Wetland Function Assessment Project

The Wetlands Function Assessment Project was a statewide effort in 1996-2001 to develop relatively rapid, scientifically acceptable methods of assessing how well wetlands perform functions such as improving water quality, reducing floods, and providing wildlife habitat. The methods were developed for different wetland types in Washington State.

The project was coordinated by Ecology with funds from the U.S. Environmental Protection Agency. 

Washington State Wetland Function Assessment Methods (WFAM)

Methods for Assessing Wetland Functions, commonly called the Washington State Wetland Function Assessment Methods (WFAM), are a collection of assessment methods that were developed by an interdisciplinary teams of experts. The assessments provide a score for the degree to which several functions (up to 15) are performed by a wetland. The methods are based on the hydrogeomorphic (HGM) classification for wetlands, which categorizes wetlands into groups that function in similar ways (based on the geomorphic and hydrologic characteristics). The highest categories (i.e., classes) for wetlands in a region are defined nationally. Subclasses for each of these classes are defined regionally by experts within that area. In Washington, regions were created to reflect the differences in wetland functions, or differences in how functions are performed.

HGM Classes

  • Riverine
  • Depressional
  • Slope
  • Lacustrine Fringe
  • Estuarine Fringe
  • Flats (Mineral and Organic) 

Regions in Washington

  • Montane

  • Lowlands of Western Washington
  • Columbia Basin
  • Lowlands of Eastern Washington

Methods for assessing wetland functions were completed for HGM classes/subclasses in two regions in Washington: Lowlands of Western Washington (riverine and depressional wetlands) and the Columbia Basin (depressional wetlands). The methods can be downloaded below.

Methods for the Columbia Basin and the Lowlands of Washington

Current Applicability of the Methods

Ecology highly recommends that those who apply the methods only do so after attending a five-day training session. Training is important to properly interpret and apply the methods, especially when collecting data in the field.  Training is also important so results are accurate, consistent, and reproducible. Ecology has been unable to offer training on the methods in over ten years and does not have plans to offer training in the foreseeable future, therefore Ecology can no longer support its use to assess functions of wetlands. 

The documents are provided here for historical reference to those wishing to explore the scientific basis for the wetland rating system, which is the current tool for gathering general information on functions provided by wetlands. 

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