The state of California oversees water level monitoring for its 515 designated groundwater basins. Periodically, each basin and subbasin are scored on a statewide scale and given a priority level. This score is based both on elevation trends and the intensity of usage. Thus while Death Valley is considered very low priority, nearly all basins in the ag-heavy Central Valley are medium and high. Related article »
Source: California Department of Water Resources Sustainable Groundwater Management Act (SGMA) Basin Prioritization