21 January 2023

Water monster monitored in Eurobodalla to ensure it does not return

| Albert McKnight
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Salvinia is scooped from a Eurobodalla dam during council’s efforts to eradicate the weed. Photo: ESC.

It took years for Eurobodalla Shire Council to bring a monster in its waterways under control, which is why staff will soon be on the lookout for the pest to ensure their efforts were not in vain.

Salvinia molesta, also called giant salvina, is a fast-growing, floating water weed originally from Brazil which can take over waterways and reduce water quality, NSW WeedWise says.

Due to how it forms in dense mats, it can smother the water’s surface. This has a range of consequences for our environment, including preventing native water plants from growing and reducing food and habitat for aquatic life.

It can also prevent the use of waterways by humans, as well as block irrigation channels.

“It can double in size in less than three days in ideal conditions,” WeedWise says.

“It has been sold illegally as an aquarium plant and sometimes found in aquariums and fishponds.”

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Salvinia was first spotted in a one-hectare dam at Sunshine Bay, in Batemans Bay, in 2011.

Council’s invasive species supervisor Paul Martin said removing it was “incredibly resource intensive, laborious and dangerous”.

“We spent the best part of 10 years spraying by hand, from a helicopter, releasing biological control, removing it with an aquatic excavator, and hand-scooping it from the complex wetland environment,” he said.

He said salvinia would have been disastrous if it took over the shire’s drinking water supply.

A Sunshine Bay dam full of salvinia seen from the air in 2012. Photo: ESC.

“There was a significant risk to our water supply if a waterbird carried salvinia to Deep Creek Dam,” Mr Martin said.

“It’s important to protect our drinking water. By doing future inspections we can make sure salvinia does not exist in our catchment.”

The invasive species team will be performing inspections in Sunshine Bay and Denhams Beach in February and March to check salvinia hasn’t made a comeback.

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Landholders and council have a legal obligation under the Biosecurity Act 2015 to stop the spread of the weed. Landholders have been notified of the upcoming inspection.

“There’s no need to be home for the inspection; our invasive species team will do a quick inspection and report back to you if we find anything of concern,” Mr Martin said.

The dam at Sunshine Bay when it was free of salvinia in 2019. Photo: ESC.

The team will also check for other serious water weeds such as water hyacinth, horsetail and alligator weed.

For more information, contact Paul Martin on 4474 1000 or [email protected].

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