Three years of drought have taken a heavy toll on California groundwater supplies, yet thousands of additional wells have been drilled this year, a state report released Tuesday said.
Nearly 250 new wells went into Merced County, about 200 into Stanislaus County and more than 370 each into Fresno and Tulare counties from January through September, charts released by the California Department of Water Resources show.
Hundreds more wells were drilled in Butte, Kern, Kings and Shasta counties. Fewer than 50 wells went into San Joaquin County.
But the report warns that those numbers are likely low because the drillers typically wait months before turning in their well-completion reports. So the full scope of the drilling surge may not be known until next year.
Gov. Jerry Brown this year initiated laws to start managing underground water in California, the last Western state to take such steps. But those plans could take years to be developed, officials said.
“If we fail to manage our groundwater basins sustainably, we risk losing the water supply savings account that can help cities, farms and businesses surviving drought with minimal disruption,” said Mark Cowin, director of the Department of Water Resources.
California risks overdraft, which Cowin said could permanently damage the naturally occurring underground water for future generations.
In years of normal rain and snowfall, groundwater accounts for 40 percent of supplies for farmers and communities, and the report says that in times of drought, that increases to 60 percent.
That increased pumping is causing problems.
The San Joaquin River Basin is among those identified as having notable decreases in groundwater levels. Maps included in the report show the San Joaquin Valley covered with red dots, indicating water levels have dropped by more than 10 feet since 2010.
In some parts of Merced County, the report shows water levels plunged nearly 50 feet during the past year.
Excessive groundwater pumping, the report says, also is causing ground levels to drop, a phenomenon called land subsidence. That, too, is apparent in Merced, according to the maps.
The Associated Press contributed to this story.
Bee staff writer J.N. Sbranti can be reached at firstname.lastname@example.org or (209) 578-2196.