Thirty years ago, Merline Thykeson, owner of Mark’s Marine Inc. and lake resident, could look off his dock and admire the clear water and sandy lake-bottom of Hayden Lake. Today, a forest of weeds growing from silt and decay separates him from the sand.
This is the story told by Thykeson and other Hayden Lake Watershed Association members seated at the table with state and local agency representatives on Friday, March 8 at the first Hayden Lake Weed Management Workshop, convened by the association to formulate a collaborative plan for weed management on the lake.
Present at the meeting were representatives from Idaho Department of Lands, Idaho State Department of Agriculture, Idaho Department of Environmental Quality, Kootenai County Sheriff’s Office, the Kootenai County Commissioners, and the Hayden Lake Watershed Improvement District.
Only the day before, the improvement district hosted a meet-n-greet with the Idaho State Department of Agriculture to inform interested parties about spring plans to treat noxious weeds on Hayden Lake. A full house of lake residents learned the state agriculture department will drive back curly leaf pond weed from the lake’s northerm arm using fluridone, a chemical herbicide that does not restrict drinking water-use but does involve irrigation restrictions at the concentrations used. Treatments will start in May.
A second treatment phase specific to Eurasian water milfoil will take place later in the summer. Attendees were also eager to find alternatives to chemicals for managing invasive weeds, a sentiment the agriculture department shares.
Geoff Harvey, a lake resident, summarized the situation, explaining that invasive and native aquatic weeds grow heavily in the shallow northern arm, Mokins Bay, and O’Rourke Bay, encouraged by the lake’s nutrient-rich substrate. In 2018, invasive weeds spread to shallow areas throughout the lake, increasing the nuisance for non-resident lake users and lakefront owners alike. The props of ski and fishing boats are believed to be the mechanisms for propagation and transmission of weeds.
Representatives from Kootenai County Sheriff’s Office added that heavy weed growth in the lake’s northern arm inhibits their ability to patrol and safeguard that part of the lake. It also restricts Northern Lakes Fire Protection District’s ability to move its fireboat to the northern shores.
Bob Steed with the Idaho Department of Environmental Quality pointed out that weed-infested areas are most susceptible to toxic blue-green algal blooms. Steed said he has observed boaters recreate in infected water without realizing they are doing so.
Everyone present acknowledged that the high level of aquatic weed growth in the lake is a hindrance to recreational use, sustainable living, and safety on the lake.
The Hayden Lake Watershed Association presented a plan to minimize the nuisance aspect of the weeds, to prevent further spread, and which would benefit safety and water quality. The plan includes supporting the state agriculture department’s work and adding harvesting or skimming to remove weed mass from the lake; testing the development of a weed-free travel corridor through the contaminated north arm; and directing some water sports toward the main body of the lake, away from the weed-impacted shorelines.
County Commissioner Leslie Duncan encouraged prioritizing the components of the plan, employing a phased implementation, and public involvement in planning and implementation.
Thykeson offered his support of the plan.
“I’m not in favor of preventing any kind of recreation on the lake,” Thykeson said. “But some means of limiting weed spread down into the main lake by boats and the wind must be achieved if we’re going to be able to continue using the lake in the future.”
The Hayden Lake Watershed Association and the Hayden Lake Watershed Improvement District work in concert to preserve and enhance the quality of the water and the environment of the watershed through lake monitoring and public education. Find more information regarding Hayden Lake, weed management, and water quality at https://haydenlakewid.com.
— Submitted by Mary Ann Stoll, communication and outreach director for the Hayden Lake Watershed Improvement District.