Interagency wetland mitigation guidance

Wetland Mitigation in Washington State is a two-part interagency document providing guidance on wetland mitigation. You can access the current mitigation guidance documents (Parts 1 and 2) below.

2021 update to Part 1 now available

We worked with the Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (Corps) to update Part 1 of our interagency wetland mitigation guidance that was originally published in 2006.

Since 2006, there have been changes in the world of wetland mitigation. A federal mitigation rule was issued in 2008, and we've developed several tools for incorporating a watershed approach, and calculating mitigation gains and wetland losses. In addition, many of the references and web links in the document were no longer current. We integrated these new tools and policy changes into a unified document to provide clear guidance on wetland mitigation goals and requirements. 

A draft update was released for public comment from Oct. 1 through Nov. 30th, 2020. 

Part 1 — Agency policies and guidance

Part 1 provides a brief background on wetlands, an overview of the factors that are considered in the agencies' permitting decisions, and detailed guidance on the agencies' policies on wetland mitigation, particularly compensatory mitigation.

Part 2 — Developing mitigation plans

Part 2 provides technical information on preparing plans for compensatory mitigation.

Monitoring guidance

The U.S. Army Corps of Engineers (Corps) issued a regulatory guidance letter to clarify monitoring requirements for compensatory mitigation projects. The Corps' Seattle District has incorporated the most recent guidance letter (RGL 08-03) into their monitoring requirements for compensatory mitigation projects.

Other mitigation resources

We've published a number of guidance documents designed to improve mitigation. For example, in 2009 and 2010, we published guidance on selecting wetland mitigation sites using a watershed approach for both Eastern and Western Washington. This and all other mitigation guidance is available on our Wetland Mitigation Resources page.

We announce when new guidance is available through our wetlands information email list.