Groundwater Info Center

Groundwater Basin Maps and Descriptions

There are currently 431 groundwater basins delineated, underlying about 40 percent of the surface area of the State. Of those, 24 basins are subdivided into a total of 108 subbasins, giving a total of 515 distinct groundwater systems. Many of the subbasin boundaries were developed or modified with public input, but little physical data. Because they should not be considered precise boundaries, a detailed local study should determine whether any specific area lies within a groundwater basin boundary.

Maps and individual basin and subbasin descriptions for each Hydrologic Region can be accessed below.

Enlarge map (PDF: 3.22 MB)
Download shapefile (ZIP: 3.39 MB)
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Basin descriptions are based on the best available information. In basins where many studies have been completed and the basin has been operated for a number of years, the basin response is fairly understood and the boundaries are well defined. Even in these basins, however, there are many unknowns and the boundaries may change as more information is collected and evaluated.