Weed Control Planned for Paddock Bay, Lake Wanaka

3 November 2006

Further control of the aquatic pest weed Lagarosiphon using the herbicide diquat is planned for Paddock Bay, Lake Wanaka.

The Lake Wanaka Managers' Committee's weed control programme has shown very good results to date, said Land Information New Zealand (LINZ) spokesperson Paul Jackson. "But we need to go back to Paddock Bay with diquat where a weed mass covering approximately 20 hectares is close to reaching surface levels."

The window for the control work, which requires one to two days to complete and depends on weather and lake conditions, begins on Monday 20 November.

If the work is not possible then, it will take place on the next suitable day, with the exception of weekends and public holidays, until Friday 8 December. If the work cannot be carried out it will be deferred until after the summer.

Mr Jackson said the Committee hopes that targeting the weed now will keep the weed in check over the summer holidays. Without treatment, the weed will affect users' enjoyment of the lake and could also spread to other areas of Lake Wanaka.

The Paddock Bay work follows previous mechanical and hand weed control on Lake Wanaka in 2006, and diquat applications in December 2004 and May 2005. "This controlled the weed so successfully that we haven't had to use the herbicide again until now," Mr Jackson said. "To continue that success, we may need to follow up this latest application with a second hit in March 2007."

Mr Jackson acknowledged there may be some public concern about applying herbicide in the lake. "Diquat has been used in New Zealand lakes for more than 40 years and has proved safe and very effective in controlling aquatic weeds. Given the extent of the problem in Paddock Bay our best option is to knock the weed down with herbicide."

"The Committee advises people not to use Paddock Bay when the herbicide is being applied, and also asks the public not to take drinking water or water for irrigation from the Bay until 24 hours after the treatment."

Mr Jackson also urged boaties to do their bit to prevent the spread of Lagarosiphon by checking their boats, trailers and other equipment.

Public notices about the weed control work will appear shortly in the Otago Daily Times, Southland Times, Wanaka Sun, and air on Radio Wanaka. On the day of the application, signs will be erected at major public access points near areas being treated with herbicide.

Daily updates will be posted on the LINZ website: www.linz.govt.nz

The Paddock Bay control works are part of a 10-year plan to control the spread of the weed in Lake Wanaka. The plan is overseen by the Lake Wanaka Managers' Committee, which is comprised of: Queenstown Lakes District Council, Otago Regional Council, the Department of Conservation, the Guardians of Lake Wanaka, and Land Information New Zealand.

Copies of the National Institute of Water and Atmospheric Research reports on the mechanical and hand weeding control works programme are available.

For further comment please contact:

LINZ media liaison:

Julia Hodge
Communications Adviser
Land Information New Zealand
Tel 04 498 3502
Email: jhodge@linz.govt.nz

Dave Chowdhury
Senior Communications Adviser
Land Information New Zealand
Tel 04 496 5402
Cell 027 222 9566
Email: dchowdhury@linz.govt.nz