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Wetland & Habitat Restoration Projects

The port undertakes fish and wildlife habitat projects for a variety of reasons. Sometimes it’s done to compensate for the impacts of development projects. Other times it’s simply to support important conservation objectives. Either way, the port has made significant contributions to regional stewardship initiatives, with an impressive record of accomplishments. 

 Projects Include:
• 178 acres of wetland created or improved
• 1.5 miles of stream improvements
• Restoring 30+ acres of intertidal and saltwater habitat  
• Adding/reintroducing over 34,000 native plants in project areas
• More than half of these projects were voluntary (not related to development) 
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Master Plan - Third Runway Mitigation Summary 
As part of the third runway construction, the U.S. Army Corps of Engineers and Washington Department of Ecology issued permits to impact the 18.37 acres of wetland. In addition, approximately 1,000 feet of Miller Creek fell within the third runway footprint and needed to be relocated.
Although the port was required to minimize impacts in order to obtain environmental permits, the port continued to avoid and minimize impacts after permit approvals and was able to reduce the 18.37 acres of wetland impact to 13.46, a reduction of 4.91 acres. Despite the reduction of impacts, the port remained committed to implementing the full suite of compensatory mitigation, including creating, enhancing, or restoring 112.75 acres of wetland and wetland buffer near the airport.
The airport must be conscious of avoiding hazards to airplanes presented by flying birds. On-site mitigation did not include components for wildlife habitat.  As a result, the port created and enhanced an additional 65.38 acres of wetland and wetland buffer in Auburn, Washington, adjacent to the Green River. In addition to other wildlife function, the Auburn site included four ponds which waterfowl could use to nest and forage for food.
To compensate for impacts to Miller Creek, the port relocated the 980-foot stream section and enhanced another 1.3 miles of Miller Creek that runs next to the runway embankment. Enhancements included removing culverts, bridges, and quarry spalls along the stream banks and adding large woody debris to create more complex fish habitat. Stream mitigation also includes creation of approximately 60-acre feet of floodplain storage to help reduce the affects of urbanization on peak storm flows.
Third Runway Mitigation and Continuous Monitoring 
Total mitigation includes 178 acres of wetland, 1.5 miles of stream, and 60 acre-feet of floodplain mitigation. The port is committed to ensuring the success of its mitigation and has embarked upon a truly unprecedented and rigorous performance monitoring program for a period of 15 years after mitigation construction. Performance monitoring includes observing groundwater in approximately 90 wells to ensure sufficient water is present for wetland function. The port also installed almost 400 vegetation sampling locations at which vegetation survival, cover, and density are estimated. 
The results are used to determine which mitigation is tracking toward ultimate success. In Year 3 after mitigation construction, the port concluded certain mitigation areas required additional action to ensure success. As a result, the port planted an additional 34,000 plants in wetlands and wetland buffers, further augmented the relocated Miller Creek with additional spawning gravel, and removed two additional culverts from the stream corridor.
The port has approximately 11 years of mitigation monitoring remaining.
Aquatic Habitat Restoration - Seaport
Our region's aquatic environment, especially salmon habitat, is one of the Northwest's greatest resources. Around Puget Sound, several wild salmon runs have been protected under the Federal Endangered Species Act. Over 150 years ago, this area was 8.2 square miles of mud flat, marsh, forested wetland and a river channel - an ideal home for fish and wildlife. Protecting, enhancing and, when possible, expanding this remaining habitat is crucial to fish and wildlife survival, especially as our region becomes increasingly urban.
When the Port of Seattle designs and constructs marine facilities; plans are implemented that avoid, minimize, and, when appropriate, compensate for any anticipated effects on aquatic habitat.
As integral parts of major infrastructure projects, the Port of Seattle has:
  • Restored or enhanced over 31 acres of fish and wildlife habitat at 16 sites throughout the Duwamish River, Elliott Bay, Puget Sound, and Lake Washington Ship Canal.
  • Improved light penetration in shallow water areas. These close-to-shore waters are particularly crucial for juvenile salmon, as they allow them to migrate in areas inaccessible to large predators. These young salmon depend on the vegetation in these waters for food and protective cover and these plants need light to grow and thrive. The port has increased light penetration by replacing solid piers with grated structures, removing over water structures and removing or reducing the number of pilings supporting docks. 
  • Removed in-water barriers to migrating juvenile fish including a derelict ferry and sunken marina.
  • Replaced more than 10,000 creosote (petroleum-treated) wooden pilings that contaminated fish habitats with fewer numbers of concrete and steel pilings. New, stronger pilings are installed with greater amounts of spacing, allowing more light to reach these under-pier waters.
  • Cleaned up contaminated sediments. The port continues to lead in cleanup of contaminated sediment in Elliott Bay and the Duwamish Waterway. Dredging in the East Waterway removed more than 100,000 tons of contaminated sediments.
Lower Duwamish River Habitat Restoration Plan (LDRHRP)
In 2009, the Port of Seattle Commission adopted the Lower Duwamish River Habitat Restoration Plan. The plan identifies over 70 acres of habitat restoration and enhancement opportunities on port-owned property on the Lower Duwamish River – from the southern tip of Harbor Island to the turning basin near the south end of Boeing Field. Adoption of the plan was preceded by a robust public involvement process that included shoreline property owners, businesses, Native American tribes, community members and environmental groups. The plan is now being used by the port to guide it’s habitat restoration investments on the Duwamish.
Pier 66 Built with the Environment in Mind
A great example of the port's strategy of incorporating environmental improvements into development projects is Pier 66. When this area was redeveloped as a public use area - complete with restaurants, marina, maritime museum, conference facilities and a cruise ship terminal - concrete pilings replaced creosote-treated wooden ones and the structure was designed to provide more light and migration areas for salmon and other sea life.
Terminal 5 Project Includes Restoration of Aquatic Habitat
Terminal 5 expansion project doubled the cargo terminal area and capacity, which made possible restoration of approximately 1.6 acres of aquatic habitat. This project took place in the upstream portion of the Duwamish Waterway, where habitat important to juvenile salmon was once abundant but had been greatly diminished.

40 acres in 25 years

Creating, improving, and restoring in the Duwamish, Green River, and Elliott Bay watersheds. more

Lower Duwamish River Habitat Restoration Plan 2009
 (10.6MB PDF)

Duwamish tour.JPG
Duwamish River History & Restoration 
(2.32MB PDF)

Seaport Fish and Wildlife Habitat Restoration Projects Map (3 MB PDF)