Restoring Urban Estuaries: Vigor Shipyards’ Aquatic Habitat Restoration

Estuaries are vital habitats for salmon—providing a safe place away from predators to feed, rest, grow, and transition from freshwater to saltwater in their journey migrating to the ocean. We are continuing to see expanded efforts to restore the habitat that has been lost over the past century of urbanization and industrialization. In the Duwamish, the need for functional estuary habitat is crucial for juvenile Chinook salmon—very few chinook fry migrants are growing and surviving to adulthood due to the lack of intact estuary habitat for rearing.

Image courtesy of Floyd|Snider

Urban watersheds are one of the most challenging places to conduct habitat restoration because they are constrained by the existing industrial uses and limited availability of potential restoration sites. While it is commonly assumed that habitat restoration in urban estuaries is incompatible with an active working waterfront, the ship building company Vigor has created a “pocket estuary” on their active facility on Harbor Island in downtown Seattleand is continuing to conduct industrial work alongside the restored habitat.

Image courtesy of Floyd|Snider

Construction began in May 2021 with the demolition of three piers and World War I-era timber shipways. After removing approximately 5,000 creosote piles and 7,000 cubic yards of contaminated sediments, construction shifted to creating the habitat area. An extensive amount of earthwork was required to construct the off-channel habitat area, using about 65,000 cubic yards of sediments. The state has what is referred to as an “in water work window” to ensure there are no disturbances during the salmon migration season, so all construction had to be conducted between September and February. This element is an added challenge when already working in a tidally influenced area, leading to construction crews often working in the middle of the night.

In March 2023, construction of the site was completed and ready for planting. The constructed site consisted of a sloped embankment creating an intertidal mudflat area, an adjacent marsh, and riparian buffer zone. A berm “island” was created to protect the habitat area from the strong wave action that comes into Puget Sound while also adding more habitat complexity. The design included multiple openings to the off-channel habitat area to encourage fish passage.

Large woody material was placed throughout the site to add habitat complexity and help stabilize the constructed shoreline. Additionally, a barrier consisting of vertical pilings was installed at the opening between the habitat and the Duwamish River to protect the off-channel habitat from any floating debris entering and causing damage. By May 2023, the marsh and riparian buffer areas were planted with native vegetation that tolerate saline conditions—including coniferous and deciduous trees, shrubs, herbaceous plants, and salt marsh plants. In total, a 2.7 acre-area of new aquatic habitat was created in an industrially zoned and ecologically important area.

Vigor’s restoration site is at a unique location where the west waterway enters Elliott Bay, and where restoration actions are not as common as those further upstream in the Duwamish River. With limited existing intertidal habitat along this industrialized area, this new off-channel habitat is key for serving as a refuge site for juvenile salmon at the mouth of the Duwamish River. The new habitat is to be forever protected through deed restrictions on the property, and Vigor will monitor and maintain the constructed habitat and plantings for ten years after the completion of the project to ensure the habitat becomes established.

Scientists with the University of Washington’s Wetland Ecosystem Team and Long Live the Kings are conducting monitoring on fish and insect use at the site to understand how well the habitat is functioning for salmonids and other aquatic life. The goal is for this new refuge to resemble and function like the tidal flats in the Duwamish had before the alteration of the waterway for industrial use, and hopefully we can inspire others to conduct restoration at their working facilities along the Duwamish.