SummaryAnnual withdrawal of ground and surface water as a percent of total annually renewable volume of freshwater. General Information about this IndicatorWhat is it?: Groundwater withdrawals and recharge are an essential part of California’s interaction with groundwater as a resource for economic activities and health. How these occur and the net change in groundwater availability changes the future availability of ground water and thus sustainability of California. In a project in the Napa watershed, led by Napa County, statistically significant decline in a groundwater basin was an important indicator of sustainable water availability.