Lake Wanaka Weed Control Update

8 September 2008

The effort to control the introduced lakeweed lagarosiphon in Lake Wanaka continues to show good progress, the Lake Wanaka Lagarosiphon Managers Committee said today.

Spokesperson Russell McGeorge said lagarosiphon was well under control at all sites north of Roys Peninsula, and in Paddock Bay.

The easily spread invasive oxygen weed forms dense weed beds up to several metres deep that clogs up shallows and smothers native plants.

Land Information New Zealand (LINZ) carries out the control work in consultation with the Managers Committee, which comprises representatives from Queenstown Lakes District Council, Guardians of Lake Wanaka, Otago Regional Council, Department of Conservation and LINZ.

"We've given high priority to controlling the weed's spread north of Roys Peninsula and we're on track to achieving this. It's at the point where hand-weeding is all that is required to keep regrowth in check at these sites," Mr McGeorge said.

"This means resources can now be focused on weed beds south of Roys Peninsula. Monitoring by the National Institute of Water and Atmospheric Research has confirmed the excellent results that are apparent in Paddock Bay, and we've also had encouraging results in Glendhu Bay and in Stevensons Arm."

LINZ's Bill Naik, Manager of Crown Property Management, said the progress to date was very encouraging.

"We're three years into the 10 year programme that was formulated with community input in 2005. There's still a big task ahead at the southern end of the lake, and lake users can help by checking and cleaning their recreational equipment and boats to ensure weed fragments are not being transported around the lake or indeed to other lakes."

Three approaches to control are being taken in the lake - handweeding, suction dredging and applications of the aquatic herbicide Diquat which is used to knock down dense infestations to manageable levels.