Weed woes require new low
Lake Mulwala will be lowered by 4.5 metres, a metre more than originally targeted to ensure effective weed control for the local community and the lakes’ recreational users.
Murray–Darling Basin Authority (MDBA) head of River Management, Andrew Reynolds, said new information gathered from a survey of the extent of the highly invasive aquatic weed Egeria densa in Lake Mulwala has found that the weed is present at greater depths in the lake than previously thought.
“The original plan to lower the lake by 3.5 metres would not have exposed weed in these deeper locations,” Mr Reynolds said.
“We have reviewed and considered this new information. To ensure the draw down is as effective as possible, with the best outcomes for the local community and recreational users; we have revised the draw down to 4.5 metres below normal operating levels, which is a metre further than originally planned.
“By lowering the lake further we can target a greater portion of the aquatic weed which was impacting on the lakes’ usage, making it harder to swim, fish, launch boats and water ski.
“The lake draw down continues with the lowering to reach 3.5 metres by the end of May, as originally planned. The water level will then continue to reduce in the first few days of June until Lake Mulwala is 4.5 metres lower than normal.
“We expect to hold the lake at this level until mid-July when refilling will start, bringing the lake back to its regular operating levels by early August.
“The draw down will be managed so that it poses minimal risk of impacting on available water resources in the coming season.
“The lowering will expose muddy lake flats. This will make it difficult to access the water’s edge and reduce the ability to launch boats from the boat ramps. “People will still be able to boat and fish in the main river channel that runs through the lake but will need to launch their boats upstream,” Mr Reynolds said.
Last year GMW and the MDBA released the Waterweed Wipeout app. The tool is designed to help the community better understand the management techniques used to control the invasive weed. Waterweed Wipeout is free and available from the App Store and Google Play for Apple and Android phones and tablet devices.
An empty Lake Mulwala exposes the invasive aquatic weed to frosts which assists in controlling its growth.