A Sinking Feeling: Over-Pumping CA Groundwater

San Joaquin Valley Subsidence

San Joaquin Valley Subsidence (Source: JPL/NASA Report & Google Maps)

The immense importance of proper groundwater recharge was recently confirmed by NASA, who released data earlier this month showing that parts of California are quite literally sinking due to the over-pumping of groundwater. Among other effects, over-pumping groundwater aquifers can cause the soil to collapse and compact, causing the land to subside and, in the case of California’s San Joaquin Valley, jeopardizing water infrastructure that serves millions of people. “The sinking threatens to curtail as much as one-fifth of water deliveries through the vital California Aqueduct to San Joaquin Valley farms and millions of Southern California residents,” according to the Associated Press.

Source: Rancho California Water District (website)

Vail Lake (Source: Rancho California Water District website)

Another effect of over-pumping is poorer water quality. Some local water agencies are considering raising rates to buy imported water while it’s available again to allow for local water sources to recharge. One such agency is Rancho California Water District (RCWD), who can no longer draw from its alternative water source, Vail Lake, due to water quality issues. The dramatic lack of rainfall in the region threatened the local groundwater basin and forced RCWD to use Vail Lake in an effort to augment the local supply and keep rates low. Despite the recent storm events, the lake is reported to be at only one-quarter of its capacity and requires much more water in order for sediment to settle to the bottom. Buying imported water from the state water project is considerably more expensive than local water supply, but it allows time for both Vail Lake and the local groundwater basin to recharge.

While rate hikes are never ideal, recent massive storm events have lifted Northern California out of the drought and importing water from up north may indeed be the best option for still-parched Southern California as it works to recharge its local water sources.

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