The 6-Digit Hydrologic Units, a component of the Watershed Boundary Dataset (WBD), depict the third level hydrologic subdivision of the United States. A 6-digit hydrologic unit may subdivide a 4-digit hydrologic unit or may be equivalent. There are 401 6-digit hydrologic units with an average size of 10,486 square miles (27,159 sq. km.).
View in Map RoomThe 8-Digit Hydrologic Units, a component of the Watershed Boundary Dataset (WBD), depict the fourth level hydrologic subdivision of the United States. A hydrologic unit can accept surface water from upstream drainage areas and may define a drainage area with single or multiple outlet points. An 8-digit hydrologic unit, or sub-basin, is a common management unit for water resource planning and analysis. There are 2,362 8-digit hydrologic units with an average size of 1,783 square miles (4,619 sq. km.).
View in Map RoomThe 10-Digit Hydrologic Units, a component of the Watershed Boundary Dataset (WBD), depict the fifth level hydrologic subdivision of the United States. A hydrologic unit can accept surface water from upstream drainage areas and may define a drainage area with single or multiple outlet points. A 10-digit hydrologic unit, or watershed, divides sub-basins into smaller management areas. There are 18,679 10-digit hydrologic units with an average size of 226 square miles (585 sq. km.).
View in Map RoomThe 12-Digit Hydrologic Units, a component of the Watershed Boundary Dataset (WBD), depict the sixth level hydrologic subdivision of the United States. A hydrologic unit can accept surface water from upstream drainage areas and may define a drainage area with single or multiple outlet points. A 12-digit hydrologic unit, or subwatershed, supports water resource management and planning activities at a localized and site-specific level. There are 101,779 12-digit hydrologic units with an average size of 41 square miles (107 sq. km.).
View in Map RoomDrainage Class, which classifies how quickly water is removed from the soil, has been updated to the October 2019 NRCS SSURGO data release.
View in Map RoomSoil Loss Tolerance, a measure of how much soil can be lost per year without impacting production, has been updated to the October 2019 NRCS SSURGO data release. Note there is a change to the legend used to depict the data in this update.
View in Map RoomSoil Taxonomy Order, which is the broadest classification of soil types, has been updated to the October 2019 NRCS SSURGO data release.
View in Map RoomLand Capability Class, which shows the general suitability of soils for agricultural purposes, has been updated to the October 2019 NRCS SSURGO data release. Note there is a change to the legend used to depict the data in this update.
View in Map RoomThe Soil Boundaries have been updated to the October 2019 NRCS SSURGO data release.
View in Map RoomFlooding Frequency, based on soil characteristics, has been updated to the October 2019 NRCS SSURGO data release. Note there is a change to the legend used to depict the data in this update.
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