The State Emergency Service said this afternoon there was a high risk of flooding for low-lying areas in Younghusband, Mannum, Caloote, Pompoota and Mypolonga.

The flood watch and act message urged residents to prepare for evacuation.

A map of the latest flood warning area along the River Murray. The state government forecasts the flood peak will reach Murray Bridge between January 6 and 17. Image: SES

“There is a high risk of flooding for low-lying areas of Younghusband, Mannum, Caloote, Pompoota and Mypolonga, due to rapid river level rises, that may threaten your safety,” the SES warning said.

“Regardless of your property’s ability to withstand flood impacts, there is a chance you may become flooded or isolated.

“If you remain in the area you may become trapped without water, power and other essential services.

“You should now prepare to evacuate. If the situation worsens it may not be safe to leave. It may be too dangerous for emergency services to assist you.”

It comes after residents in Walker Flat further upstream were told last night to evacuate immediately. By early Thursday, all residents in the town had left except one who had elected to stay, according to the SES.

A watch-and-act message is also in place for a 40-kilometre stretch of the river further upstream, taking in Caurnamont, Purnong and Bowhill.

The state government today said the floodwater peak is still predicted to be between 190 and 220-gigalitres a day. It is due in Renmark between December 24-31.

Authorities predict the flood peak will hit Berri between December 25 and January 5, Waikerie between January 1-12, Swan Reach between January 5-16 and Murray Bridge between January 6-17.

The government says river communities should consider those dates when preparing for the flood emergency and factor in potential road closures and ferry closures, as well as disruptions to the power network and reduced services.

Authorities also warned today that a levee failure in NSW could push Murray River flood levels higher in South Australia.

The breach, near Lake Victoria in the southwestern corner of New South Wales, could prevent the diversion of up to 10 gigalitres from the Murray.

SA State Emergency Service Chief Officer Chris Beattie said work was underway to try to repair the levee but if that was unsuccessful the extra water would flow into SA.

“Part of that lake system provides an avenue for us to divert water and the intent has always been to divert five to 10 gigalitres into Lake Victoria,” Beattie told reporters today.

“Obviously, that knocks the edge off the peak flow. If they can’t repair the levee … then we may see a lack of capacity to knock that five to 10GL off the peak.”

Beattie said it was uncertain whether repairs could be achieved and still retain the ability to divert flows.

The SES said a number of other levee failures had been dealt with including incidents south of Renmark, near Barmera and at Port Mannum.

A failure of the levee protecting the caravan park at Kingston on Murray had also forced the evacuation and closure of the park.

More than 1100 Riverland properties have so far been inundated with water, with the number tipped to hit 4000 when flooding is expected to peak later this month.

The SES estimates that 255 businesses and 4000 hectares of agricultural land will also be impacted by the flooding by the end of this month.

– with AAP