The Livermore Valley AVA is an American Viticultural Area in Alameda County, California, surrounding the city of Livermore in the Tri-Valley region. Both the AVA and the city are named after Robert Livermore, a landowner whose holdings encompassed the valley. The groundwater basin underlying the valley is the Livermore Basin, the largest sub-unit of which is the Mocho Subbasin. The Livermore Basin is one of five aquifers in the San Francisco Bay Area that supply most of the metropolitan Bay Area population. The entire Livermore Basin aquifer faces a concern over elevated total dissolved solids by the year 2020 due to an expanding human population leading to higher rates of return water flows to the aquifer containing certain salts.