About Snowy River Increased Flows
The Snowy Water Inquiry Outcomes Implementation Deed (SWIOID) targets environmental flows of 212GL per year to be released into the Snowy River.
Read more about the legislative context and the background to the environmental reforms and water recovery achieved through the Snowy Water Initiative.
Environmental water priorities
The Snowy River Increased Flows (SRIF) program is managed by the NSW Department of Climate Change, Energy, the Environment and Water – Biodiversity, Conservation and Science (DCCEEW-BCS), in consultation with the Snowy Advisory Committee, NSW DCCEEW-Water and Snowy Hydro. NSW DCCEEW-BCS leads the team in determining annual environmental water priorities for the Snowy River and designing a flow regime with the available water to achieve these priorities.
You can find detailed information on the SRIF program, and the ‘Annual environmental water priorities in the Snowy and Snowy montane rivers’ on the NSW DCCEEW - BCS website.
Where sufficient water allows, the NSW, Victorian and Commonwealth governments have agreed that ecological objectives would be best achieved by releasing annual ‘flushing’ flows. These high flows improve river health and the physical condition of the in-stream habitat by scouring and transporting fine sediment.
It is expected that as the river physically responds over time to the higher flows, the focus of the recovery process will transition to meet other ecological objectives.
Releases into the Snowy River in the 2024–2025 water year
A total of 204,963 megalitres (ML) of environmental water will be released to the Snowy River below Jindabyne Dam during the 2024–25 water year, which includes
- 196,463 ML of SRIF and
- 8,500 ML base passing flow.
The flow regime includes eight separate ‘high-flow’ events between 27 June and 21 November 2024.The daily flow for each of these high-flow events will be near or above 2,500 megalitres per day (ML/d). High-flow events are generally released at midnight, with a constant flow rate for 24 hours. Five of the high flow release events will include a higher peak flow rate over 8 hours from 8am to 4pm.
A flushing flow is planned in October, which will be delivered if Jindabyne Dam water levels are high enough to enable delivery of flows via the spillway gates. If water levels are insufficient to achieve this, a peak flow as low as 5,000 ML/day will be released via the cone valves.
Frequent smaller flow releases, below 2,500 ML/d, will also be made throughout the year.
Read the overview of the plan for this year in the media release: Snowy River high-flows to commence in mid May
More detail is available in the Snowy River high-flows FAQs.
High-flow release schedule for 2024-2025
The table shows the schedule for high-flow releases. “High flow” releases are those in excess of 2,500 ML/day, which is the threshold above which flows may have the potential to create safety risks, based on local risk knowledge and experience from past releases.
| Date | Volume |
|---|---|
| Thursday 27 June 2024 | Daily flow of 2,977 megalitres per day (ML/d) over 24 hours, with equivalent peak flow 4,006 ML/d for eight hours. |
| Wednesday 21 August 2024 | Daily flow of 3,549 ML/d, with equivalent peak flow 4,916 ML/d for eight hours. |
| Wednesday 28 August 2024 | Daily peak flow of 4,935 ML/d over 24 hours. |
| Thursday 19 September 2024 | Daily peak flow of 3,135 ML/d over 24 hours. |
| Thursday 3 October 2024 | Daily flow of 3,917 ML/d, with equivalent peak flow of 4,787 ML/d for eight hours. |
| Monday 14 October 2024 | Daily peak flow of 2,923 ML/d over 24 hours. |
| Wednesday 23 October 2024 |
Daily flow of 5,596 ML/d over 24 hours with equivalent peak flow of 9,563 ML/d for eight hours (largest flow) if Jindabyne Dam levels are high enough to enable delivery.
If Jindabyne Dam levels are not high enough to enable delivery, the daily flow may be as low as 4,200 ML/d over 24 hours with equivalent peak as low as 5,000 ML/d for eight hours. |
| Thursday 24 October 2024 | Daily peak flow of 2,575 ML/d over 24 hours. If Jindabyne Dam levels are not high enough to enable the higher peak delivery on 23 October, the 24 October daily flow will be 3,525 ML/day over 24 hours. |
| Thursday 21 November 2024 | Daily flow of 2,410 ML/d over 24 hours, with equivalent peak flow 3,837 ML/d for eight hours. |
Note: Flows will commence at 00:00am (midnight) on the date listed for a period of 24 hours. Peak 8-hour flow releases will occur between 8am to 4pm local time.
Planned flows may be modified or cancelled subject to climatic, environmental or operational conditions near to the time of release. The department will endeavour to inform the public of changes to high-flow releases, where possible.
Whilst the volumes of smaller releases, less than 2,500 ML/d, are also planned at the start of the year, these may be changed at any time without notice. This allows greater flexibility in the delivery of environmental releases, which provides improved environmental outcomes.
Introduction of flexibility to the delivery of smaller releases
As an outcome of the Snowy Water Licence Review, flexible delivery of smaller flows may be introduced on a trial basis in 2024/25, whereby releases will be made in response to natural cues such as rainfall events. This will help support river health and water dependant plants and animals including native fish.
This adaptive management approach is commonly applied in other rivers’ environmental watering programs. This means that for releases under 2,500 ML/d, the volume and timing of planned releases may change without notice.
Flexible delivery will not apply to high-flow events (i.e. great than 2,500 ML/day) for the 2024/25 water year, although we may move towards greater flexibility of high-flow events in the future.
Design rationale for environmental releases
Flushing flows are important to help develop a more defined river channel within the former riverbed to assist in achieving the long-term goal of returning the Snowy River to a smaller, but healthy montane river.
High-flow water releases are designed to better mimic the natural flow characteristics that are seen in Snowy montane rivers, including snowmelt and ‘freshes’ that occurred before the construction of the Snowy scheme, with the aim of improving the long-term health of these river systems.
High flow releases are generally planned over winter and spring. This reflects the pre-regulation flow regime of a mixed rainfall and snowmelt river system characteristic of the Snowy Mountains.
There are generally periods of lower flow in summer and autumn, broken by pulses of higher flow which are aimed to help maintain the opening of the Snowy River estuary and support the seasonal movement of native fish.
A series of smaller flow pulses has been demonstrated to improve river health by establishing a new smaller channel, wetting the riparian zone and promoting the establishment of aquatic and riparian vegetation.
There is a high degree of daily flow variability with complex multi-peak hydrographs that are typical of rivers in the Snowy Mountains.
Safe management of high flows
The department works with Snowy Hydro and other relevant agencies to ensure the safe management of high flow releases. The Snowy River Increased Flows Safety Management Plan 2023-28 (PDF, 1440.67 KB) details the processes that are followed. This Plan is reviewed annually for currency.
The department will publish 'rising river alerts' below and issue them to relevant media organisations several days prior to each of the eight high-flow events.