Workers are today removing the barrier that held back up to three metres of river flood water to protect lakeside cultural sites and nearby Barmera homes from flooding and wastewater backups, but which also triggered algal outbreaks that impacted boating, fishing and swimming.

Lake Bonney’s usually bustling tourist accommodation park closed hundreds of sites in early November, along with removing 20 cabins at risk of flooding.

Discovery Parks was now monitoring water levels to get “the park back up and running as soon as possible”.

“We made the difficult decision to close the park in early November due to rising floodwaters in the region and moved quickly to minimise the potential impacts of flooding by building a levy on the lower side of the property that fronts the lake and removing 20 cabins that were most at risk,” a company spokesperson said.

“It’s been a challenging time for us at the park as we have more than 220 tourist sites and 80 cabins that we had to close to tourists, and these would be anywhere from 80 to 90 per cent full over the December and January period.”

In the meantime, the park has helped accommodate some tradespeople and contractors working in the region to support the community’s flood preparation and management works.

Locals are looking forward to tourists returning to Lake Bonney in Barmera. Photo supplied.

Berri Barmera Mayor Ella Winnall said it was a huge relief for the town to be reconnecting Lake Bonney to the river system today, having previously raised concerns about the closure deeply impacting local businesses as tourists stayed away.

“For other towns on the river, having the peak come and the water start to recede was a big turning point for them, but Barmera has been waiting until today to have that same sense of relief,” she said.

Authorities closed the River Murray inlet to the lake as projections showed about 4000 people would have been impacted by flooding along with the Morgan Road Bridge, known as Nappers Bridge.

Today as the inlet is reopened, State Coordinator Grant Stevens issued a direction prohibiting people from being on or in the River Murray, including Lake Bonney, within 500 metres of the Morgan Road Bridge.

Lake Bonney’s River Murray inlet is being reopened today. Photo: Ella Winnall

Downstream irrigators are also being warned salinity levels would likely be affected by the reopening of the levee at Nappers Bridge that held back almost three metres of flood water at its highest point, and to monitor salinity data via SA Water.

The latest Environment and Water Department (DEW) flow report said it was common as flood waters fall to see rising salinity levels, as normally higher salinity water held in Lake Bonney is drawn into the river.

“Modelling undertaken by DEW has indicated that salinity in the river channel should stay within limits for consumptive use,” the report said.

Emergency Services Minister Joe Szakacs said the decision to reopen the lake to the River Murray comes as water levels across the state continue to fall.

Community waste management systems, storm water infrastructure along with private properties and businesses were now deemed “at minimal risk of damage”.

State Emergency Service chief officer Chris Beattie said reopening the Napper inlet was a key priority as flood waters receded to a safe level.

“Lake Bonney is a popular destination for South Australians and allowing the flow of fresh water into the lake will provide ecological benefits for fish and vegetation, but also for the local community,” he said.

Berri Barmera Council acting chief executive officer Tracey Alexander said the local community proved resilient over the eight-week closure and would now welcome the fresh river water entering the lake.

“Lake Bonney is truly at the heart of our community, and with the reconnection of the lake to the river, our lake can receive a flush of fresh water, and all the benefits that brings.”

The council has worked with the River Murray Mallee Aboriginal Corporation to understand cultural impacts of the reopening, and how these can be managed.

Most recent modelling predicts River Murray flows at the border will fall about 45GL a day from February 3 to February 10.

“This is a steeper rate of fall than has been experienced up until this point and water users should take care and regularly check their boat moorings to make the necessary adjustments,” according to the Environment and Water Department flow report.

The flow at Lock 1 is expected to fall to 100 GL per day around February 10 and continue to fall rapidly to 60 GL per day within the following week.

River flow is forecast to return to the main channel at around 40 GL per day during February, but many low-lying areas of the floodplain are expected to remain inundated for an extended period.