SAN FRANCISCO (CBS/AP) — California is shutting down another 33 oilfield wells that state officials improperly permitted to inject into federally-protected water supplies.

The shutdowns were effective Thursday, and primarily affect oilfield injection wells in Central California’s Kern County. It’s the latest development following revelations that California gave oil companies permits to dump oilfield waste and production fluid into water aquifers that were supposed to be off-limits. The aquifers hold water clean enough to be current or potential sources of drinking water.

California shut down another 23 oilfield injection wells earlier in the year, and has promised a statewide review. Federal environmental officials have ordered California to bring its oilfield regulation back into compliance with the Safe Drinking Water Act.

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