Enhancing Transportation Project Delivery

The Watershed Program at WSDOT has developed a method of using watershed characterization to identify the most effective sites for mitigating impacts of highway construction projects.

WSDOT's watershed-based mitigation approach provides more environmental benefits (and is more cost-effective than) “traditional” mitigation options. This approach leads to a more complete understanding of project effects and the condition of surrounding natural resources. Many complex factors are evaluated within a watershed, identifying areas offering the most opportunity to foster overall watershed recovery, including salmonid habitat recovery. When available, existing data sources are used, and extensive use of Geographic Information Systems supports decision-making and data sharing. The process is intended to occur during early stages of project planning where major mitigation challenges are projected for large or multiple transportation projects in a watershed.

A draft Watershed Characterization Methods Document was updated in December, 2004. We are working on an update in 2007.

Four watershed characterization studies present the results of the SR 522 test case, I-405 / North Renton, I-405 / SR-520, and SR 167.

• SR 522 Draft Watershed Characterization Report (pdf, 2.9 mb) February, 2003
• Interstate 405 / North Renton Watershed Characterization Report July, 2004
  Interstate 405 / State Route 520 Watershed Characterization (North Lake Washington, Lake Sammamish) December, 2004
• State Route 167 Watershed Characterization
  (Green / Duwamish Watershed - Puyallup Watershed) May, 2005

For more information, please contact:
Richard Gersib 
(360) 705-7477 or
GersibD@wsdot.wa.gov