Hamm Creek Habitat Restoration Project
Location: Duwamish River, Seattle, Washington
Funding Source: City of Seattle/Metro Settlement
Design Objectives:
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Recreate one acre of intertidal estuarine marsh habitat from upland fill along
the Duwamish Waterway.
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Create two acres of freshwater marsh.
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Create 1,900 feet of new productive riparian stream bed.
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Establish a "fish-passable” connection to the Duwamish River.
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Restore access to Hamm Creek for salmonid spawning.
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Protect in perpetuity the site for natural resources.
Site Summary
The restoration site is a roughly "V” shaped 6.2-acre parcel of land in the vicinity of Turning Basin No. 3 of the Duwamish Waterway. It is within the 21.5-acre Duwamish Substation property owned by Seattle City Light. Historically, Hamm Creek meandered through an intertidal marsh at the site and flowed into the Duwamish River. From the early 1950’s through 1971 the site was used as a dredged material stockpiling area. Consequently, Hamm Creek was "placed” in a ditch and routed into a culvert with an outfall into the Duwamish River accessible to fish only at higher tides.
Restoration Activities
Together with the U.S. Army Corps of Engineers under Section 1135 funding, King County created 2,300 feet of new productive riparian stream bed and channel for Hamm Creek along the northern and western portions of the site. The Elliott Bay/Duwamish Restoration Program purchased a conservation easement to cover all restoration construction activities and has been responsible for the design and monitoring of a one- acre estuarine marsh with fish-passable connection to the Duwamish Waterway. The enhanced freshwater Hamm Creek channel features meanders, fish pools, and large woody debris. Native trees and shrubs forming a riparian buffer are to be planted on the upper slopes of the bank. The intertidal habitat was planted with native estuarine marsh vegetation in spring 2000.
Construction started in July 1999 and the project was completed in the year
2000. See design map.
Monitoring for intertidal habitat success is being conducted under the Elliott Bay/Duwamish Restoration Program's restoration monitoring plan, with the last monitoring scheduled for 2015.
Stream monitoring will be conducted by other agencies.
