Why are drinking water wells going dry in the valley?
In the San Joaquin Valley, groundwater is the primary source of drinking water. While groundwater levels in the valley have generally been declining for decades, the problem of overdraft—which can cause shallow wells to run dry —is particularly acute during droughts as surface water supplies for irrigating crops are limited. This especially affects domestic wells and small community wells, which tend to be shallower than those used for irrigation or large urban water systems. During the 2012–16 drought, 2,600 well-dependent households reported water shortages across the state; almost 80% of these were in the San Joaquin Valley. We estimate that the valley’s total number of dry domestic wells was likely higher (see map below, on left). Many small community wells also faced shortages.
Does SGMA protect wells from running dry in the future?
SGMA was enacted to address the negative consequences of groundwater overdraft. Declining water levels is one of the six undesirable results that plans must avoid. Local agencies are tasked with setting minimum water level thresholds to avoid effects that are “significant and unreasonable”—something that can vary with local conditions.
Allowing some flexibility is important, because very restrictive thresholds would require immediate and costly cuts in groundwater pumping. Yet in many places, additional water level declines can render shallow drinking water wells useless. If agencies choose to allow continued pumping to avoid major disruptions in the regional economy, they are required to mitigate any significant and unreasonable effects. Options include covering the costs of drilling deeper wells or providing an alternative water supply.
How do groundwater plans address risks to domestic wells?
The plans reflect a range of approaches—as shown in the map below, on the right. In several basins, plans set water level thresholds to protect domestic wells from going dry. Some other plans acknowledge that their thresholds might […]