Rivergate Enhancement Site

Background
This project is a result of a federal consent decree that settled a citizen lawsuit against the Port (Jones vs. Thorne et al.) and several other agencies. The consent decree was signed on January 31, 2001, and it specifies mitigation actions for wetland fills that occurred during the development of the Rivergate Industrial Park over the past 30 years. The consent decree supersedes several earlier mitigation projects.

Mitigation Plan
WapatoThe design results in the restoration and enhancement of approximately 43.7 acres of wetland and riparian habitat for native plants and wildlife in the Rivergate area. The goals of the mitigation are to increase or restore the following wetland functions: water storage capacity, thermoregulation, anadromous fish habitat, amphibian habitat, waterfowl habitat and native plant communities.

The mitigation plan is divided into eight discrete elements:

  1. Construction of an 8-foot-wide asphalt path under the Lombard Street bridge;
  2. North bank, Columbia Slough: removal of fill to native soils and native planting over a width of 150 feet between the Lombard Street bridge and the Columbia Slough rail bridge;
  3. South bank, Columbia Slough: removal of fill to native soils and native planting over a width of 50 feet between the Lombard Street bridge and the Columbia Slough rail bridge;
  4. Leadbetter Peninsula: removal of fill to native soil and native planting over a width of 125 feet around the eastern, southern and western boundaries of the peninsula;
  5. Ramsey Lake visual buffer of native shrubs and trees along a corridor at the top of slope west and north of the Ramsey Lake mitigation area;
  6. Ramsey Lake enhancement: removal of fill to 14 feet NGVD, construction of two meandering swales and native planting;
  7. Culvert removal east of the railroad bridge on the south side of the Columbia Slough;
  8. Construction of a segment of the 40-Mile Loop Trail from the rail bridge east to the Port’s property line, and mitigation for five acres of wetland impacts as a result of trail construction.

Status
All elements have been completed. Final monitoring occurred in 2009, irrigation was removed in 2011 and the site continues to be maintained and invasive species controlled seasonally.

Related Link:
Mitigation Management Program 2008 Annual Report (pdf - 20 MB)