The PORTfolio - A multi-site mitigation bank
The Port of Seattle is establishing a PORTfolio of fish and wildlife habitat mitigation sites through a Multi-Site Wetland Mitigation and Habitat Conservation Bank in the Green-Duwamish Watershed. This watershed has been heavily developed over time, degrading estuarine, riparian, and freshwater wetland environments. The bank will rehabilitate ecological functions and restore priority habitat, while facilitating sustainable growth and development throughout the region. The service area for the mitigation bank includes key sub-watersheds that are critical for local salmon recovery plans – the Lower Green River, the Duwamish Estuary, and marine nearshore areas.
The bank’s first project, Duwamish River People’s Park and Shoreline Habitat Area, will generate more than 500 credits (called “Discounted Service Acre Years,” or DSAYs) which can be used to resolve Natural Resource Damages (NRD) liability. Over 200 competitively priced NRD credits will be available for sale mid-2022. In the near future, the project will also be able to provide conservation credits which can be used to satisfy Endangered Species Act requirements. Revenue generated by the Port through mitigation credit sales will be reinvested in habitat restoration projects in the Green-Duwamish Watershed and Elliot Bay.
The bank will generate additional mitigation credits through habitat restoration and overwater cover removal projects at other sites in the lower watershed, including Terminal 25, Terminal 108, Terminal 107, and Pier 48. Further upstream, the Port will restore 34 acres of freshwater wetlands adjacent to an existing 60-acre mitigation site (the Auburn Wetlands project). By restoring habitat in saltwater, estuarine and freshwater environments, the Port’s multi-site mitigation bank will improve conditions for salmon across several different phases of their life cycle.
The service area for the mitigation bank includes key sub-watersheds that are critical for local salmon recovery plans – the Lower Green River, the Duwamish Estuary, and marine nearshore areas.
Mitigation Credit Release Schedule
NRD credits will be released over a ten-year period based on satisfaction of key project milestones.
| Milestone | Percentage of total credits released |
|---|---|
| Construction complete; "Time-zero" monitoring |
50% |
| Year 1 performance monitoring | 10% |
| Year 3 performance monitoring | 10% |
| Year 5 performance monitoring | 10% |
| Year 7 performance monitoring | 10% |
| Final performance monitoring | 10% |
Mitigation Bank Project Sites
- Duwamish River People’s Park and Shoreline Habitat Area (14 acres)
- Terminal 25 (10 acres)
- The Auburn Wetlands (34 acres)
- Pier 48 (4 acres overwater cover removal)
- Terminal 108 (5 acres)
Learn more
- Read the Multi-Site Wetland Mitigation and Habitat Conservation Bank Prospectus for complete project site details.
