资源环境科技发展态势分析平台

Commonwealth Environmental Water Office
MEDIA RELEASE
24 September 2021

The wet conditions in the Murray valley have resulted in higher river flows for the first time in several years, benefiting both wetlands and rivers. The carbon-rich water flowing off the floodplains, also known as blackwater, is critical to wildlife in our rivers — it provides food for native fish, yabbies, shrimp and many other aquatic animals.

Interim Commonwealth Environmental Water Holder, Mr Hilton Taylor, said it is great to see the environment responding to these flows, with the flushing of the floodplain providing long term benefits. We are also watching water quality closely and are ready to respond early, as a precaution if conditions decline.

In the Edward/Kolety-Wakool rivers, water for the environment is being delivered in partnership with Murray Irrigation Limited (MIL) to create safe-zones of fresh water for native fish, crayfish, and other aquatic animals.

“Using MIL’s network of channels and escapes, small volumes of oxygenated water can be delivered to create areas of better quality water, as is currently happening at the Wakool escape. Native fish and crays can move to these areas and improve their chances of survival, should they need to” Mr Taylor said.

The approach has been designed with the Edward/Kolety-Wakool Environmental Water Reference Group and draws on lessons learned from previous low-oxygen events in 2016, 2012 and 2010.

The delivery of this water will be responsive to changes in conditions and advice from the SES and local communities.

“We are thankful for the local community representatives, and the broader community, for their efforts in responding to previous low-oxygen events in the Edward/Kolety-Wakool rivers. We couldn’t use water for the environment to help native fish in this area without their support”.

With the Commonwealth Environmental Water Holder using MIL infrastructure, and paying associated fees, the delivery of this water is achieving multiple benefits. Michael Pisasale, MIL water policy manager said that MIL was investigating other sites that could also be used to provide similar habitat, depending on local community support.

“MIL irrigation infrastructure can be used to help keep local waterways healthy. It is a win-win for irrigators, local communities and native fish!” he said.

Scientists from Charles Sturt University have water quality monitoring in place to capture data as water for the environment is delivered. Water managers will continue talking with local communities, including First Nations about the progress of the flow over the coming weeks.

This work is possible thanks to the collaboration and support of the local community and our water delivery partners - NSW Department of Planning, Industry and Environment, NSW DPI Fisheries, Charles Sturt University, WaterNSW, Murray Irrigation Ltd, and the Murray-Darling Basin Authority.

Fast facts

Deliveries of water for the environment began on 15 September 2021 at the Wakool escape, and planning is underway for other MIL irrigation escapes.

• Wakool escape – 200 megalitres/day – commenced

Flow rates will be adjusted depending on river flows and may be reduced as river flows peak.

The Edward/Kolety-Wakool Environmental Water Reference Group includes representatives from Wakool Rivers Association, Edward-Wakool Anglers Association, Western Murray Land Improvement Group and Murray Irrigation Limited.

Further updates will be provided throughout the flow and can be found at: Edward/Kolety-Wakool rivers - 2021 Flow update.

About blackwater

The wet conditions in the Murray valley have resulted in higher river flows, giving wetlands and floodplain forests a much-needed drink. These flows also flush leaf litter, grass and other plant matter from forests and farmlands into the river, resulting in ‘blackwater’. This organic matter is eaten by bacteria, which in turn become food for fish. This natural process is critical to the ‘food chain’ in the river.

However, without regular flooding, leaves and plant matter build up. If large amounts of organic matter enter the river, bacteria can multiply quickly (particularly in warmer temperatures) and consume the oxygen in the river. This causes ‘hypoxic conditions’, with the low oxygen levels having devastating impacts on native fish, crayfish, and other aquatic animals.

For more information on hypoxic blackwater see: NSW DPIE - Blackwater factsheet

Water for the environment in action in 2016 - the light brown oxygenated water (at the top of the image) was released from the MIL irrigation network creating safe zones for native fish escaping the hypoxic blackwater (bottom of the image). Photo: CEWO, 2016.