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Lake Benalla to be drawn down to get rid of weed

Monday 8 January, 2018
The water level in Lake Benalla will start to be drawn down during the last week of January to help get rid of the aquatic weed cabomba.

Goulburn Broken Catchment Management Authority (CMA) Project Co-ordinator Tim Barlow said as well as smothering native aquatic vegetation that provided valuable habitat for animals, fish and waterbugs, cabomba also clogged pumps and filters.

“It also seriously compromises the aesthetic and recreational value of waterways and wetlands and poses a real water quality hazard to people and animals,” Mr Barlow said.

 “Lowering the lake for a couple of months will expose the weed to air and dry it out. This is the most effective and efficient way to get rid of cabomba and is safer than using sprays or other chemicals. Lowering of the lake has been successful in the past and has reduced the weed population significantly.  Back in 2007 cabomba covered the majority of the lake, causing major issues for the town. Today it’s at a manageable level. Drying it can reduce this again.”

Goulburn Broken CMA and Benalla Rural City Council have been in contact with a range of groups and lake users to discuss timing of the drawdown. A survey of the lake’s platypus population will be done before and after the drawdown, with the public invited to attend a spotlight walk mid-January.

“A small channel of water – the original course of the Broken River before the lake was created - will remain, which will help native animals, fish and other creatures move to other sections of the river while the level is being lowered,” Mr Barlow said. “It will also be a good opportunity to remove any rubbish and debris that has been dumped or washed into the lake over the past few years.

 “On-going diligence is required to prevent its re-establishment so we are keen to control the weed to protect irrigators’ and lake users’ interests as well as significant wetlands such as Winton Wetlands and the Barmah National Park downstream on the Broken Creek.”

Cabomba is an introduced plant that is often used in aquariums. It has fan-shaped, brownish ferny leaves that sit mostly underwater, with a white flower floating on the surface.  To prevent further infestations, it is essential that aquarium plants be composted and not disposed of in or near waterways. 

Goulburn Broken CMA is working with Benalla Rural City Council and Goulburn-Murray Water on the project, which is funded by the Australian Government’s National Landcare Program.

More information can be found here.