Codes for the Identification of Hydrologic Units in the United States and the Caribbean Outlying Areas

U.S. Geological Survey, Geological Survey Circular 878-A

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This report presents and describes codes used for the identification of hydrologic units in the United States and the Caribbean outlying areas. The codes identify a hydrologic system that; divides the United States and the Caribbean into 21 major regions . These :regions are further subdivided into approximately 2,150 units that delineate river basins having drainage areas usually greater than 700 square miles. The codes provide a standardized base for use by water-resources organizations in the storage, retrieval., and exchange of hydrologic data; the indexing and inventorying of hydrologic data and information ; the cataloging of water-data acquisition activities; and a variety of other applications.

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U.S. Department of the Interior, U.S. Geological Survey
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