Wetland delineation resources

What is wetland delineation? Wetland delineation establishes the existence (location) and physical limits (size) of a wetland for purposes of federal, state, and local regulations.

Wetland delineation is also an element of a jurisdictional determination. This process identifies which water bodies within a project's boundaries meet the definition of "waters of the United States." For more information on this, see the U.S. Army Corps of Engineers (Corps) Regulatory Guidance Letter 16-01 Jurisdictional Determinations.

Important: The Corps, not applicants or their consultants, determines whether or not a wetland is a "water of the United States," which are regulated under the federal Clean Water Act. If the Corps determines a wetland is not subject to the Clean Water Act, the wetland may still be a "water of the state" and subject to regulation by Ecology and local jurisdictions. (More on wetland regulations)

Use only approved methods and guidance to delineate wetlands on your property.

Resources for conducting a wetland delineation Does a wetland delineation expire? Delineation results and reporting Delineations for difficult situations, including during drought years