The Duwamish River restoration projects have created crucial habitats for birds, fish, and invertebrates in an otherwise industrial landscape.
Three restoration sites along Seattle’s industrialized Duwamish River are showing signs of recovery, though human activity continues to threaten wildlife populations. The Duwamish River restoration projects aim to rebuild natural habitats that support important species of birds and fish in this heavily developed waterway.
The Port of Seattle and other commercial facilities have caused significant damage to the Duwamish Estuary over many years. The restoration work focuses on three locations: the Turning Basin, the General Services Administration (GSA) site, and Terminal 105.
Each Duwamish River restoration project followed a similar approach. Workers first removed debris, then reshaped the shoreline to restore natural water levels, and finally replanted native vegetation along the riverbanks.
At the GSA site, teams removed rock barriers and an old wharf structure. They built a “sediment bench” at water level to create feeding areas for young salmon. They also planted native vegetation on higher ground.
The Terminal 105 (T-105) site previously contained an abandoned street end and a large pipe draining a small, degraded wetland. Restoration crews removed debris and replaced the pipe with a channel that allowed natural tidal flow to return to the area.
The Turning Basin project created planted areas with native vegetation along the upper shoreline. Workers added native sedge (Carex lyngbyei) and rush (Scirpus maritima) plants in the shallow water zones.
These Duwamish River restoration efforts received funding through a combination of federal grants, municipal allocations, and contributions from environmental organizations. While the exact budget figures remain unknown, similar urban river restoration projects typically cost between $500,000 and several million dollars, depending on site complexity and contamination levels.
The funding strategy for the Duwamish River restoration emphasized cost-effective approaches that could achieve meaningful ecological improvements with limited resources. This is why the three sites were specifically chosen for their potential to show marked habitat improvements with restricted funding.
Scientists monitoring these sites have found encouraging results. Small invertebrate animals, which form the base of the food chain, are returning in numbers similar to those in natural reference sites. Researchers have counted between 11 and 29 different types of these tiny creatures across the restored areas.
T-105 has developed particularly impressive populations of small crustaceans, such as Corophium and Eogammarus, despite being located at a higher elevation than the reference sites. Scientists did not expect this level of recovery, given the site’s position.
The restored sandflats at T-105 now host dense populations of a polychaete worm, Manayunkia aesturina, and a small crustacean, Huntemannia jadensis. Young flatfish feed on these small animals.
The Turning Basin’s sandy areas have attracted high numbers of ceratopogonid fly larvae for two consecutive years. Another small crustacean, Mesochra rapiens, important to the food chain, was abundant in 1997.
Harpacticus, a tiny animal that young salmon feed on, was found only at the GSA intertidal bench and another created bench in the lower waterway.
Bird life has also shown positive responses to the Duwamish River restoration. During nine seasons of monitoring, scientists have counted 87 bird species on the Duwamish waterway. Spring months brought the highest numbers, with 58 species in spring 1997 and 48 species in spring 1998.
The Turning Basin site consistently showed the greatest diversity of shorebirds throughout the year. Red-winged blackbirds successfully raised young in the cattail marshes, and American goldfinches showed territorial behaviour and raised their young around the protected plant areas.
Birds used each site differently. Many birds passed through T-105, while active feeding and resting happened mostly at Kellogg Island (a reference site) and the Turning Basin restoration site.
Community involvement has been an important component of the Duwamish River restoration projects. Local volunteer groups regularly participate in planting events, debris removal, and invasive species management. These community stewards help maintain the restored areas while building public awareness about the ecological importance of the river.
School groups from nearby neighbourhoods visit the sites for environmental education opportunities, learning firsthand about ecosystem recovery and the challenges of urban river restoration. This community participation helps ensure long-term support for the Duwamish River restoration efforts.
Plant life varies across the restored sites. The GSA site has developed an understory dominated by Scirpus marina, Cotula coronopifolia, and Lilaeopsis species. Every test plot contained understory species, with 3 to 6 species in each area.
At the Kellogg Island reference site, the main plants include Carex lyngbyei, Potentilla palustris, Plantago maritima, and Distichlis spicata. Natural recruitment of Carex has begun at this site.
T-105 shows heavy recruitment of Atriplex patula on both sides of the channel. Researchers found this plant in every test plot. Various other native species are beginning to establish in smaller numbers.
The Turning Basin has developed the most diverse plant community, with 16 species observed in the sampled area. Between three and eight plant species were found in each test plot. This diversity appears in areas protected from goose grazing, which has been a challenge for plant establishment.
Despite these positive signs, the Duwamish River restoration projects face ongoing challenges. The Turning Basin shows the most promise for bird habitat among the three sites. Its relative isolation had already made it attractive to birds before restoration began. Two additional restoration projects planned next to this site will create more habitat and connections with existing natural areas.
T-105, however, has shown a decline in bird numbers and diversity due to increasing human activity. The construction of a rendering plant west of T-105 removed trees and brush where 15-20 white-crowned sparrows had previously lived. Since then, no more than one male white-crowned sparrow has been seen at the site.
Killdeer nested in shrub roses above the slough at T-105 in 1997, but showed no nesting activity the following year. Human visitors, often with dogs, were present during almost every scientific monitoring visit in 1998. This disturbance, combined with habitat loss, may permanently reduce the number of birds at the site.
Plant growth faces different challenges across the sites. In upstream areas, rock barriers and goose grazing limit vegetation spread. Downstream areas are affected by strong wave action and damage from floating debris. The availability of seeds doesn’t appear to be a limiting factor, as many species grow successfully when protected from grazing.
The Duwamish River restoration projects share similarities with other urban river recovery efforts across the country. The Los Angeles River restoration has faced comparable challenges with industrial contamination and urban development pressures. Like the Duwamish projects, the LA River efforts focus on creating habitat “patches” that can support wildlife in an otherwise developed landscape.
The Bronx River restoration in New York has shown how even small habitat improvements can attract a surprising diversity of wildlife to urban waterways. Similar to the Duwamish River restoration, the Bronx project has relied heavily on community involvement to maintain restored areas.
Chicago’s restoration of portions of the Chicago River system demonstrates the necessity of a long-term commitment for success. After nearly three decades of work, water quality has improved enough to support over 70 fish species, providing hope that continued effort on the Duwamish can yield similar results over time.
See also: Historic Klamath River Dam Removal Project
These restoration projects demonstrate both the possibilities and challenges of urban habitat recovery. While natural processes are returning to these damaged sites along the Duwamish River, human activity continues to threaten their long-term success. However, with continued community support and ecological monitoring, the Duwamish River restoration projects provide valuable testing grounds for urban ecological recovery techniques.
