Boaties and visitors to Central Otago lakes are being asked to ‘Check Clean and Dry’ all the gear they use in lakes and rivers as the summer season begins.

The invasive water weed lagarosiphon is well established in Lakes Wānaka and Dunstan. It’s building up in the Kawarau River and is more regularly being found and removed during monitoring of Lake Wakatipu.

Left uncontrolled lagarosiphon smothers our native underwater plants. It can take over lakes and create dense forests of sludgy weed on the water’s surface, blocking boat motors and ruining swimming.

Checking, cleaning and drying boat props and trailers, jet skis, kayaks and paddleboards, and fishing gear before and after they enter the water limits the spread of lagarosiphon and other invasive weeds. 

Toitū Te Whenua Land Information New Zealand is the lead agency responsible for controlling the invasive lake weed across Central Otago waterways. Toitū Te Whenua biosecurity and biodiversity manager Tracey Burton says users need to think about the risks to the environment when moving between lakes and rivers.

“We’re so lucky to have beautiful lakes and rivers in our backyard where we can have fun and enjoy nature. These waterways are connected and our actions in one area can impact the whole lake and river system. That’s why we all need to do our bit to Check, Clean and Dry when moving between waterways.”

Boaties, fishers, tourism operators and recreational users of Lake Wānaka are also being asked to be extra careful this summer to avoid damaging biodegradable matting installed in parts of the lake. 

Hessian matting has been laid at a number of new sites around the edges of Lake Wānaka. The matting suppresses lagarosiphon while at the same time allowing native plants to grow through.  

Tracey said hessian matting is an invaluable tool in the fight against lagarosiphon in Lake Wānaka but it needs to be protected.

“We’re asking all lake users but especially people fishing and boating in these areas to avoid the matting where possible or take extra care not to disturb the matting in areas where it is laid,” she said.

Around 20 red and black marker buoys are in place in Lake Wānaka to mark areas where new and recently maintained hessian matting is in place, close to shore at Paddock Bay, Sandspit, Glendhu Bluff Bay (including Emerald Bay), Parkins Bay, and Fern Burn (between Parkins Bay and Glendhu Bay).

Tracey said “whether you’re dipping in Dunstan, whooping it up in Wānaka or kicking about in the Kawarau” it’s important you help protect and get behind lake restoration efforts.

“The presence of lagarosiphon and the risk of infestation from other water weeds such as hornwort poses a very real and serious threat to the future of Otago’s lakes,” she said.

“We use our lakes and rivers to kayak, swim, boat, water ski and take scenic trips. They are vital economic assets, supporting electricity generation and the tourism industry throughout the year and we can’t take them for granted.”

Advice on how to effectively clean equipment to remove weeds is available here and the Otago Regional Council’s Check, Clean, Dry campaign advocates will be out and about again this summer. Read more about the Toitū Te Whenua annual biosecurity programme here.  

PHOTO: Wānaka App