Cochran Springs Creek Restoration

City of Kirkland, Kilroy Realty (http://www.kilroyrealty.com/)
Kirkland, WA

An office complex in Kirkland no longer faces frequent flooding of its garages, thanks to stormwater solutions and an urban stream restoration designed and managed by The Watershed Company.

Hydraulic and hydrologic analysis determined that reduced flow capacity was the primary cause of the flooding. Baseline studies documented existing fish distribution and use.  Biologists found that fish passage through Cochran Springs Creek was inhibited by a lack of channel definition over a large sheet-flow area where water was too shallow for fish. Engineering design included an excavated sediment trap and regrading of 800 feet of Cochran Springs Creek. Stream restoration provided fish passage through excavation of a new channel, pool/riffle definition with log and boulder placement, woody cover and native plantings.

The urban restoration project was a public-private partnership between Kilroy Realty and the City of Kirkland.

Watch a video about the restoration on our YouTube channel.

Placed logs in a new stream channel

A restored channel for Cochran Springs Creek allows fish passage and prevents flooding.

Aerial of newly excavated channel

Looking down on the restored channel a month after completion

Logs in restored stream channel of Cochran Springs Creek

After restoration, 800 feet of channel was regraded and enhanced.

Before restoration, the area between two buildings was a sheet-flow that prevented fish passage.

Moving a root wad into position in the new channel

Heavy man-power was needed to position large woody debris in the restored stream channel.

Before restoration, the creek flooded the parking garage.

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