california farm
Agricultural farm land is shown next to the desert in the Imperial valley near El Centro, California May 31, 2015.
Though California's drought may be officially over, the water scarcity has left a mark on farms.

According to a new NASA report, land in Central Valley — one of California's most productive agricultural regions — is sinking quickly due to heavy groundwater pumping during the drought.

Farmers have been pumping groundwater for decades, including at the height of the most recent drought from 2011 to 2016, when surface water was extremely scarce. Many factors contributed to California's drought, including changes in air circulation and wind speed off the coast, driven in part by global warming. Farmers and other landowners gathered water by pulling it from the ground, but the process also caused the ground to sink.

As Grist notes, a 2015 report found that farmland in the San Joaquin Valley, located between San Francisco and Sacramento, sunk at record levels from water pumping. Now, the situation has worsened in other locations, according to the NASA report.

Some parts of the Central Valley are plunging a foot per year. The country's largest-ever subsidence caused by groundwater pumping is in an area southwest of Mendota, California, where the water table (the ground level beneath Earth's surface) sunk 400 feet in the early and mid-19th century.

If the state's farmland continues to sink, it could hurt the entire country's agricultural system since nearly half of American produce and meat comes from California. (Drying out the soil makes for harsher growing conditions.) Large amount of sinking can change how rivers and streams flow, which can lead to water infrastructure damage.

The California Aqueduct and farm fields are seen in the Central Valley in Coalinga, California, United States May 6, 2015.
Groundwater pumping was largely unregulated until recently, which the LA Times says has "created a crisis" for California. Overpumping in the Central Valley has depleted water reserves by almost 80 million acre-feet since 1962. In 2014, the state's governor, Jerry Brown, instituted the Sustainable Groundwater Management Act, which requires local agencies to create plans for monitoring groundwater pumping — but a number of groups have struggled to organize and come up with changes so far.

Some organizations, like the Community Water Dialogue, are exploring methods for recycling the region's wastewater and aquifers that would capture and store rainwater and other runoff.

Made up of local landowners and growers, the group says much of their work is aimed at farmers, who use about 85% of the region's water. Adopting new technologies, like soil moisture probes that provide real-time data, could help conserve water — even if it's pumped from the ground.