George Davis Creek project: Sammamish plans dam removal, culvert replacements and $11.49M construction estimate; construction aimed for 2026 fish window

The City of Sammamish presented a project update Sept. 9 on the George Davis Creek Fish Passage and Stormwater Improvement Project, outlining scope, partners, funding and schedule for design and construction.

Audrey Starce, public works director, and Catherine Hoffman, city stormwater engineer and project manager, told the council the project was designed to restore fish passage for Lake Sammamish species (including kokanee), reduce flooding and maintenance at an existing sedimentation basin, remove an existing dam, replace barrier culverts under transportation corridors and daylight the creek channel where it outlets to the lake.

Scope and technical approach

Project elements shown in staff diagrams include: removal of an upstream dam, graded restoration of the stream channel in the lower reach, replacement of culverts under East Lake Sammamish Parkway and under the East Lake Sammamish Trail (the latter in partnership with King County), removal of an existing bypass pipe and relocation/daylighting of the creek at the outlet to Lake Sammamish. Staff noted historical drainage changes stemming from 20th‑century development and King County’s 1996 high‑flow bypass installation; sedimentation and periodic floods have required frequent basin maintenance.

Cost, funding and partners

Starce said the current construction estimate is approximately $11,490,000 (city estimate after reaching 90% design), with further cost refinement possible as final plans and specifications are completed. The city has applied for and secured several funding commitments and grant sources to offset the cost, including awards or commitments from the Brian Abbott Fish Barrier Removal Board, the Washington State Department of Commerce and King County. Staff said the city is finalizing interlocal agreements and reimbursement provisions with King County and Sammamish Plateau Water and Sewer District so that a single construction contract can be packaged to achieve efficiencies and enable partner reimbursements.

Schedule, permitting and traffic impacts

Design work is concluding in late 2025, permitting is underway and staff plan to advertise the project for construction bids in February 2026. Construction is being scheduled to occur during the 2026 fish‑work window (the staff presentation referenced a July 1 start window) to minimize ecological impacts. Starce and Hoffman warned that culvert replacement under East Lake Sammamish Parkway will require traffic control and likely a prolonged single‑direction traffic closure during the operation that installs the new culvert; final traffic‑control plans will be developed by the selected contractor and shared with the public.

Next steps

Staff said they will return to council with budget adjustments and interlocal agreements this fall and will present communication plans, public‑open‑house and outreach schedules before construction. Council members asked staff about sediment management, staging, and how the work interacts with a separate East Lake Sammamish Parkway road stabilization project; staff said they are coordinating schedules so disruptions are minimized and noted the separate stabilization project is currently on a 2027 construction timeline.

Ending

Starce and Hoffman thanked funding partners and outlined the public notifications and open‑house schedule that will accompany the construction phase.