The Murray River has breached a levee southeast of Adelaide with a number of homes at risk of flooding.
The State Emergency Services says water is flowing into an area behind the levee at Wellington impacting at least one street.
It says crews are working with council officials to support local residents.
The incident comes as river levels along the length of the Murray continue to drop with more restrictions being eased upstream and flooding falling to minor levels in some areas.
Along the lower Murray significant amount of water were still present, and levees remained under pressure, the SES said.
A watch and act warning remains in place for those areas.
"So there is still a threat to you and your family's safety," the SES said.
"Water safety risks continue with strong currents and debris in the water. You should monitor your situation and are urged to remain vigilant."
A similar watch and act warning remains in place for areas around Blanchetown and Overland Corner, northeast of Adelaide.
While from Overland Corner to the Victorian border, the threat levels are significantly reduced.
At the same time, authorities on Friday lifted some more restrictions on river activities with swimming, jet skis, boats and houseboats now allowed on some sections.
Those activities may still be subject to speed restrictions.
At the height of the flooding in SA about 4000 properties were impacted to some degree as Murray water levels rose to their highest for more than 50 years.
