Murray crossing a challenge for many in SA

Crossing the Murray in South Australia is becoming a challenge for locals as surging river flows continue to shut down ferry services.

In the latest move, all ferries between Morgan and Mannum have now been closed.

The ferry at Cadell continues to operate and other avenues to cross the swollen waterway include the road bridges at Blanchetown and Murray Bridge.

The State Emergency Service says the high water mark will reach Blanchetown, Swan Reach and Mannum this weekend.

"Communities should expect to see and prepare for new areas of flooding," it said in its latest warning.

Peak flows are also expected to reach SA's Lower Lakes by January 13, a little earlier than originally expected, but water levels have begun to recede in the state's Riverland.

Flows across the border are down by about 30 gigalitres a day and are likely to drop by up to 60GL by early February.

So far, more than a dozen levees across the river system have failed or had major issues, but almost all have been those protecting agricultural land.

Levees protecting towns have mainly held firm.

On Thursday a helicopter was deployed to drop large sandbags to reinforce a levee protecting critical water supply infrastructure east of Adelaide after inspections at Cowirra near Mannum revealed serious erosion.

The chopper dropped about 200 Bulka Bags, each weighing up to 1000kg, in the day-long operation.

Also on Thursday, the state government opened a third emergency relief centre at Murray Bridge following others at Berri and Mannum.

The centres provide easy access to support services, including hardship grants, food relief, emergency accommodation and financial and personal counselling.

So far, the Berri and Mannum relief centres have helped more than 1600 people.

The Murray flooding has impacted about 3400 properties, including nearly 400 primary residences. It has closed 119 roads across river communities with nine ferries out of action.