Menindee Lakes community update

The fish deaths are believed to be attributed to hypoxic blackwater, a naturally occurring phenomenon which causes extremely low dissolved oxygen levels.

The scale of this event has been exacerbated by recent hot weather and significantly increased numbers of fish in the system as floodwaters recede.

NSW Department of Primary Industries – Fisheries (DPI Fisheries) has identified the dead species as predominantly bony herring, although other species have also been affected.

Similar fish death events have also occurred elsewhere in the state in the wake of last year's record flooding, most notably along the Murray River.

The fish deaths are a natural event associated with record flooding in the area. There are very limited management actions that could have been taken to prevent it from happening.

Nonetheless, WaterNSW has been working closely with other government agencies over the past few months to manage the risk of hypoxic (low oxygen) blackwater events – on the back of record flooding over the past 18 months.

The work is part of a multi-agency government initiative to monitor the impacts of regional flooding, which typically results in reduced oxygen levels as floodplain water, rich in organics, vegetation and debris, flows back into the river channel.

For WaterNSW, this has included increasing monitoring at Menindee Lakes in recent months to track water quality impacts resulting from prolonged flooding in the region.

In recent days WaterNSW has increased water quality testing in the Lower Darling, including downstream of Weir 32.

Water quality information is available to the public on WaterNSW’s Real Time Data website and provided to the Department of Planning and Environment – Water (DPE Water), DPI Fisheries and the Murray Darling Basin authority (MDBA) to help them with their work.

WaterNSW is also working to support DPE Water and environmental water holders by operating the lakes to ensure the best quality water from environmental water holder accounts is released downstream – helping to boost dissolved oxygen levels in this river reach.

An Emergency Operations Centre led by the NSW Police has been activated at Menindee to coordinate multi-agency operations in response to these fish deaths in the lower Darling-Baaka River.

A sub-working group, comprising DPI Fisheries, DPE Water and WaterNSW has been set up to investigate clean-up options and advise the Emergency Operations Centre.

WaterNSW is assisting DPI Fisheries who are the expert agency on fish deaths.

Essential Water has increased sampling and testing of drinking water to ensure it continues to meet the Australian Drinking Water Guidelines. They use laboratories certified to Australian standards and NSW Health reviews the results. They can confirm the quality had not been impacted by event and therefore safe for customers to drink.

• A community town hall meeting was held today (Tuesday 21 March 2023) in Menindee.
• The latest information from the Police Emergency Operations Centre can be found here.
• Observations of struggling fish or deaths can be reported directly to DPI Fisheries on 1800 043 536.
• The latest information on water quality can be on WaterNSW’s Real Time Data website, and algae alerts can be found on the WaterInsights portal.
• For more information about fish kills, as well as recent reports of observations and causes, please visit Fish kills in NSW.
• These types of events can be distressing to members of the community, and anyone who requires health, welfare or other support can contact local community support services. A comprehensive list of services can be located online here