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- Hydric Rating by Map Unit—Hennepin County,Minnesota 500 Hunter Pass <br /> Description <br /> This rating indicates the percentage of map units that meets the criteria for hydric <br /> soils. Map units are composed of one or more map unit components or soil types, <br /> each of which is rated as hydric soil or not hydric. Map units that are made up <br /> dominantly of hydric soils may have small areas of minor nonhydric components in <br /> the higher positions on the landform, and map units that are made up dominantly <br /> of nonhydric soils may have small areas of minor hydric components in the lower <br /> positions on the landform. Each map unit is rated based on its respective <br /> components and the percentage of each component within the map unit. <br /> The thematic map is color coded based on the composition of hydric components. <br /> The five color classes are separated as 100 percent hydric components, 66 to 99 <br /> percent hydric components, 33 to 65 percent hydric components, 1 to 32 percent <br /> hydric components, and less than one percent hydric components. <br /> In Web Soil Survey, the Summary by Map Unit table that is displayed below the <br /> map pane contains a column named'Rating'.In this column the percentage of each <br /> map unit that is classified as hydric is displayed. <br /> Hydric soils are defined by the National Technical Committee for Hydric Soils <br /> (NTCHS) as soils that formed under conditions of saturation, flooding, or ponding <br /> long enough during the growing season to develop anaerobic conditions in the <br /> upper part(Federal Register, 1994).Under natural conditions,these soils are either <br /> saturated or inundated long enough during the growing season to support the <br /> growth and reproduction of hydrophytic vegetation. <br /> The NTCHS definition identifies general soil properties that are associated with <br /> wetness. In order to determine whether a specific soil is a hydric soil or nonhydric <br /> soil, however, more specific information, such as information about the depth and <br /> duration of the water table, is needed. Thus, criteria that identify those estimated <br /> soil properties unique to hydric soils have been established (Federal Register, <br /> 2002). These criteria are used to identify map unit components that normally are <br /> associated with wetlands.The criteria used are selected estimated soil properties <br /> that are described in"Soil Taxonomy" (Soil Survey Staff, 1999) and"Keys to Soil <br /> Taxonomy"(Soil Survey Staff, 2006)and in the"Soil Survey Manual"(Soil Survey <br /> Division Staff, 1993). <br /> If soils are wet enough for a long enough period of time to be considered hydric, <br /> they should exhibit certain properties that can be easily observed in the field.These <br /> visible properties are indicators of hydric soils. The indicators used to make onsite <br /> determinations of hydric soils are specified in"Field Indicators of Hydric Soils in the <br /> United States"(Hurt and Vasilas, 2006). <br /> References: <br /> Federal Register. July 13, 1994. Changes in hydric soils of the United States. <br /> Federal Register. September 18, 2002. Hydric soils of the United States. <br /> Hurt, G.W., and L.M. Vasilas, editors.Version 6.0, 2006. Field indicators of hydric <br /> soils in the United States. <br /> uSpq Natural Resources Web Soil Survey 12/10/2015 <br /> � Conservation Service National Cooperative Soil Survey Page 4 of 5 <br />