Lake Sammamish levels raise concerns among shoreline residents
March 30, 2011
By Warren Kagarise
NEW — 3 p.m. March 30, 2011
Leaders said King County is removing invasive aquatic plants and enacting other steps along Lake Sammamish in order to address high water levels along the shoreline.
County Executive Dow Constantine said the county plans a series of steps to reduce the seasonal flooding along the lake.
“We are taking immediate action to provide relief for lakeside residents who have to deal with high lake levels — particularly during the wettest months of the year,” he said in a statement released Wednesday.
The outlet from Lake Sammamish into the Sammamish River at county-run Marymoor Park is marked by a shallow, fixed-concrete spillway and a section of channel downstream from the weir. The area, called the transition zone, marks the shift from lake to river.
The area is designed to pass flood flows quickly downstream. In addition, the features help hold water in the lake in summer for recreational uses and allow for upstream passage of fish, including salmon returning to the Issaquah Salmon Hatchery.
In order to high water level in Lake Sammamish, the county is evaluating the potential for removal of accumulated sediment in the transition zone. The county is also working alongside the Redmond municipal government on a proposed project to modify the transition zone to create more capacity in the river.
Constantine also said the county is quadrupling the frequency of mowing in the transition zone. The dense vegetation impedes flows out of the lake.
Crews plan to mow the area each year, and as late in the season as possible, in order to reduce the vegetation heading into the wettest time of the year.
The county also plans to yank aquatic weeds in the transition zone through the King County Noxious Weed Program.
“This proposed action plan will protect private property, address salmon habitat needs, and also meet the requirements of our maintenance agreement with the Army Corps of Engineers,” County Councilwoman Kathy Lambert, the Issaquah and Sammamish representative, said in a statement. “Bringing in partners such as the city of Redmond will help to ensure the success of our long-term plan for the weir and the water levels on the lake.”