Description: The US Department of Agriculture’s (USDA) Natural Resources Conservation Service (NRCS) develops soil surveys that include maps of soils and related reports. Extensive field work is done to complete the mapping and document findings. The maps consist of outlined areas called map units. These are areas with generally similar soils, or a similar mix of soil types that can be consistently identified across the landscape. When more than one named soil occurs in a map unit, each soil is called a component of the map unit. Each component makes up a certain percentage of the map unit. Two subsets of the soils dataset are helpful in predicting the presence of wetlands and are included in the SWI.<br>Some soils naturally retain water longer than others, especially when they occur on certain parts of the landscape, such as depressions. These soils often exhibit characteristics (e.g. routinely flooded) that meet the definition of, and they are designated as “hydric soils.” (NRCS Hydric Soils List Criteria https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/use/hydric/?cid=nrcs142p2_053959) Because of these characteristics hydric soils are often found on the landscape where wetlands occur.<br>The SWI shows soil map units that are comprised of predominantly (greater than 50%) hydric soil components. This means that a user can expect more than half of that soil map unit to include soil components that have been designated as hydric. These map units indicate places across the landscape with a higher likelihood for wetland occurrence. Displaying predominantly hydric soil map units in the SWI is especially helpful in recognizing potential wetland areas in places where only the NWI wetland mapping is available.<br><br><a href="https://www.oregon.gov/dsl/WW/Documents/DSLSWILayerLimitationsFinal.pdf" target="_blank">DSL SWI Disclaimer and Layer Descriptions and Limitations</a>