High water flows down the Murray in South Australia will persist over the next three months, although forecasts for peak river levels remain unchanged.
In its latest update on the flows through the SA Riverland, the state government says the peak is still expected to hit 135 gigalitres a day early next month.
It says levels above 100GL a day will be maintained through to the end of January, longer than originally thought.
There is a chance peak levels could exceed 150GL but only if there's more rain near the SA border.
Emergency Services Minister Joe Szakacs said while flood projections remain steady, residents in low-lying areas should continue to prepare.
"It's important that river communities remain vigilant, particularly those with low-lying shacks," he said on Thursday.
Water Minister Susan Close said the rising river levels were also expected to trigger a black water event with the large amounts of organic matter washed into the river system starving fish of oxygen.
"Fish and other aquatic animals may become stressed when oxygen levels drop below a certain level. Large-bodied native fish such as Murray Cod are particularly vulnerable," she said.
The Department for Environment and Water and SA Water are working with the Murray-Darling Basin Authority, fish scientists and upstream states to provide a haven of better-quality water for native fish in and around Lake Victoria in western NSW.
Flooding down the Murray is expected to result in some SA shacks, houses and community infrastructure being inundated.
It will also put stress on a system of levees with authorities most concerned for two at Renmark.
Remedial work has already begun to repair and reinforce those levees while a series of community meetings has also been held to provide information to local residents.