Eight levees have suffered major failures along the Murray in South Australia with serious defects identified in a further 53, as water continues to surge down the river ahead of peak flooding expected to begin later this month.

State Emergency Service Chief Officer Chris Beattie said most of the levees to suffer major issues had been constructed privately.

However, partnership he said some leaks had been spotted in a levee helping to protect the hospital at Renmark and work was underway to ensure more serious issues did not develop.

There were no concerns about the levee's overall integrity.

A levee at Ponde east of Adelaide also failed on Friday, isolating about six properties.

Ms Beattie said repairs were being made where possible and checks on all levees would continue.

"By and large we're very pleased with the way that patrolling and monitoring program is going and the responsiveness with getting contractors on site," he said.

In the latest series of warnings, watch and act messages are in place for low-lying areas at Tailem Bend and Murray Bridge where some residents could expect to be flooded or isolated.

About 4000 properties across the length of the Murray in SA are expected to be inundated with more than 1100 flooded so far.

The high-water mark is likely to hit Renmark, near the Victorian border around Boxing Day and then reach Murray Bridge by January 17.

Daily peak flows are still forecast between 190 and 220 gigalitres but then expected to drop back to about 150GL by February, allowing clean-up work to begin.

Premier Peter Malinauskas said while the flooding was devastating for property owners at risk, the environmental benefits were starting to be felt.

He said the Murray mouth was getting wider, bringing with it improved water quality for the region, including the Coorong.

"While there's a human tragedy here that we're very conscious of and that occupies our main focus, there's a massive environmental benefit that will occur as a result of this volume of water coming down the river," he told reporters on Monday.

Also on Monday, the government started rolling out business support grants with $600,000 approved so far for those companies forced to close.

The grants are part of a wider $51.6 million assistance package, including direct emergency payments to home owners.

The flood event will be the worst in SA since the Murray rose to record levels in 1956.

e-ISSN: 2317-8361 | DOI da revista: http://doi.org/10.12957/hne