Amendment to state rules changes the wetland delineation manual

Effective March 14, 2011

State laws require that wetlands protected under the Growth Management Act and the Shoreline Management Act be delineated using a manual that is developed by Ecology and adopted into rules (RCW 36.70A.175; RCW 90.58.380). The Department of Ecology adopted a wetland delineation manual in 1997 (WAC 173-22-080) that was based on the original 1987 Corps of Engineers manual and subsequent Regulatory Guidance Letters.

During the last few years the Army Corps of Engineers has updated and expanded their delineation manual with regional supplements. To maintain consistency between the state and federal delineations of wetlands, Ecology has repealed WAC 173-22-080 (the state delineation manual) and replaced it with a revision of WAC 173-22-035 that states delineations should be done according to the currently approved federal manual and supplements.

Frequently Asked Questions

Do the changes apply only to wetlands in shoreline jurisdiction?

All wetlands in Washington State should be delineated using the federal manual and regional supplements. The Growth Management Act (GMA) (RCW 36.70A.175) states that “wetlands regulated under development regulations adopted pursuant to this chapter shall be delineated in accordance with the manual adopted by the department pursuant to RCW 90.58.380.” RCW 90.58.380 allows the Department of Ecology to adopt rules that incorporate changes to the manual. Therefore, the currently approved federal manual and supplements should be used for delineating wetlands in GMA jurisdiction.

What is Ecology’s statutory authority for making this change?

RCW 90.58.380 allows the Department of Ecology to adopt rules implementing changes to the manual: “If the corps of engineers and the environmental protection agency adopt changes to or a different manual, the department shall consider those changes and may adopt rules implementing those changes.”

Are cities and counties required to amend their Critical Areas Ordinances (CAOs) to reflect these changes?

There is no statutory requirement for local governments to immediately amend their CAO to reflect the recent changes. However, local governments would be required to address the changes the next time they update their plans and regulations comprehensively as required by the GMA at RCW 36.70A.130.

Many local governments have adopted CAOs that specifically require the use of the state delineation manual (Ecology Publication No. 96-94). Others have either included the language “as amended” after the citation or referenced the procedure outlined in WAC 173-22-035. If the local government has not adopted language that specifically authorizes using the most current manual as amended, applicants for wetland permits may be required to submit two sets of data forms: one for the local government according to the old state manual and one for any state and federal permits according to the federal manual and supplements.

Whenever a local government does choose to update the delineation provisions in its CAO, we recommend using the following language:

Identification of wetlands and delineation of their boundaries pursuant to this Chapter shall be done in accordance with the approved federal wetland delineation manual and applicable regional supplements. All areas within the [City or County] meeting the wetland designation criteria in that procedure are hereby designated critical areas and are subject to the provisions of this Chapter.

Hasn’t the federal government been requiring the use of this manual and regional supplements for the last two years?

Yes. Ecology amended its rules to be consistent with Army Corps of Engineers requirements. Starting in 2008, the Corps required the use of its delineation manual and its interim regional supplements. The final regional supplements were released in 2010. During the interim period, Ecology accepted data forms from both the federal and state delineation manuals.

If applicants have to use two different manuals, will this result in two different delineated boundaries?

Based on our experience, it is very rare that wetland boundaries differ when applying the state manual and the new federal manual with applicable supplements. When applied correctly, the two manuals should result in the same boundary. When this is not the case, the applicant should consult with Corps or Ecology wetlands specialists to help determine whether the difference is appropriate.


If you have any questions about the state rule changes, contact:

Lauren Driscoll


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