Lake Chelan, Roses Lake to receive a check-up

Roses Lake, 2024. Considered the worst algae bloom in the Manson lake

Lake Chelan water quality and levels of pesticides in lake water will be analyzed in coming months.

An environmental testing firm, Eurofins Knoxville, plans to take 13 samples from the lake under terms of a $15,000 contract with Chelan County Natural Resources.

"One of the long term sources of DDT into the lake and frankly if there's anything that can be done," is how Chelan County Natural Resources Director Mike Kaputa described the focus of the new check-up to Chelan County Commissioners on Monday.

"We're trying to figure out how it's (DDT) getting into the lake and is there anything we can do about it. It's possible that we could do a fair amount of analysis here and determine that there's really not much we can do."

"The biggest issue on Lake Chelan with DDT has nothing to do with water quality or water supply, it's all about the lake trout," said Kaputa. "Those guys are top of the food chain, they're all of the little critters that are taking in the DDT, so there is a health advisory for lake trout on Lake Chelan."

Periodic algae blooms in Roses Lake in Manson will also be investigated in coming months. A Washington State Department of Ecology grant will pay for Geosyntec, an environmental consultant group, to join ecology and county staff with developing a Quality Assurance Project Plan for monitoring lake conditions as well as its primary inflows and outflows.

The Lake Chelan Collaborative, with interest in Roses Lake, and lake landowners were involved in selecting the consultant to assist the county, which will do the lake water monitoring.

Lake water temperature, dissolved oxygen, and pH will be checked. Turbidity at the deepest point using a Secchi Disk Nutrient, and chlorophyll-a, and phytoplankton samples will be analyzed by an Ecology-certified laboratory.

"If you get the right circumstances - which we had the right circumstances last year, very little rain, high temperatures, that's just conducive for blue-green algae," said Kaputa. "There's a concern that may adversely affect fishing in Roses Lake."

A final Roses Lake Characterization Report is expected in 2027.

Read more about algae bloom from the Washington State Department of Ecology here.

Aerial view of Roses Lake in the foreground. Wapato Lake, upper right, Dry Lake, left, and Lake Chelan in the distance. Photos courtesy: Jeff Conwell.