OKANAGAN BASIN WATER BOARD ASKS U.S. WEED-CONTROL ORGANIZATION TO RECONSIDER USE OF HERBICIDE IN FIGHT AGAINST MILFOIL IN OSOYOOS LAKE
OSOYOOS TIMES-July 13, 2011
By Paul Everest – Osoyoos Times
The Okanagan Basin Water Board (OBWB) is asking a Washington state-based organization focused on weed control to reconsider its plans to use an aquatic herbicide to control milfoil in the U.S. portion of Osoyoos Lake.
In a letter written by OBWB chair Stu Wells to the Okanogan County Noxious Weed Control Board (OCNWCB) dated July 11, the OBWB requested that the OCNWCB not use such an herbicide to kill Eurasian watermilfoil in the part of the lake south of the international boundary.
The OBWB also asked the OCNWCB to work with local residents living around the southern part of the lake to find other ways to control the milfoil.
If the OCNWCB goes ahead with its plans to use herbicide in the lake, the OBWB argues, “the hydrology of Osoyoos Lake and the back-swelling Okanagan River would make it possible for chemicals applied south of the border to mix into the northern half of the lake.
“The potential risks to the ecosystem, drinking and agricultural water intakes, residents, and visitors on the Canadian side of the lake are unknown and may violate the Boundary Waters Treaty.”
Wells also states in the letter that the treaty does not allow for shared waters to be polluted in a way that could harm people or property on either side of the border.
The OBWB also suggests several alternative forms of milfoil control including harvesting, rototilling and hand-pulling by divers.
“Biological control through augmentation of native insects might also hold promise.”
Anna Lyon, the manager of the OCNWCB, said the reason her board is planning to use an herbicide to battle milfoil in the lake south of the border is due to pressure from lakefront property owners around the southern end of the lake who are complaining about spots in the water where the milfoil is thick.
The OCNWCB applied earlier this year to the Washington state Ecology Department for permission to use an herbicide for milfoil control, she said, and despite the OBWB’s letter, her board intends to carry out its plans to use the herbicide in the lake.
The OCNWCB has not received the department’s approval yet and the OBWB’s letter was forwarded to the department, Lyon said.
She added, however, that the herbicide would only be used in a limited way in a few areas up to four hectares in size.
Those areas, she said, are far away from the border.
She also said her board is looking at other ways to deal with the milfoil problem in the lake, including the use of weevils and possibly requesting the use of the OBWB’s milfoil harvester which is used in the Okanagan Valley.
Ultimately, milfoil is a huge public safety issue in Washington state waters and several deaths in the past year have resulted from swimmers becoming caught in the plant, Lyon said, adding that her board has been receiving complaints about the plant for roughly 10 years.
The OBWB has been working to control milfoil, an invasive species introduced to North America in the 19th century, in the Okanagan basin since the 1970s and currently uses a harvester to trim the plants near the surface in the summer and rototill the roots of the plants in shallow places in the fall and winter.