Digital representation of 1:1,000,000-scale hydrographic areas of the Great Basin

Hydrographic areas (HA) in Nevada were delineated by the U.S. Geological Survey (USGS) and Nevada Division of Water Resources in the late 1960s for scientific and administrative purposes. The official HA names, numbers, and boundaries continue to be used in USGS scientific reports and Nevada State Division of Water Resources administrative activities. HAs for the Great Basin region of the United States were mapped in the late 1980’s as part of a USGS regional assessment of aquifer systems in the Great Basin. The Great Basin HAs are being published in digital format to document the data as the basic accounting unit for past and recent hydrologic investigations in the Great Basin.