U.S. LAKESHORE RESIDENTS SAY PLANS FOR HERBICIDE USE ABOUT NEED TO ERADICATE MILFOIL
OSOYOOS TIMES-August 3, 2011
By Paul Everest – Osoyoos Times
Controlling Eurasian milfoil on the Canadian side of Osoyoos Lake has for years meant harvesting the plant in the summer and rototilling in the fall and winter.
While these activities help keep the pesky plant trimmed and away from the surface of the water where boaters and swimmers play on our side of the 49th parallel, some lakeshore residents in Washington state feel the harvesting and rototilling is behind a number of problems in their half of the lake.
Mike Cantwell and John Moran live along the west side of the lake south of the international boundary.
They are also members of the Lake Osoyoos Association, an Oroville-based organization that resembles the Osoyoos Lake Water Quality Society in its aim to monitor and protect lake-water quality.
In 2010, they said, the southern portion of the lake was plagued with “floating mats” of milfoil which they, and some other lakeshore residents, believe drift down from the Canadian side after harvesting activities take place.
The mats, Cantwell and Moran said, are so thick in places that some people are having trouble launching boats or enjoying other recreational activities on the water.
Some of the worst places for the mats, they added, are around new residential developments on the lake’s American shores which are owned, ironically, by a large number of Canadians.
Since they believe Canadian milfoil management practices are causing such problems in American waters, Cantwell and Moran said, lakeshore residents in the U.S. don’t just want the troublesome plant managed better, they want it eradicated.
That’s why a number of residents approached the Okanogan County Noxious Weed Control Board (OCNWCB) earlier this year and asked the board to apply to the Washington state Ecology Department for permission to use a granular herbicide in Osoyoos Lake to kill the milfoil.
A spokeswoman for the department said approval to use herbicides in the lake has not yet been given and it could be some time before the department gets around to considering the board’s application.
In the meantime, however, the board’s application has sparked a media storm on both sides of the border.
Last month, the Osoyoos Times reported that the Okanagan Basin Water Board (OBWB), a B.C.-based organization focused on dealing with water issues in the Okanagan watershed, sent a letter dated July 11 to the OCNWCB asking it to reconsider its plan to use an herbicide to control milfoil in the U.S. part of the lake.
In the letter, Stu Wells, the OBWB’s chair and mayor of Osoyoos, argues that “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.”
American media are also reporting that the provincial Environment Ministry has also asked the OCNWCB to consider alternatives to herbicides but the Times was not able to verify this before press time.
While sympathetic to Canadian concerns, Moran said the herbicide that is being considered, Triclopyr, has been successful in battling milfoil on other American lakes.
If the department allows for its use, he added, the timing of the application of the herbicide would take into account fish runs and local irrigation schedules.
He and Cantwell also said they see no merit in the concern that herbicide used in the U.S. side of the lake could end up back in Canada since the water in the lake flows south.
Even if there was a rare flooding event where water in the south part of the lake backed up into Canada, they said, a policy would be put in place to prevent herbicide application when there is a flood risk.
Continuing with rototilling and harvesting will just allow the plant to continue to prosper, Cantwell and Moran said, since, even though most of the harvested and rototilled parts of the milfoil are collected, some pieces do escape and are capable of creating new milfoil colonies elsewhere.
Cantwell said any boat with a propeller also acts like a harvester and tears up and redistributes the plant throughout the lake.
While Cantwell and Moran, as lakeshore residents, want to see the milfoil eradicated, Cantwell said the Lake Osoyoos Association has not endorsed the use of herbicides for treatment in the lake and would prefer a biological approach to the problem.
Along with pushing out native plants from the lake and depleting oxygen levels in the water that can limit the areas where fish can live and travel, thick strands of milfoil also pose a safety hazard for swimmers and boaters.
Cantwell, Moran and the OCNWCB point to a handful of recent deaths in Washington state blamed on milfoil as one more reason to eradicate the plant.
Many other lakeshore residents agree with them, according to a survey sent out by the OCNWCB.
Anna Lyon, the board’s manager, said 50 people responded to 220 surveys sent out earlier this year.
Although five respondents to the survey indicated they would prefer other ways to control milfoil, the rest were supportive of using herbicide.
While the board has stated that it is looking at other ways of fighting milfoil, including the use of weevils, an insect that feeds on milfoil, Lyon said it intends to go ahead with its plans to use herbicide in the lake once it receives state approval, despite the OBWB’s concerns.
As for the weevil option, Moran said it would be great if weevils could be brought in instead of herbicides, but right now buying enough weevils to control the milfoil is too expensive.
The OBWB, which signed a memorandum of understanding in February with a number of U.S. organizations to share information on invasive plants and weeds such as milfoil, does not have many options on how to deal with the OCNWCB’s plans at the moment, said Anna Warwick Sears, the OBWB’s executive director.
She said the OBWB is waiting to see what will happen with the OCNWCB’s application and is not considering any legal action at this time.