Wetland Delineation

February 11, 2011 - Amendment to state rules changes the wetland delineation manual

Changes to the state wetland delineation manual became effective on March 14, 2011. Read more about the changes

What is wetland delineation?

Wetland delineation establishes the existence (location) and physical limits (size) of a wetland for the 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 Corps' Regulatory Guidance Letter 08-02, Jurisdictional Determinations (issued June 26, 2008, PDF 118 kb).

Remember that the Corps of Engineers (Corps), not applicants or their consultants, determines whether or not a wetland is a "water of the United States" and thus regulated under the federal Clean Water Act (CWA). If the Corps determines that a wetland is not subject to the CWA, the wetland may still be a "water of the State" and subject to regulation by Ecology as well as by local jurisdictions. Ecology regulates wetlands determined by the Corps to be non-jurisdictional due to their isolation from navigable waters.  > More on Isolated Wetlands

How do I delineate wetlands? 

Wetland delineations must be done using the methods outlined in the following:

Wetland delineation should result in three things:

  1. A wetland boundary clearly marked in the field.
  2. A map that clearly identifies data collection points and the boundaries of the delineated wetland. (Topographic and aerial site maps are very helpful.)
  3. A report that explains how the boundary was determined. It should include:

Delineation checklist (PDF) -a checklist of information that should be in your wetland delineation report, as well as a sample report outline.

NOTE:  You may need to hire a qualified wetland professional to help you identify and delineate wetlands (using the manuals listed above) and prepare a delineation report. 
> Hiring a Qualified Wetland Professional (PDF)
-tips to help you find and select a qualified wetland professional.

Questions?

If you have any questions about wetland delineation, contact the regional wetland specialist for your area. 

 

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