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Santa Clara County’s groundwater basins — critical sources of water that provide nearly half the drinking water every year for 2 million Silicon Valley residents — fell by up to 60 feet during the state’s recent historic drought due to heavy pumping.
Monitoring wells in the same area showed that the groundwater table fell by at least 60 feet during that time.
In 2015, Santa Clara County residents reduced water use 27 percent overall from 2013 levels.
And by 2017, when the wettest winter in 20 years caused downpours and floods, they were back to pre-drought levels, the district’s wells showed.
The study was published in the Journal of Geophysical Research, and also includes researchers from NASA’s Jet Propulsion Laboratory in Pasadena, UC Berkeley and Purdue University.
The water table fell nearly 200 feet from 1915 to 1960 as farmers and residents of growing suburbs increased their water use. Subsidence caused the ground to fall as much as 13 feet around San Jose. But when the water district began to construct local reservoirs, import water from the Delta and impose what’s commonly known as “the pump tax” to fund groundwater recharge programs, the water table began to slowly recover.