Floods prompt rise in fish, birds, fuelling climate hopes for Coorong

Flooding of Australia’s Upper and Lower Murray River systems in 2022-23 saw the biggest flows in 50 years reach the Coorong, Lower Lakes and Murray River mouth and researchers say it’s already having an ecological impact.

The Coorong is a wetland of local, national and international importance and one of the most significant waterbird habitats in the Murray-Darling system.

But the health of the Coorong has declined along with river flows in the embattled Murray River, a situation that presents an ongoing threat to the Coorong’s value after it already sustained substantial damage during the Millennium Drought (1996-2010).

Of significance also are expected impacts from climate change, namely decreasing freshwater flows into the Coorong system, rising sea levels, and the warming of land and sea.

Such impacts will likely result in increased salinity, changes to fish and bird habitats, and sections of the Coorong possibly becoming disconnected because of declining freshwater inflows.

Various government and research plans have been put in place to stem the decline of the wetland, and other recent changes may also be of help, including restoring environmental flows to the Murray-Darling river system, and offering water buybacks from irrigators, reintroduced from March.

But perhaps it took Australia’s three wet La Niña years for scientists to be able to gather at the coastal town of Goolwa at the mouth of the Murray River, for a water forum of mainly good news: Ecological impacts of the recent floodwaters had been of benefit to the Coorong food web, with an increase in fish and waterbirds, particularly pelicans and swans.

As well—and also a result of the recent flood flows—South Australian River Murray water users have started the 2023-24 financial year with 100 per cent of their allocation, for the third successive year. 

Held in May, the gathering coincided with public consultation on a Draft Coorong Roadmap to restoration, which closed submissions mid-June with results yet to be published.

The May gathering in Goolwa was called the Healthy Coorong, Healthy Basin Science Forum, which saw some of Australia’s top scientists speak to their research that had underpinned the draft roadmap.

At the forum, Program Leader of The Living Murray Department for Environment and Water, Adrienne Rumbelow, presented observations from the 2022/23 River Murray flood.

Peak flows recorded in the upper Murray had been similar to those of 2016 and 1993, she said, causing Dartmouth dam to spill in October-November.

“Spring and summer [flows] … were well above long-term averages for this year; also last year we were just above long-term averages as well; that primed the system really nicely, so a lot of the storages were already full before we had all this extra water come down.

“Dartmouth dam filled, and it was the first time it has spilled since the 1990s … with 10 000 GL coming past Yarrawonga, so a huge amount of water.

“But it was very peaky … drying off since mid to late November … so it happened quite quickly through spring and then it was drying down again fairly quickly.”

The Healthy Coorong, Healthy Basin (HCHB) program aims to manage the Coorong for ecological health, helping the Coorong, Lakes Alexandrina and Albert Wetland Ramsar sites to maintain their significance.

The good research news is being helped further by the establishment of a new water research hub of the Goyder Institute for Water Research to be based in Goolwa, SA. The Institute is a collaborative partnership of the SA Government, CSIRO, Flinders University, the University of Adelaide and the University of South Australia.

In May, the Australian Department of Climate Change, Energy, the Environment and Water granted $8 million over 4 years from 2022-23 to the Institute to work with First Nations groups and local communities to investigate the impacts of climate change on the Coorong, Lower Lakes and Murray Mouth region.

The hub is an alliance of the SA Government, CSIRO, Flinders University, the University of Adelaide and the University of South Australia.

Through its research as part of the HCHB program, jointly funded by the Australian and South Australian governments, the Goyder Institute has released a suite of Climate Adaptation reports.

At the end of June, and led by Institute Interim Director Alec Rolston, the GIWR launched a three-year strategic plan focussing on water for people, the environemnt, industry, and climate adaptation.