County presents options for Willowmoor project
Published 4:55 pm Thursday, March 19, 2015
King County hosted a public meeting to present updated information project to reconfigure the transition zone between the Sammamish River and Lake Sammamish through Marymoor Park on Saturday at the Redmond Senior Center (RSC).
At the meeting, employees from King County’s Department of Natural Resources and Parks presented three project design alternatives to address existing flood control and habitat issues on the Sammamish River at its outlet in King County’s Marymoor Park near Redmond.
Craig Garric, project manager and a senior engineer for King County, said the outlet is adjacent to the off-leash dog park at Marymoor.
According to a King County press release, the outlet is marked by a shallow concrete weir and a straight, rock-lined channel, 200-feet wide and extending 1,500 feet downstream from the weir. This area is known as “Willowmoor” and is also referred to as the “transition zone,” where the lake becomes the river.
These transition zone features are specifically designed to pass flood flows quickly downstream and to help maintain summer lake levels for recreational use, the release states, while still allowing for upstream fish passage, including salmon returning to the Issaquah Hatchery from their time in saltwater.
The release continues, stating that the transition zone is not sustainable in its current condition and configuration. In order to ensure the transition zone’s capability to pass flood flows, county crews must perform intensive and costly maintenance including mowing, removing sediment and riverside plants.
Garric said reconfiguring the transition zone has three goals. The first is to ensure downstream flood control, flow conveyance and lake level control. The second goal is to enhance habitat conditions in the river channel, associated tributaries and adjacent wetlands for Chinook salmon — which are listed on the Endangered Species Act — and other species. The final goal, Garric said, is to reduce cost complexity and ecological impacts of the transition zone maintenance.
THE OPTIONS
The three reconfiguration alternatives presented on Saturday were the outcome of an ongoing stakeholder advisory committee process that began in 2013 and represents a variety of interests and backgrounds.
The first alternative would be to take no active action and to continue with current maintenance practices.
The second alternative is referred to as the split-channel alternative. This would entail constructing a second panel, parallel to the main channel. Garric said this second channel would be more natural and provide better conditions for wildlife and more conveyance for high flows. This option would improve high lake levels and reduce the number of days lakefront property is affected, he said.
The third alternative presented is more modest, Garric said, and would be to widen the current channel.
Garric said both the second and third alternatives include widening the channel as well as pumping in cold water as the current system does not cool the water “like it used to.” He said warmer waters can be harmful to the adult fish swimming upstream. The second option would pump in cold ground water, while in the third option, warm water would be stored in underground pipes and given time to cool before being pumped back into the waterway. Garric said the third option would have more modest lake improvements compared to the second option, but it would provide more cold water into the system.
Kate Akyuz, the ecologist for the project, said the cold water piece in the two alternatives is unique and would have various benefits.
In the second option, she said, pumping in the cold groundwater, would give the Chinook salmon rest before they continue their journey upstream. In the third option, she said, there would be more substantial cooling impacts on the waterways all the way downstream in Redmond, Woodinville and Bothell.
WILL THEY WORK?
King County Council members Jane Hague and Kathy Lambert attended Saturday’s meeting as the transition zone affects both of their districts, District 6 and District 3, respectively.
“The biggest question is, ‘Is this going to work?’” Hague said about her response — and others’ responses — to the alternatives presented.
Hague said she and Lambert have been working on this issue — which includes docks along Lake Sammamish being submerged underwater or floating away, leading to shoreline degradation — for five years.
“We’ve waited so long (for a solution),” she said.
For Lambert, there was a lot to learn, but she said she plans to followup on the issue to see if they can look at more alternatives in addition to the three presented to the public. She said she needs to know how costs were figured out as well as how people can safely use canoes and kayaks up the weir. Lambert said she would also like to see more coordination across jurisdictions on things such as high water marks, so everyone is on the same page.
Project planning and preliminary design is funded by the King County Flood Control District and the City of Redmond, and will be completed in coordination with King County Parks, the Muckleshoot Indian Tribe, and lakeside property owners.
Funding for final design and construction will be pursued following the completion of this first phase, and will likely include Flood Control District funds combined with federal and state grants.
Project and stakeholder advisory committee information is available on the Willowmoor Floodplain Restoration Project web page at www.kingcounty.gov/rivers or by contacting contact Garric at (206) 477-4694 or craig.garric@kingcounty.gov.
