SA Health announced on Sunday afternoon that the River Murray had reached a pre-determined level triggering the relocation of 21 vulnerable residents from the hospital.

The move is the “first phase” of the local health network’s relocation plan, SA Health said, with the hospital accommodating another 60 aged care residents.

The 21 residents will begin to be moved to other local facilities from Tuesday as a “precautionary measure”, chief executive of the Riverland Mallee Coorong Local Health Network (LHN) Wayne Champion said.

“These 21 residents are not independently mobile and require the highest level of care and it is important that time is given to ensure relocation is done in a careful, controlled, and safe manner,” Champion said.

The Riverland is bracing for daily River Murray flows of 175 to 180 gigalitres to come down on December 14 with the potential to inundate 3500 to 4000 properties throughout the state.

It is likely to be Renmark’s biggest flood event since 1956.

Up to 4000 properties in SA are expected to be affected, 450 of which are considered permanent residences.

“Riverland Mallee Coorong LHN has a high level confidence in the work the Renmark Paringa District Council has completed in strengthening the hospital levee,” Champion said.

“However, we have a number of vulnerable aged-care residents who are mobility impaired in the Renmark Paringa District Hospital’s aged-care facility, who would be difficult to evacuate quickly, with a staged relocation the much preferred option.”

Champion also said part of the reason for relocating residents “at this early stage” was that the process “will not impact SA Health acute services, over a three to five day period”.

Chief public health officer Nicola Spurrier said the chances floodwaters enter the Renmark Paringa District Hospital are “very very low”.

“The levee around the hospital is probably the strongest and widest levee in the state,” she told ABC Radio this morning.

“It’s been significantly reinforced recently, there are engineers that go and review the levee to check that it’s all in place on a daily basis.

“So we feel very confident that the asset of the hospital is very well protected.”

Spurrier said the local health network would continue to monitor the height of the River Murray over the coming weeks before making a decision on whether to relocate more residents.

“The next group of residents are a little bit more mobile,” she said.

“We’ll just see how we go with moving this first group and then make a consideration as at the end of the week or early next week about the next group.”

Spurrier said the most mobile group of residents at the hospital may not need to be relocated at all.

State Emergency Service chief of staff Graeme Wynwood said he was confident work undertaken to strengthen existing flood levees across the Riverland would help protect the community.

“SASES in collaboration with local councils have commenced work on installing temporary barriers at key agreed sites in Berri, Barmera, Renmark, Murray Bridge and Mannum using the new DEFENCELL system for the protection of properties and key infrastructure,” he said in a statement.

“We are commencing some work on installing a section of flood barrier at Berri Barmera near Lake Bonney [on Monday]. Installation of flood barriers to protect community infrastructure at Murray Bridge is complete.”

Prime Minister Anthony Albanese and Premier Peter Malinauskas visited Renmark on Saturday to help reassure locals and monitor preparations.

Emergency services are door-knocking around 3500 homes along the River Murray to check if residents are safe.

Malinauskas said on Friday: “I think we’re in the best possible spot we can be, given the difficulty of the circumstances.”

“The tragedy is, there’s nothing we can do to stop this water coming.”

-with AAP