Environmental & Ecological Services

Wetland systems are known by many names: bogs, marshes, swamps, ponds, prairie potholes, sloughs, fens, wet meadows, bottomlands and more. Wetlands such as swamps and marshes are often obvious, but some wetlands are not easily recognized, often because they are dry during part of the year or "they just don't look very wet" from the roadside. Wetlands are areas that are covered by water or have waterlogged soils for long periods of time during the growing season. Plants growing in wetlands are capable of living in saturated soil conditions for at least part of the growing season. The U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency define wetlands as the following: Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. So remember, not all wetlands are exactly the same, not all wetlands are "wet", and not all "wet" areas are wetlands. 

 A wetland delineation is a study which identifies the exact boundaries of a wetland.  A wetland delineation must be performed in accordance with the 1987 Corps of Engineers Wetland Delineation Manual and the appropriate Regional Supplement.  A qualified wetland scientist should perform the delineation and prepare a delineation report which conforms with Corps requirements. The 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.

Most local city and county regulatory jurisdictions in Washington State require the use of the 2015 Ecology Wetland Rating System to determine the type of wetland (depressional, riverine, lake-fringe, or slope) and the category (1, 2, 3, or 4). A Category 1 wetland is the highest quality wetland while a Category 4 is the lowest quality.