The EPA and the Corps use the 1987 Corps of Engineers Wetlands Delineation Manual to define wetlands for the Clean Water Act Section 404 permit program. Section 404 requires a permit from the Corps or authorized State for the discharge of dredged or fill material into the waters of the United States, including wetlands. The 1987 manual will remain in use pending review of public comments on the 1991 proposed manual and the ongoing National Academy of Sciences study of wetlands definition.
The 1987 manual organizes environmental characteristics of a potential wetland into three categories: soils, vegetation, and hydrology. The manual contains criteria for each category. With this approach, an area that meets all three criteria is considered a wetland.
