Wetland Mitigation

Generally, mitigation means countering the negative environmental impacts that developing the land can have on wetlands, rivers, streams, lakes, and other deep-water habitats. Wetland compensatory mitigation is the stage of the mitigation sequence, where impacts to wetland functions are offset through creation, restoration, enhancement, or preservation of other wetlands.  

Updating our wetland mitigation guidance

We’re working with the Environmental Protection Agency (EPA) and the US Army Corps of Engineers (Corps) to update our interagency wetland mitigation guidance.

Our current interagency wetland mitigation guidance was published in 2006. Since then, there have been changes in the world of wetland mitigation. A federal mitigation rule was issued in 2008, and Ecology has 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 In addition, many of the references and web links in the documents are no longer current. Our goal is to integrate these new tools and policy changes into a unified document that will provide clear guidance on wetland mitigation goals and requirements. We plan to have the updated guidance by May 2018.

You can stay up to date on this process by signing up for email updates through our wetlands listserv.

More information

Avoidance and Minimization - Information to assist development project applicants in understanding the requirements for wetland impact avoidance and minimization during development projects

Interagency Wetland Mitigation Guidance - Guidance on wetland mitigation from Ecology, the Corps' Seattle District, and the EPA's Region 10.  The agencies provide this guidance to help the regulated community comply with environmental laws and policies and to improve the quality and effectiveness of mitigation in Washington.

Mitigation Resources - A comprehensive list of mitigation resources.

Mitigation Options - Includes information on Wetland Mitigation Banking, In-Lieu Fee Mitigation, Off-site mitigation, and Advance mitigation.

Wetland Mitigation Compliance - The purpose of compliance is to ensure that permittees meet the terms and conditions of their permits, including successful implementation of any required mitigation plan. Regulatory agencies strive to work collaboratively with permittees to ensure that the mitigation plan is implemented successfully and complies with the conditions of the permit.

Wetland Mitigation Evaluation Study - A two-phase study from 1999-2002 that evaluated permit compliance and ecological success of mitigation projects in Washington State.

Mitigation That Works Initiative - Ecology’s goal is to improve mitigation from 50 to 100 percent environmental success – and do it in a way that provides more predictability for permit applicants. We call this “Mitigation that Works.” A Mitigation That Works Forum published a report in December 2008. The report details the Forum's recommendations on how to improve all aspects of aquatic resources mitigation.