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Project description

Chinook Wind Mitigation Project is located on a 5.83-acre property at river mile 6.7 on the north bank of the Duwamish River in the City of Tukwila. Prior to King County acquisition, the property was home to a run-down hotel and parking lot. Preliminary design began in early 2018 to create up to 4 acres of new estuarine wetland, aquatic and riparian habitat area in the space once occupied by the hotel and parking lot. The design will include off-channel aquatic and intertidal mud flat habitat, as well as low and high marsh, and riparian habitat. Chinook Wind is downstream from the City of Tukwila’s Duwamish Gardens Shoreline Restoration project and together the sites provide critical, rare off-channel and shallow-water edge habitat for Chinook and other salmon.

Background

97% of the estuarine wetland habitat in the Duwamish River has been lost in the last 150 years (WRIA 9 Salmon Habitat Plan 2005). Land along the densely-developed Duwamish River is expensive and seldom available for purchase. The Chinook Wind site represented a rare opportunity to acquire and permanently protect a large area in the “transition zone.” The project will create significant and valuable off-channel habitat where juvenile salmon can reside while adjusting from fresh water to salt water as they feed and grow.

King County purchased the Chinook Wind property in August 2015 and hired a contractor to remove buildings and impervious surfaces, including asbestos and other hazardous materials, from the site. Impervious surface removal was complete as of May 2016. Preliminary design of the habitat creation project began in early 2018. Key decisions related to site selection and mitigation project design are subject to review and approval by an Interagency Review Team made up of representatives from regulatory agencies, tribes and affected governments.

 

Point of contact

Primary point of contact (project manager) -- Laird O'Rollins
Project sponsor -- Megan Webb

Vicinity maps

ChinookWind_LocatorMap  

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ChinookWind_NearbyPublicLandsMap

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Site history

Aerial imagery of vicinity prior to King County demolition work:
ChinookWind_AerialImageOfNeighborhoodPreDemolition

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Aerial imagery of site prior to King County demolition work:
ChinookWind_AerialImageOfSitePreDemolition

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Aerial imagery of site after King County demolition work:
ChinookWind_AerialImageOfSitePostDemolition

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On-the-ground photographs from demolition:

Photographs 1 & 2 : Demolition of hotel building (March 24th, 2016 then March 28th, 2016) JPEG (182 KB)


 

Photograph 3: Demolition complete, impervious surfaces removed, hydro seed installed (view northeastward, approx. 270° panoramic photo; May 9, 2016) JPEG (244 KB)
ChinookWind_FieldPhoto3_PanoramaOfHydroSeedPostDemo

 

Diagram of proposed project

King County Mitigation Reserves Program proposes a preliminary design that provides sheltered off-channel habitat surrounded by mudflat, low marsh, high marsh and riparian habitats. The Chinook Wind Mitigation Project offers an extraordinary opportunity to provide a rare resource that is immensely important for ESA-listed juvenile Chinook. Persistently inundated aquatic habitat represent extremely limited and critically important habitat for ESA-listed juvenile Chinook. Once common in the Duwamish, marshes are now extremely rare. When adjacent to mudflat and aquatic habitat, marshes provide valuable sources of food for juvenile Chinook. 

ChinookWind_ProposedProjectDiagram
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Illustration of Duwamish estuary tidal cycle at Chinook Wind after completion of proposed project:

ChinookWind_TidalCycleAnimation

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Project schedule

Chinook Wind Mitigation Project schedule overview
Acquisition & Impervious Surface Removal                

Property Acquired

August 2015

Contractor removed existing buildings and impervious surfaces  

May 2016
Restoration of Shoreline  

Stakeholder outreach 

May 2018

Alternatives analysis complete 

August 2018

30% design plans complete

January 2019

SEPA/Public Comment Period

Early 2019

60% design plans complete

June 2019

100% design plans complete

February 2020

Notice to Proceed

April 2020

Implementation

April 2020 - April 2021

Monitoring

April 2021 - April 2031

 

Project documents

[None currently]

 

For more information about King County’s Mitigation Reserves Program, please contact Megan Webb, Program Manager (in the Water & Land Resources Division’s Rural and Regional Services Section).