Land in the Central Valley is sinking so much from over-pumping of groundwater in the drought that water officials plan to press for new laws to limit well drilling to slow the damage.
Jeanine Jones of the California Department of Water Resources said Thursday that sinking land threatens to limit up to one-fifth of water deliveries to central and Southern California as part of the state's vital north-south water project.
NASA satellite images show the land sinking at a troubling pace.
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The 444-mile California Aqueduct provides water to 25 million people and nearly one million acres of farmland. Officials said that since 2015, sections of the concrete canal have dropped more than two feet in places.
"The rates of San Joaquin Valley subsidence documented since 2014 by NASA are troubling and unsustainable," said DWR Director William Croyle. "Subsidence has long plagued certain regions of California. But the current rates jeopardize infrastructure serving millions of people. Groundwater pumping now puts at risk the very system that brings water to the San Joaquin Valley. The situation is untenable."
A previous report prepared by NASA showed record rates of subsidence, the gradual sinking of land, particularly near the Central Valley communities of Chowchilla and Corcoran, according to the DWR. More NASA aerial radar mapping showed the sinking caused by groundwater pumping caused the Aqueduct to drop by more than two feet near Avenal in Kings County, reducing how much water can flow through the segment, according to the DWR.
San Joaquin land subsidence isn't a new problem -- it was first observed in the 1920s -- but authorities have heightened concerns due to the NASA research results and heavy reliance on groundwater for irrigation during California's historic drought. Aqueduct problems due to sinking land have required repairs to canal linings, bridges and other structures along the canal's path.
Drought conditions have eased after January's strong winter storms. Eleven percent of the state remains under severe drought, down from 82 percent at this time last year, according to Thursday's Drought Monitor report.
NBC4's Jonathan Lloyd contributed to this report.