. The purposes of the 8-hour peaks are to flush fine sediment and clean riffles and cobbles that provide important breeding habitat for water-dependent species, including macroinvertebrates, frogs and native fish. Many of the animals that use these habitats require clean rocks to live and successfully breed. The 8-hour peaks provide an important function to help make the Snowy River a healthy system. The highest planned 8-hour peak for this water year is for 5,000 ML, scheduled for 10 October 2022.  

Jindabyne Dam is currently 77% full with approximately 91,000 ML of airspace (as of 01/09/22). La Nina conditions have been forecast to continue, meaning that spring 2022 could be wetter than average. Snowy Hydro Limited will continue to monitor the dam levels closely and may need to consider pre-releases (controlled spill) from Jindabyne Dam if conditions remain wet.   

Upper Murrumbidgee River 

Releases from Tantangara Dam into the upper Murrumbidgee are on track, with approximately 18,500 ML of water for the environment delivered up to 1 September 2022. Three peak flows of 1,000 ML per day or greater have been incorporated into this year’s planned releases to help mobilise fine sediment and to provide suitable habitat for native fish and frogs. The final and largest peak of 1,500 ML is due to be delivered from midday for 24 hours on 11 October 2022.

Montane streams 

The environmental releases are being made from 6 locations in the montane streams for the Snowy River above Jindabyne Dam, the Goodradigbee River and the Geehi River. The daily environmental releases are on track for 2022–23. 

2022–23 planned monitoring 

DCCEEW re-established a targeted monitoring program for the Snowy and snowy montane rivers in 2021–22. Monitoring environmental flows provides information about current conditions and watering needs for the Snowy and snowy montane rivers to help DCCEEW and the committee to make informed decisions and recommendations for the future use of environmental water.  

Monitoring during 2022–23 includes macroinvertebrate surveys, frog surveys, water quality and geomorphology (river channel condition) studies. DCCEEW will seek opportunities for funding and to develop partnerships with other agencies and researchers to undertake additional monitoring.

Snowy River Flows and Estuary Flows projects  

Sean Phillipson, project officer with the East Gippsland Catchment Management Authority (EG CMA), provided the committee with an update on the Snowy Flows and Estuary Flow projects. EG CMA has funded the studies, which aim to have an integrated approach to develop flow recommendations for the Victorian reaches of the Snowy River and the estuary. The Flow Study is due to be completed by December 2022 and the Estuary Study in 2023.  

Snowy Advisory Committee Strategic Planning Workshop #2

On 1 September consultant Richard Baker held a second workshop with the committee.  The focus was on the incorporation of First Nations values of the Snowy River and montane rivers and to finalise the development of the Strategic Plan. The plan will include the committee’s vision for the Snowy and montane environmental watering program and help guide future decision making, including identifying short and long term goals. 

The committee plans to meet in November 2022 to commence planning for the 2023–24 water year. 

The Snowy Advisory Committee met in Cooma for the first time in more than 2 years. The committee reflected on the 2021–22 water year, reviewed environmental water delivery so far for 202223 and received multiple presentations on externally funded projects being implemented to support the program.

The 2021–22 Snowy and montane rivers environmental watering program

Snowy River

Continuing wet conditions, including the wettest December on record, saw Jindabyne Dam close to spilling in mid-December 2021. For the first time, the planned Snowy Rivers Increased Flows (SRIF) releases were changed by bringing 10 GL forward from the remainder of the water year for delivery in December. These changes to the release pattern aimed to mitigate the risks of an uncontrolled spill while also providing an opportunity to deliver environmental water in time with natural cues, reflecting the wet conditions.

The Jindabyne catchment continued to receive high rainfall, and the dam spilt on 19/20 December 2021, followed by a number of pre-releases (controlled spills) for the remainder of the 2021–22 water year to help reduce the risk of further uncontrolled spills.

Approximately 294 GL was released from Jindabyne Dam into the Snowy River, including 209 GL of Snowy Rivers Increased Flows and 85 GL of spill/pre-releases. Included in the spill volume was 18.7GL of Snowy Rivers Increased Flows 'borrow' that has been agreed to be repaid in 2022–23.

Upper Murrumbidgee River

Releases from Tantangara Dam into the upper Murrumbidgee remained on track for the water year, delivering 31.8 GL of water for the environment. The released flow included three peaks of at least 1GL/day to help mobilise fine sediment and provide suitable habitat for native fish and frogs.

Montane streams

Daily environmental releases to the targeted montane streams for 2021–22 included the Snowy River above Jindabyne Dam, the Goodradigbee River and the Geehi River. Releases remained within target.

2021–22 monitoring

The monitoring program now includes frogs, water temperature, water quality and surveillance cameras, and macroinvertebrates. The Department of Climate Change, Energy, the Environment and Water and NSW National Parks and Wildlife Service assisted with monitoring activities, allowing the expansion of the program.

Secured funding provided opportunities to further support the monitoring program. This included geomorphology surveys in the Snowy River and habitat assessments in the upper Murrumbidgee.

The information and data collected through the monitoring projects will help the committee to provide future advice on the planned releases for the Snowy and montane rivers.

Snowy River geomorphic study

Teresa Rose from River Rose Consulting presented the latest results from a geomorphic study looking at changes to the riverbed formation. The project is repeating a previous study undertaken in 2012 from below Jindabyne Dam to the Dalgety uplands.

The results indicate that the Snowy River channel is deepening over time, while the rate of channel widening is variable across sites. The results are promising and indicate that environmental flows support the long-term objective of having a smaller but healthy Snowy River.

Snowy River geomorphic study

Duanne White from the University of Canberra presented the upper Murrumbidgee 'habitat and barrier mapping project' results to the committee. The project identifies large barriers impacting Macquarie perch movement in key breeding areas located from Tantangara to the Numeralla River junction. Lidar, aerial imagery, on-ground surveys and community consultation are being incorporated to assist in the identification of important barriers.

The next stage of the project is to observe the barriers during environmental releases to see what role environmental water can play to drown out the barriers to allow for fish passage.

Environmental water releases for the 2022–23

The new water year commenced on 1 May. So far, environmental water releases are tracking well for the Snowy River, montane streams and the upper Murrumbidgee.

Jindabyne Dam remains close to full, and Snowy Hydro will consider conducting pre-releases to reduce the risks of an uncontrolled spill. The Department of Climate Change, Energy, the Environment and Water and the committee plan to provide input into the design of any pre-releases to maximise the ecological benefits.

Field to Tantangara Dam

The committee visited Tantangara Dam to get a first-hand look at how the dam operates, including the limitations for flow delivery into the upper Murrumbidgee. The committee was also provided with an update on the Snowy 2.0 project.

Snowy Advisory Committee Strategic Planning Workshop

Consultant Richard Baker held a workshop with the committee on 26 May. The workshop aimed to identify the values of the Snowy River and montane rivers to inform the development of the Strategic Plan. The plan will include the committee's vision for the Snowy and montane environmental watering program and help guide future decision making.

The committee next plans to meet in August 2022.

The Snowy Advisory Committee met via video conference on 9 February to finalise environmental water planning for 2022–23, review environmental water delivery so far for 2021–22 and receive a presentation from Australian National University on the Snowy Water Inquiry Outcomes Implementation Deed (SWIOID).

The 2021–22 Snowy and montane rivers environmental watering program

Snowy River

It was a wet end to 2021, with the wettest November since 1992 and the wettest December on record. The committee, NSW Government and Snowy Hydro agreed to bring forward the delivery of 10,000 ML of environmental water to December 2021 in an attempt to mitigate the risk of a dam spill, while also achieving environmental outcomes for the Snowy River. However, with significant rainfall of 120 to 140 millimetres across the Jindabyne Dam catchment on 18–19 December, the dam spilt on 20 December. Several pre-releases (controlled spills) were made for the remainder of December to mid-January 2022 to reduce the risk of further spills and manage public safety. The accounting of the spill and pre-releases has resulted in an environmental water 'borrow' of 18,700 ML. This volume will have to be paid back from future water allocations for the Snowy River.

With the exception of the dam spill and pre-releases from Jindabyne Dam, environmental water releases have been on track.

Upper Murrumbidgee River

There is insufficient environmental water available for the upper Murrumbidgee to maintain daily releases for the entire 2021–22 water year, with releases ceasing on 20 January. A small flush is planned for April to promote productivity (food) for native water-dependent animals such as the Macquarie perch.

Montane streams

Daily environmental releases to the targeted montane streams are also tracking as planned, providing essential water to aquatic plants and the animals they support, including frogs and water bugs.

Planning environmental water releases for 2022–23

The committee discussed how to use environmental water in 2022–23. As allocations reflect the current wet conditions, the committee's advice is for a wet scenario.

Snowy River

The committee uses available science and knowledge to inform its advice on the use of environmental water for the Snowy River. A 'natural flow scaling' approach is applied as the basis for designing daily flow patterns. As Thredbo River flow volumes are similar to the modified Snowy River, historic flow data from the Thredbo is used as a reference for daily and seasonal flows in the Snowy River below Jindabyne.

The 2022–23 water allocations will provide an opportunity to deliver a flushing flow to the Snowy River for the second year in a row. The flushing flow combined with several other higher flow releases during spring is expected to mobilise and flush sediments along and to the sides of the river channel, improving the health and condition of the riverbed. The higher flows will also flush sediment from gravel and cobbles (riffles), benefiting macroinvertebrates by providing them with suitable habitat.

Several planned releases of greater than 1500 ML/day in spring and early summer will fill some of the connected ponds (wetlands), encouraging water plants to grow, providing important habitats for frogs and other aquatic animal to breed and feed.

Montane streams

There will be adequate environmental water in 2022–23 to maintain flows in all the montane streams where an environmental flow has been allocated. This includes the upper Murrumbidgee, upper Snowy River, Goodradigbee River, Middle Creek, Diggers Creek and the Geehi River. Flows to these streams will provide essential habitat for water-dependent animals, including water bugs, frogs, native fish and platypus. Maintaining flows also provides essential habitat for the stony creek frog that attach their eggs to in-stream substrates.

Upper Murrumbidgee River

The committee's advice for the upper Murrumbidgee for 2022–23 is to apply a modified natural scaling approach and to 'keep it (the river) clean'. This includes 3 high flows above 1000 ML/day timed to flush gravels and cobbles before the Macquarie perch breeding season to provide a better substrate for the eggs. Fourteen flows above 500 ML/day to help flush the river and clean cobbles, and 19 short cease-to-flow periods, which will result in 136 days of no flows.

Funded projects

The Department of Climate Change, Energy, the Environment and Water has several projects that will help to improve our understanding of the Snowy and montane rivers and ensure the committee provides informed advice.

A geomorphology study will be undertaken to assess the Snowy River channel and the changes that have occurred to the river since environmental water deliver began in 2002. This work will be completed by the end of this financial year. The findings will be provided as a report and a presentation at the next Snowy Advisory Committee meeting.

Upper Murrumbidgee and Mowamba Instream Barriers and Habitat Assessment has commenced. The project will identify potential barriers for native fish.

eDNA DCCEEW will contribute funding to this NSW-wide project to identify freshwater vertebrates. Survey locations will include the Snowy River.

Snowy Water Inquiry Outcomes Implementation Deed research paper

The Australian National University presented its findings on an independent review of the Snowy Water Inquiry Outcomes Implementation Deed. The findings included recommendations for a formal review and clarity of water allocations. You can read the report: Snowy River environmental flows post-2002: lessons to be learnt.

Go to report

The committee next plans to meet in May 2022.

The Snowy Advisory Committee met via video conference on 20 December to review environmental water delivery for 2021–22, hear about current monitoring and research programs, and discuss planning for the 2022–23 water year.

The 2021–22 Snowy and montane rivers environmental watering program

Snowy River

Environmental water releases from Jindabyne Dam into the Snowy River up to 20 December 2022 were scheduled daily. Jindabyne Dam reached full supply level in the early hours of the morning on 20 December, and water began to spill over the spillway gates and into the Snowy River for the first time since March 2012.

Rainfall of up to 120 millimetres in some locations of the dam catchment area over 18–19 December resulted in significant dam inflows. It was also the wettest November since 1992, and December is shaping up to be one of the wettest on record, meaning it is likely that further spills or pre-releases (controlled spills) will need to be made to reduce the risk of a significant spill and to manage public safety.

The last of the 5 planned 8-hour peak flows was successfully delivered to the Snowy River on 9 November 2022 to contribute to moving accumulated sediment to keep riffles (rocks and crevices) clean and provide important habitat for waterbugs, frogs and fish.

Upper Murrumbidgee River

Daily releases into the Upper Murrumbidgee River from Tantangara Dam commenced on 25 May 2021. Releases varied daily and included 3 larger peaks to clean riffles and promote productivity, providing essential food for water-dependent animals, including platypuses and the endangered Macquarie perch.

Releases from Tantangara into the Upper Murrumbidgee were temporarily stopped for up to 3 weeks during November to complete required dam safety work. The flows that were planned for this period have been redistributed, including providing a small flush to promote productivity and support native frog and fish populations.

There is insufficient environmental water available for the Upper Murrumbidgee to maintain daily releases for the entire 2021–22 water year, which will result in 71 days of no environmental releases from January to April 2022. Environmental flows of 30 to 250 megalitres a day will continue until 1 January 2023 to provide some variability in flow height for river health. A small fresh in January and another in April 2022 will be provided to the river to boost food production for native water-dependent animals.

Montane Streams

Daily environmental releases to the targeted montane streams are also tracking as planned, continuing to provide essential water to the water-dependent plants and animals they support, including frogs and waterbugs.

Monitoring environmental flows in 2021–22

Frogs are sensitive to changes in flooding and flow regimes. In the Murray–Darling Basin floodplain river systems and associated wetlands, frog species respond strongly to environmental releases with large increases in breeding activity. Environmental water managers use the information collected to make informed decisions for environmental flow releases to benefit frog species by providing suitable habitat for recruitment and successful breeding opportunities.

The Department of Climate Change, Energy, the Environment and Water is trialling frog monitoring in the Snowy and montane rivers to determine if frogs can be used as a useful indicator to inform the management of environmental water.

Eighteen sites in the Geehi, Middle Creek, Diggers Creek, Snowy and Upper Murrumbidgee rivers have been surveyed so far, with 8 species recorded, including the alpine tree frog, listed as endangered in New South Wales.

Preliminary results suggest that the ponds and wetlands connected to the rivers are playing an important role in providing important habitat for several frog species, with evidence of successful breeding. Once all surveys are complete, we will examine the data to determine if the trial will be continued.

The department has funded projects to identify barriers to fish in the Upper Murrumbidgee River and a study of the Snowy River channel condition to commence in early 2022.

Planning environmental water releases for the 2022–23

The committee discussed preliminary plans for the use of environmental water in 2022–23. Although the environmental water allocation will not be determined until February 2022, based on the current Murray–Darling Basin storages, it is anticipated to be a wet scenario. The committee will discuss the 2022–23 planning further at the next scheduled meeting.

Contacting the Snowy Advisory Committee

If you have questions or would like to express your views and values on the Snowy and montane environmental flows program, we would like to hear from you.

The committee next plans to meet in February 2022.

The Snowy Advisory Committee met via video conference on 5 November to examine environmental water delivery so far for 2021–22, hear about current monitoring and research programs, and receive an update on the Snowy Water Licence Review.

The 2020–21 Snowy and montane rivers environmental watering program

Snowy River

Daily environmental water releases from Jindabyne Dam into the Snowy River are tracking as scheduled. To date, 4 of the 5 planned 8-hour high flow events have been delivered including the flushing flow event. These releases have been planned to mirror those of a natural snowmelt river based on Thredbo River.

To commence the flushing flow event, it was necessary for Snowy Hydro to partly open the Jindabyne Dam spillway gates. The release had an equivalent peak flow of 10,362 megalitres a day for 8 hours. The flushing flow generated enough stream power to move sediment and vegetation to improve the health of the river channel. High releases are used to move accumulated sediment to keep riffles (rocks and crevices) clean and provide important habitat for waterbugs, frogs and fish.

The last high flow event is planned to occur on 9 November 2021.

Upper Murrumbidgee River

Daily releases into the upper Murrumbidgee River from Tantangara Dam commenced on 25 May 2021. Releases varied daily and included 3 larger peaks to clean riffles and promote productivity, providing essential food for water-dependent animals include platypuses and the endangered Macquarie perch.

For only the second time since the environmental watering program began, Tantangara dam was operated to maximum capacity, delivering a 1,500 megalitre flow. Higher releases play an important role in wetting benches, inundating lower-level ponds and drowning out natural barriers to allow for fish passage.

Releases from Tantangara into the upper Murrumbidgee will cease for up to 3 weeks during November to complete required dam safety work. The flows that were planned for this period have been redistributed including to provide a small flush after completion of the safety work and in autumn to promote productivity.

Montane streams

Daily environmental releases to the targeted montane streams are also tracking as planned providing essential water to the water-dependent plants and animals they support.

Monitoring environmental flows in 2021–22

COVID and travel restrictions have prevented and/or delayed most of the planned monitoring activities. The Department of Climate Change, Energy, the Environment and Water deployed several surveillance cameras along the upper Murrumbidgee and Snowy River to record changes in flow height in June 2021. The images from the cameras clearly recoded the higher peaks, rise, and fall of the water levels in the river.

DCCEEW is planning to conduct frog surveys during November and December 2021 in the montane, Snowy and upper Murrumbidgee rivers. Frogs are sensitive to their environment and can be used as key indicators to determine the current health of a river system.

The information and data collected from the monitoring will be useful to inform planning for use of environmental water in the future.

Guest presentations

There were 3 guest presentations to provide the committee with information regarding current projects occurring in the Snowy and upper Murrumbidgee rivers.

East Gippsland Catchment Management Authority presented the Snowy FLOWS project. The project will identify flow recommendations for the Victorian reach of the Snowy River to support plants and animals, including native fish resilience, migration and spawning. The project is due to be completed in early 2022.

South East Local Land Services provided an update on the Research Recovery Project for the endangered Macquarie Perch. This species, which was once very common, has undergone serious and widespread population decline. The upper Murrumbidgee River supports one of the few remaining populations. Genetic rescue operations (translocations) as part of the project will lead to increased genetic diversity in targeted Macquarie Perch populations to increase resilience and stability of their populations. Further information is needed regarding the natural barriers and how much flow is required to drown out the barriers to allow for fish passage.

The University of New South Wales presented on the platypuses of the Snowy River research project that is currently underway. Ten platypuses in the Snowy River have been tagged and their movements being monitored. The study will help to increase the understanding of flow requirements for the species.

Snowy Water Licence Review

The committee was provided with an update on the current Snowy Water Licence review process and the investigations that are underway. For further information, visit the Snowy Water Licence Review.

Contacting The SAC

If you have questions or would like to express your views and values on the Snowy and montane environmental flows program, we would like to hear from you. Please contact the Committee via sac@dpie.nsw.gov.au

The Snowy Advisory Committee met via video conference on 20 May to review the 2020–21 Snowy and montane rivers environmental watering year, look at the year ahead and received an update on the Snowy Water Licence Review.

The 2020–21 Snowy and montane rivers environmental watering program in review

In 2020–21 the water allocation available for the Snowy River and montane streams was one of the lowest since the environmental watering program began. This was due to low rainfall and storage dam inflows in the Murray Darling Basin during the previous year. In 2020–21, a total of 130 gigalitres (GL) of environmental water was delivered to the Snowy and montane streams. 

The total volume of environmental water delivered to the Snowy and montane streams in 2020–21

91.5 GL was allocated to the Snowy River below Jindabyne in 2020–21 and of this 91.2 GL was delivered, resulting in a minor under use. The 0.3 GL under use has been added to the planned Snowy River flows for 2021–22.

During 2020–21 releases into the Snowy River had daily flow variability, with higher daily flows during winter and spring. There was not sufficient environmental water available to provide a large flushing flow event to move large sediment. Four smaller 8-hour flow events of above 1 GL were delivered to improve the river channel condition by moving fine sediment. The flows were designed to maintain river health and promote productivity (food) for water-dependent plants and animals, including turtles, fish, frogs and platypus.

In the montane streams, a foregone electricity generation value of 58.7 gigawatt hours (GWh) (equivalent to 38.8 GL) was available in 2020–21. To maintain flows to all the targeted montane streams equates to an electricity value of 71 GWh, meaning there wasn’t sufficient water available to achieve this. An adjustment to flow was made at Middle Creek (a Geehi River tributary) to compensate for the lower total. The aqueduct intake was partly opened allowing a portion of the flows to be diverted for Snowy Hydro purposes and a portion of the water to flow over the weir throughout the year. This was the first time the weir and aqueduct have been operated to maintain some continuous flows in this way. Without this arrangement, the flow would have had to cease for 3 or more months to make up the compensating water volume. The committee commended the efforts of Snowy Hydro and DCCEEW to work together manage the releases in this manner to maintain supply to the water-dependent plants and animals that live in Middle Creek.

A total of 3.1 GL of environmental water was delivered to the Upper Murrumbidgee from Tantangara Dam. Flow rates to the Upper Murrumbidgee were varied during the winter and spring to better maintain river health and functions. A key objective was to promote instream productivity to provide food and important habitat for the Macquarie perch, a fish species listed as endangered both in New South Wales and nationally.

2021–22 planned environmental water releases for the Snowy and montane rivers

The 2021–22 water year commenced on 1 May. There is 209.8 GL of environmental water available for the Snowy River below Jindabyne and 88.8 GL (142.272 GWh electricity value) for the montane streams, which includes 31.6 GL for the Upper Murrumbidgee river from Tantangara.

There are planned environmental water releases to the Snowy River for every day of the year. The flows have daily variability with higher release rates planned to be typical of a local snowmelt river. With significantly higher allocations available this water year, there will be an opportunity to provide five 8-hour peak events, including a good chance of achieving a larger spring flushing flow to the Snowy River if sufficiently high enough storage targets are reached in Jindabyne Dam. Such high flow events are expected to clean riffles and to mobilise and flush sediment to improve the health of the river channel. The water releases are currently tracking as planned and as of 19 May 2021 an estimated 6.2 GL had been delivered.

Daily environmental releases to the targeted montane streams are also tracking as planned and flows from Tantangara Dam into the Upper Murrumbidgee commence on 25 May. Flows to these streams are providing essential habitat for water-dependent animals, including water bugs, frogs, native fish and platypus.

Monitoring environmental flows in 2021–22

DCCEEW is finalising a monitoring program for this water year. The targeted program will monitor selected parameters of the environmental flows, including water temperature in the Snowy and Upper Murrumbidgee rivers. Water temperature plays a critical role in maintaining healthy rivers and having optimal temperatures can provide natural cues for native fish to breed.

Snowy Water Licence Review

The Snowy Water Licence is reviewed on a statutory schedule to identify potential licence improvements. The most recent review proposed investigation into options to better manage environmental allocations and flows and for improvement to the current water release rules. The committee was provided with an update on the current Snowy Water Licence review process and the investigations that are underway to generate advice for DCCEEW to consider and provide to government.

The Snowy Advisory Committee met via video conference on 5 February 2021 to finalise the flow release options for the 2021–22 water year for the Snowy and montane rivers and discussed the Snowy Water Licence Review.

There are 209.5 gigalitres of water available for Snowy River flows from Jindabyne for 2021–22. With wetter conditions in the southern Murray-Darling Basin this water allocation is significantly higher than the 91.4 gigalitres that was available in the previous year.

The committee uses available science and knowledge to inform its advice on the use of environmental water for the Snowy River. A ‘natural flow scaling’ approach is applied where historic flow data in the Thredbo River is used as a reference for daily and seasonal flow variability in the Snowy River below Jindabyne, as Thredbo River flow volumes are of a similar size.

The 2021–22 water allocations will again provide an opportunity to deliver a flushing flow to the Snowy River. Combined with several other higher flow releases during the spring season period this is expected to mobilise and flush sediments along and to the sides of the river channel, improving the health and condition of the riverbed. These flows should help with recovery of the river following the extreme fires of 2019–20.

Higher-level, more energetic water flows clean and flush the spaces between gravel stones to improve productivity and habitat for aquatic animals, including water bugs, crustaceans, frogs, fish and platypus. A strong platypus population has been observed along the Snowy River below Jindabyne since environmental flows were introduced.

There will be adequate environmental water for 2021–22 to maintain flows in all the montane streams which have had environmental flow allocated, including the upper Murrumbidgee, upper Snowy River, Goodradigbee River, Middle Creek, Diggers Creek and the Geehi River. Flows to these streams will provide essential habitat for water-dependent animals, including water bugs, frogs, native fish, and platypus.

There is 31.6 gigalitres available for Tantangara Dam environmental water releases into the upper Murrumbidgee during 2021–22. This will provide some natural flow seasonality and daily flow variability. The upper Murrumbidgee supports the largest of only three remaining natural NSW populations of Macquarie perch, listed as endangered both in New South Wales and nationally. The higher flows are intended to improve the health of the river by cleaning sediment from riffles and to provide suitable habitat for Macquarie perch to lay their eggs.

The Snowy water licence outlines Snowy Hydro Limited’s obligations in relation to water in the Snowy Mountains Scheme, including releases of environmental water. The licence is regularly reviewed to identify potential licence improvements and the most recent review proposed options for investigation to better manage environmental flows and improve the current water release rules. The committee was provided with an update on the current licence review and investigations that are currently underway, including examining the benefits of releasing environmental water to the Snowy River via Mowamba River and water release rules for greater flexibility. The committee noted that consideration of Mowamba River flows in the review process is very important to both the river and its communities and having greater flexibility would be essential for improving river health.

The Snowy Advisory Committee met via video conference on 2 December 2020 to discuss the current Snowy and montane flow releases, and potential releases for the 2021–22 water year for the Snowy and montane rivers – including the upper Murrumbidgee river.

South East Local Land Services (SE LLS) provided an update on catchment management for the Snowy and upper Murrumbidgee rivers. The last major pest plant control for the Snowy River was in 2016–17. For some areas this was the fifth application, and the outcomes were very successful. Catchment Action NSW grants are currently being implemented by SE LLS using an expression of interest process. Landholders can apply for grants for fencing, revegetation and installation of off-stream water points to improve riparian management. SE LLS can provide technical advice and support to empower landholders and communities for improved land management.

Prolonged drought conditions resulted in the Snowy and montane 2020–21 environmental water allocations being some of the lowest since 2011. With the small volumes of water made available, the last of 4 peak flows for the Snowy River was delivered on 28 October 2020 from Jindabyne Dam. The higher energy flow peaks help to move sediment from water channels and to maintain water quality and improve river health. These flows are providing important habitat for native plants and animals that live in the Snowy River, including platypus, fish and water bugs.

This water year flow reductions are required in the montane system, as there is insufficient water available to maintain flows at all of the weirs for the entire water year. One of the actions undertaken to meet the required reductions was to temporarily decrease Middle Creek flows from September for several months. Full releases to Middle Creek will recommence in January 2021. Most of the targeted environmental flows have now been delivered. The flows are to provide essential habitat and food for water-dependent animals, including native fish, water bugs, frogs and platypus. The department will be undertaking macroinvertebrate surveys and trialling underwater video surveillance for fish species at Middle Creek, Diggers Creek, Geehi River and the upper Snowy River. A follow-up observation trip is planned for April 2021. The data collected from these surveys will help to inform the committee of the current health of these creeks and rivers.

With average rainfall and stronger inflows into the Murray–Darling Basin, the 2021–2022 outlook on water availability for the Snowy and montane rivers is looking much better.

A ‘natural flow scaling’ approach is used to deliver environmental water to the Snowy River below Jindabyne Dam. Thredbo River flows are a similar size to the volume of environmental water that is now available for the Snowy River below Jindabyne Dam, so the committee uses historic flow patterns in the Thredbo River as a reference to guide the decision-making process for water releases into the Snowy River. Using this approach and the best available science, the committee is working through the flow options for 2021–22 to prepare its advice to the NSW department.

The outlook indicates there will be sufficient water available to run water through all of the montane river assets, including Middle Creek and the Goodradigbee River. There will also be sufficient allocation to provide some environmental flow from Tantangara Dam into the upper Murrumbidgee River for water-dependent plants and animals and to improve river health above Cooma.