Parched California Tries to Grab Storm Water before it Escapes
A network of basins and wells, designed by geologists, can channel storm runoff into natural underground vaults before it vanishes into the sea
As surface water has dwindled during California’s epic drought, desperate farmers and municipalities have staged a run on other sources: the state’s vast underground hydrological savings banks, such as aquifers beneath the Sacramento and San Joaquin river basins. Before the great dry spell, about 40 percent of California’s water supply came from these underground reservoirs. But by 2015, the percentage had jumped to 75.
Refilling these vaults won’t be easy because they’ve been drained so heavily. In California’s Central Valley, groundwater levels have plummeted up to 100 feet lower than previously recorded. Restocking is also hard because an aquifer "is more like a colander than a bank,” says Andrew Fisher, a hydrogeologist at the University of California, Santa Cruz. As some water trickles in, other water leaks out—into streams, lakes, and wetlands.
But an underground refill is crucial, so Fisher has developed a scheme to increase the water going in. The idea is to grab stormwater that typically rushes off into waterways and out to the Pacific Ocean. Fisher plans to capture some of that water in special ponds and wells designed to allow water to trickle through the soil down to the aquifers below. Particles and microbes in the soil should help cleanse the water of contaminants that it picked up, such as nitrogen pollution from agricultural runoff.
A pilot project is already underway in the state’s Central Coast, and on March 16, a local water management agency will decide whether to approve three additional restoration projects.