Project Overview

Graphic view of vicinity of the Springbrook Bank site showing the urban setting. The five units of the bank are colored green and blue.

WSDOT and the City of Renton are jointly developing the 130-acre Springbrook Creek Wetland and Habitat Mitigation Bank (Springbrook Bank) in King County. Under a partnership agreement between Renton and WSDOT, the city has contributed the land where the bank will be constructed and WSDOT has funded design and will fund construction beginning in 2007. Over the next ten years Springbrook Bank will provide up to 45 mitigation credits that will be divided equally between WSDOT and Renton. 

The Mitigation Bank Instrument  (pdf 6.15 mb) for the Springbrook Bank was completed in September 2006. Springbrook Bank is WSDOT’s third certified mitigation bank, the first urban mitigation bank in Washington State, and the first such partnership between a state agency and local government.

Expected Use

WSDOT will use its credits at Springbrook Bank to provide mitigation for planned transportation projects—primarily Interstate 405 projects in Tukwila and Renton that are within the service area of the bank. The City of Renton will use its bank credits to as mitigation for anticipated projects within city limits.

Ecological Goals

View looking southeast from west side of Springbrook Creek. Riparian enhancements and trail planned along the creek in this urban area.

The goals of the bank are to:

• Improve wetland and riparian habitat
• Increase wildlife habitat functions
• Improve water quality and flood storage
• Provide educational opportunities for the local community.

When construction is complete the Springbrook Bank project will have created approximately 18 acres of new wetland area, rehabilitated or enhanced approximately 85 acres of existing wetlands, and increased the hydrologic connectivity between Springbrook Creek and adjacent wetlands by breaching manmade levees. The bank will also include an elevated boardwalk to provide environmental education opportunities for local residents and complete a gap in the King County regional trail system.