This map and accompanying table show Hydrologic Unites that are basically hydrographic in nature. The Cataloging Unites shown supplant the Cataloging Units previously depicted n the 1974 State Hydrologic Unit Map. The boundaries as shown have been adapted from the 1974 State Hydrologic Unit Map, "The Catalog of Information on Water Data" (1972), "Water Resources Regions and Subregions for the National Assessment of Water and Related Land Resources" by the U.S. Water Resources Council (1970), "River Basin of the United States" by the U.S. Soil Conservation Service (1963, 1970), "River Basin Maps Showing Hydrologic Stations" by the Inter-Agency Committee on Water Resources, Subcommittee on Hydrology (1961), and State planning maps.
The Political Subdivision has been adopted from "Counties and County Equivalents of the States if the United States" presented in Federal Information Processing Standards Publication 6-2, issued by the National Bureau of Standards (1973) in which each county or county equivalent is identified by a 2-character State code and a 3-character county code.
The Regions, Subregions and Accounting Units are aggregates of the Cataloging Unites. The Regions and Sub regions are currently (1978) used by the U.S> Water Resources Council for comprehensive planning, including the National Assessment, and as a standard geographical framework for more detailed water and related land-resources planning. The Accounting Units are those currently (1978) in use by the U.S. Geological Survey for managing the National Water Data Network.
This map was revised to include a boundary realinement between Cataloging Units 10140103 and 10160009.
