🌊 Floods

Which Lower Murray levees should hold and which will be tested?

The Mypolonga community are confident that a levee will protect their primary school from the coming floods, but many low-land farmers may not be so lucky.

Michael X. Savvas, Peri Strathearn

Dec 15, 2022 — 4 min read

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Work continues on the levee to protect Mypolonga Primary School and surrounding homes. Photo: Michael X. Savvas.

A 530-metre-long and two-metre-high levee is being built below the Mypolonga Primary School and several nearby homes.

Staff and parents at the primary school are continuing to ensure their school’s safety.

Sunyl Vogt, principal of Mypolonga Primary School, said he felt comfortable that the school would be safe due to the strong support from the community and the Department for Education.

“We were a bit worried about whether the levee would come together, but now that it is, the community on the whole is feeling comfortable,” he said.

“No-one’s clear on what we’re going to see in coming weeks, but with the levee, there’s a lot more comfort.

“At the school, we’ve moved stuff from one of our sports sheds and will do the same in our upper primary building.

“We’ll be sandbagging these areas on Saturday and shifting any furniture of great value.

“Families will come in and fill sandbags, and the Mypolonga Progress Association will help out, too.”

Ash Martin, whose contracting company is working on the levee below the school, said that the completion of the levee was on schedule.

“The water looks like it’s coming in quicker than expected, so we have to have it done before the flows get here,” Mr Martin said.

“We’re aiming to finish it by early to mid next week.

“The levee will be three and a half metres above sea level and be three metres wide on top to allow for any future increase.

“I think we’ll be right.”

For the main levee along the riverfront, however, the outlook is not so positive.

Most riverfront levees at risk of inundation, DEW data suggests

Department of Environment and Water data suggests that most of the levees along the River Murray between Woodlane and Wellington will be severely tested in the coming weeks.

Of the 10 government-owned levees in the Murray Bridge and Coorong districts, five – those at Wall Flat, Mypolonga, Pompoota, Mobilong and Murray Bridge East – had gaps below the 1974 flood level when they were surveyed by DEW recently.

The coming floods are projected to exceed that level by about half a metre in Murray Bridge.

Two more levees – those at Long Flat and Jervois – had crests close to the projected flood peak.

There are also 15 private levees along the same stretch of river, most of which were well below the anticipated flood level when DEW last surveyed them in 2011.

A Department of Environment and Water spokesman said the government levees had been “intensively” maintained in recent months to ensure they were in the best possible condition.

Earthen Levee Embankment Inspection and Repair Guide1.61MB ∙ PDF fileDownload Download

“We have confidence in their performance in a flood event up to the levels and flows for which they are designed,” he said.

“It's important to note, however, that even if structurally sound, levee banks can only perform their role up to that designed level.

“This is the first time in nearly 50 years that River Murray flows have reached many areas of the landscape and it is almost certain that changes to the river channel and floodplain in that time will lead to some unforeseen and unexpected differences in flood behaviour.”

The department would continue to carry out site inspections and surveys of its levees, he said.

All government levees have been closed to the public since November 21.