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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 Washington State Wetland Identification and Delineation Manual (Chapter 173.22.080 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.
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.
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.
| Download separate sections (recommended for slower connection speeds) | |
| Eastern Washington Volume | Western Washington Volume |
Annotated versions of the eastern and western Washington manuals are now also available. The annotations attempt to respond to the numerous questions we have received about different aspects of the rating system since it was published. Comments are included in "balloons" next to the appropriate text. The original documents, Ecology publications #04-06-15 and #04-06-025, have not been changed, and the annotated versions still retain the same publication number.
Download annotated version of Western Washington Wetland Rating System (3.5 mb. pdf)
Download annotated version of Eastern Washington Wetland Rating System (2.6 mb. pdf)
The rating forms for both eastern and western Washington were updated in June and July 2006 to increase accuracy and reproducibility among users. They can be downloaded below.
Western Washington (Version 2) (144 k., pdf)
Eastern Washington (Version 2) (136 k., pdf)
Focus SheetFocus 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.
Click to view the list of those who have attended the training for Western Washington (pdf)
Click to view the list of those who have attended the training for Eastern Washington (pdf)
Need more information? Contact Tom Hruby (360.407.7274).
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.
