This major road and bridge project involved design of a new 900-foot bridge across the combined Issaquah Creek/North Fork Issaquah Creek floodplain and replacement of a 30-foot-long bridge over North Fork Issaquah Creek.
The project included relocating 500 feet of North Fork Issaquah Creek, a locally important salmon stream, in a manner that reconnected the creek to its floodplain while providing improved habitat and reducing flood risks for downtown Issaquah.
ESA provided bridge hydraulics, channel realignment, fish passage design, floodplain analysis, mitigation design, landscape architecture, and all environmental permitting. Other design elements included a 0.9-acre wetland mitigation area critical to offsetting the floodplain impacts of the bridge and extensive native plantings. To provide fish habitat and support an efficient permitting process, ESA’s fish-passable design incorporated large wood habitat structures, bioengineered bank stabilization, floodplain benches, streambed sediments, and native plantings.
ESA prepared plans, specifications, and cost estimates as well as city, state, and federal permit applications. ESA also provided additional services during construction, which was completed in late 2018.