Washington State Wetland Rating Systems

Draft Updates to the Washington State Wetland Rating Systems

Ecology is in the process of updating Washington State Wetland Rating Systems.  Ecology accepted public comments on the draft updates to the rating systems through March 31, 2014.  Staff are currently reviewing the comments received. We expect a final version incorporating your comments will be ready in May.

 > Learn more about the draft updates

The wetlands in Washington State differ widely in their functions and values. Some wetland types are common, while others are rare. Some are heavily disturbed while others are still relatively undisturbed. All, however, provide some functions and resources that are valued. These may be ecological, economic, recreational, or aesthetic. Managers, planners, and citizens need tools to understand the resource value of individual wetlands in order to protect them effectively.

The wetland rating systems were designed to differentiate between wetlands in western and eastern Washington.  They categorize wetlands into four categories based on their sensitivity to disturbance, their rarity, our ability to replace them, and the functions they provide. The rating system, however, does not replace a full assessment of wetland functions that may be necessary to plan and monitor a project of compensatory mitigation.

The “rating” categories are intended to be used as the basis for developing standards for protecting and managing the wetlands to reduce further loss of their value as a resource. Some decisions that can be made based on the rating include the width of buffers needed to protect the wetland from adjacent development, the ratios needed to compensate for impacts to the wetland, and permitted uses in the wetland. The Department of Ecology has developed recommendations for such protective standards and these are available in volume 2 of the "Best Available Science" report.

The rating systems are primarily intended for use with vegetated, freshwater, wetlands as identified using the using the federal wetland delineation manual (PDF) and applicable regional supplements (Chapter 173-22-035 WAC). It also categorizes estuarine wetlands but does not characterize their functions. The rating systems, however, do not characterize streambeds, riparian areas, and other valuable aquatic resources.

Current Annotated Versions of the Rating Systems

Eastern Washington (Publication #0406015) - The Eastern Washington Rating System was revised August 2004.  This revision replaces the 1st edition of the rating system for eastern WA published in 1991. Annotations to address frequently asked questions were added to this version in March 2007.

Western Washington (Publication #0406025) - The Western Washington Rating System was revised August 2004.  This revision replaces the second edition of the rating system for western Washington published in 1993. Annotations to address frequently asked questions were added to this version in August 2006.

Updated Rating Forms

The rating forms for both eastern and western Washington were updated in October 2008 to include the new definitions for priority habitats in Question H2.3. The updated forms can be downloaded below. The last link is to the new definitions that have been released by the Washington Department of Fish and Wildlife. The definitions should be consulted to answer questions H2.3 correctly (the descriptions on the rating forms do not describe the priority habitats adequately).

NOTE: The annotated versions of the eastern and western Washington rating systems and the updates of both the eastern and western rating forms DO NOT CHANGE ANY SCORES OR RATINGS that would result from using the original manuals. The annotated manual and updated forms provide clarifications only.

Focus Sheet

Focus on: Using the Wetland Rating System in Compensatory Mitigation - Explains constraints inherent in the Washington State
Wetland Rating Systems when used for estimating changes in functions.


The Department of Ecology provides training for those wanting to use the wetland rating systems. Scheduled classes can be found at our Coastal Training Web site.

Need more information? Contact Tom Hruby (360-407-7274)