Create an Account - Increase your productivity, customize your experience, and engage in information you care about.
The Sustainable Groundwater Management Act (SGMA) defines sustainable groundwater management as managing and using groundwater without causing undesirable results such as: chronic groundwater level declines, groundwater storage reductions, seawater intrusion, water quality degradation, land subsidence, and surface water depletions. SGMA requires that groundwater basins classified as either medium or high priority by the California Department of Water Resources achieve sustainable groundwater management within 20 years of adopting a Groundwater Sustainability Plan.
Show All Answers
SGMA defines undesirable results as “one or more of the following effects caused by groundwater conditions occurring throughout the basin:
Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon. Overdraft during a period of drought is not sufficient to establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reductions in groundwater levels or storage during a period of drought are offset by increases in groundwater levels or storage during other periods.
GSPs must address undesirable results and undertake management actions to ensure that they are avoided within 20 years of GSP adoption.
As part of SGMA, DWR recognizes 5 groundwater basins and subbasins in Napa County. Here is the list of the basins and subbasins, along with the priority that DWR gave to each basin:
High and medium priority basins are subject to a variety of rules and regulations under SGMA. Low and very low priority basins are not required to take any action at this time. Learn more about requirements for each priority level here.
Napa Valley Subbasin is categorized by DWR as one of 46 high priority groundwater basins statewide. Medium and high priority basins are subject to the Sustainable Groundwater Management Act (SGMA) requirements. The Department of Water Resources (DWR) prioritized all basins in the state according to the following criteria:
The Napa Valley Subbasin is categorized as high priority primarily due to the amount of irrigated lands, the density of wells, projected population growth, and the degree to which people rely on groundwater in the Subbasin.
DWR’s basin prioritization process is not a determination of whether groundwater basins are being managed sustainably. Rather, it is a way for DWR to determine the reliance on groundwater in individual basins across California and whether those basins should be subject to the requirements of SGMA.