A dozen wells used to pump oil-and-gas in California’s Central Valley ended up ordered to shut down production to protect underground drinking-water from contamination, state officials said.
The operators of 10 oil wells in Kern County voluntarily stopped production, while two received cease-and-desist orders, said Steven Bohlen, head of oil, gas and geothermal resources for the California Department of Conservation.
Groundwater surrounding the wells will now undergo testing for traces of contamination.
The action came after a review found more than 2,500 instances when the state authorized the injection of oilfield waste into protected water aquifers that could see use for drinking or irrigating crops.
In addition, California — the nation’s leading agricultural state — enters a fourth drought year with farmers relying heavily on scarce underground water supplies.
“It doesn’t necessarily mean that the aquifers have been spoiled,” Bohlen said.
He said another 11 wells shut down last year, and so far testing has found no evidence of contamination.
Years of confusion, lax oversight and miscommunication among state and federal regulators are to blame for injecting protected groundwater with the waste, said a separate report made public Tuesday by California’s Environmental Protection Agency.
It found the problem first came to light in 2011, when a state official from Sacramento temporarily working in a field office found discrepancies in records. One set said 11 aquifers could end up used for injections, while another set said they enjoyed protection.
State officials continue to review oil-drilling permits to correct errors.