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Hydrologic Unit Boundaries

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Hydrologic unit boundaries at the 2-digit (Water Resource Region), 4-digit (Subregion), 6-digit (Accounting Unit) and 8-digit (Cataloging Unit) level are shown in different colors and line thicknesses.

Cautions for this Product:


Source: USGS


Aggregate Layer: 8 Digit Hydrologic Units
Other Layers Displayed: 6 Digit Hydrologic Units, 4 Digit Hydrologic Units, 2 Digit Hydrologic Units


Hydrologic units:
A hierarchical system developed by the U.S. Geological Survey that divides the United States and the Caribbean into 21 major regions, 222 subregions, 352 accounting units, and further subdivided into 2,150 cataloging units that delineate river basins having drainage areas usually greater than 700 square miles. [USGS]

Product Information

Product ID: 2143
Production Date: 7/18/97
Product Type: Map

For additional information contact the Resources Inventory and Assessment Division. Please include the Product ID you are inquiring about. or 1400 Independence Avenue SW - P.O. Box 2890 - Washington D.C. 20013. If you use our analysis products, please be aware of our disclaimer.