Wetland Delineations


     The purpose of a wetland delineation is to determine if an area is in fact a wetland, and to delineate the boundary between a wetland and the adjacent non-wetland ground. 

     Three indicators positively identify a wetland:   hydrophytic vegetation, hydric soils, and hydrology.  If all three indicators are present in a study area it willbe  identified as a wetland.  If all three indicators are not present, a study area is not a wetland.  There are few exceptions.

     Wetland scientists at Mark Yinger Associates work as a team to assess study areas.  We use positive, easily defensible methods to determine the presence or non-presence of wetland indicators: hydrophytic vegetation, hydric soils and wetland hydrology.  Our extensive experience in wetland delineation makes our delineations accurate, consistent, and credible to the regulators.

     Our wetland scientists follow the U.S. Army Corps of Engineers Wetland Delineation Manual protocol.  Depending upon the geographic location, west or east of the Cascade Mountains, we use the Mountains and Valleys supplement or the Arid West supplement, developed by the Corps of Engineers to more accurately delineate wetlands that are found in these wetter versus dryer climates.

     The US Fish and Wildlife Service (FWS) List of Plants that Occur in Wetlands is used to determine whether the plants within a study area are wetland plants.

     The Washington State Wetland Rating System is used to assess values and functions of wetlands delineated in Washington.  The Department of State Land's Oregon Rapid Wetland Protocol (ORWAP) is used to assess wetland values and  functions in Oregon.

    Our wetland scientists follow the reporting guidance of the Corps of Engineers, supplemented with the guidance of Washington Department of Ecology or the Oregon Department of State Lands.