Frequency, timing and duration of environmental water releases

The frequency of environmental water releases enabled by the Reconnecting River Country Program's Murrumbidgee Project (i.e., higher flows greater than 22,000 ML/d and up to 40,000 ML/d at Wagga Wagga gauge) will vary over time depending on water availability, climate and ecological conditions.

Over the long-term, it is anticipated environmental water releases above 32,000 ML/d and up to the new limit of 40,000 ML/d at Wagga Wagga will occur on average about three to five years per decade. Smaller releases, up to 32,000 ML/day at Wagga Wagga may be more frequent.

Environmental water releases will include some new events and some events extending the duration of existing unregulated events. They would not occur during extreme wet conditions when there is elevated flood risk.

Most of these environmental water releases will occur from August to October. Occasionally, when conditions are appropriate, releases may occur earlier in May to July, or extend into November.

Releases during summer months will be infrequent and mostly involve adding to an existing unregulated flow event to mitigate hypoxic blackwater risk.

The duration of these environmental water releases will generally be for three to five days at the peak flow rate and will be followed by a gradual reduction in flows back to background flow levels.

Further information on the proposed environmental water releases is available here:
Proposed environmental water releases in the Murrumbidgee.

Inflows from tributaries upstream of Wagga Wagga

Environmental water releases from Burrinjuck Dam will continue to consider inflows from the Tumut River (including Blowering Dam releases), together with inflows from unregulated tributaries such as Jugiong Creek and Tarcutta Creek, to ensure the flow limit at Wagga Wagga is not exceeded during environmental water releases.

Assumptions regarding Billabong Creek flows

Environmental water releases will contribute flows into Yanco Creek and subsequently into Billabong Creek via Colombo Creek. Environmental water releases reaching Billabong Creek through Colombo Creek will be small relative to flows coming from the Billabong Creek catchment upstream of Colombo Creek.

The Billabong Creek catchment upstream of Colombo Creek will remain the primary contributor of high flows in Billabong Creek. However, there is potential for environmental water releases to coincide with high flows coming from the Billabong Creek catchment.

The modelling allows for up to a 2,300 ML/d contribution from the unregulated Billabong Creek upstream of Colombo Creek (including via the Nowrannie Creek anabranch), which covers approximately 90% of flows during the period August to October when environmental water releases will typically occur.

This allows for environmental water releases under a variety of conditions while noting that managed environmental water releases will not occur during extreme wet conditions when there is elevated flood risk.

Estimated upper limit flow rates and gauge heights for a flow limit of selected_flow at Wagga Wagga gauge are shown in Table 1, below.

Table 1: Flow rates and gauge heights for a flow limit of selected_flow at Wagga Wagga gauge

Murrumbidgee River

Welcome to the Reconnecting River Country Program inundation interactive map. The map provides access to the program's modelled outputs showing potential inundation extents and depths for the flow limits considered by the program.

This app focuses on the Murrumbidgee River between Burrinjuck Dam and the River's confluence with the Murray River, including the Yanco-Billabong Creek system (the Murrumbidgee Project). The default flow option displayed in the app is 40,000 ML/d at the Wagga Wagga gauge.

What's new

The interactive map has been updated to simplify and improve the inundation information presented. The updates include:

Future model revisions

The NSW Department of Climate Change, Energy, the Environment and Water (DCCEEW) is continuing to improve the modelling and accuracy of the inundation mapping. Further refinements to the modelling and mapping will occur over time. Past revisions to the modelling are listed above and any future revisions will also be identified here.

Modelling report

Further information describing the modelling used to provide these inundation extents can be found in the Reconnecting River Country Program, Murrumbidgee Project, Hydraulic modelling summary report, which is available at the Reconnecting River Country Program Information hub.

Using the app

To show different flow options, choose one of the layers and it will show you on the map the changing inundation.

You can also zoom and pan around the map using your mouse and the included tools:

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Default view

Base Maps

Base map options can be toggled in the Layer Control and can be displayed below inundation extents:

Bridges

The mapping shows the extent of inundation, including the presence of water under road, highway and rail bridges. For bridges, the mapping does not accurately indicate inundation. The mapping product is overlain over aerial imagery which may appear to show bridges as being overtopped by water, but may represent water under the bridges.

More information

For more information on the program, please refer to the Reconnecting River Country Program Website on the DCCEEW website.

Disclaimer

© State of New South Wales through the Department of Climate Change, Energy, the Environment and Water (DCCEEW) 2025. The information contained in this publication is based on knowledge and understanding at the time of writing (Aug 2025). However, because of advances in knowledge, users are reminded of the need to ensure that the information upon which they rely is up to date and to check the currency of the information with the appropriate officer of the Department of Climate Change, Energy, the Environment and Water or the user’s independent adviser. For more information, please visit dcceew.nsw.gov.au/copyright