For Immediate Release, August 23, 2021


Victoria Bogdan Tejeda, Center for Biological Diversity, (724) 317-7029,
Mary A. Ciesinski, ECOSLO Environmental Center of San Luis Obispo, (805) 710-8021,

Records Reveal Years of Illegal Oil Drilling at California’s Arroyo Grande Oilfield

Discovery Comes Ahead of San Luis Obispo Hearing on Oilfield Expansion

SAN LUIS OBISPO, Calif.— The Center for Biological Diversity informed San Luis Obispo County leaders today that the operator of the Arroyo Grande oilfield has been drilling illegal oil wells for years. Evidence of the illegal drilling was uncovered by the Center through a recent public information request.

In a letter to county authorities, the Center detailed its findings that despite a permit that expired in 2015, the county has improperly given operator Sentinel Peak Resources approval for dozens of new wells since 2017.

Newly revealed records show the company is abandoning and plugging old wells and drilling new ones misleadingly labeled as “replacements,” skirting county permitting requirements and state environmental laws for new wells.

“It’s unbelievable that the county is letting Sentinel drill away illegally with this fictional claim of ‘replacement’ wells,” said Victoria Bogdan Tejeda, an attorney at the Center’s Climate Law Institute. “This is like a plumber saying they replaced the faucet in your kitchen by installing a new sink in your bedroom. It doesn’t make any sense, and the county is at best ignoring this dangerous deception.”

By law the company should have drilled no new wells since 2015, when Sentinel’s request to extend its permit was put on hold pending a Center appeal. County authorities have yet to hear that appeal.

Instead, records reveal that since 2017, the county has quietly authorized 37 new wells — more wells than the company asked for in its initial extension request.

The wells authorized at Arroyo Grande include many injection wells that use huge amounts of water and pose extreme risks to people’s health and the environment. A recent Center report found that Arroyo Grande is the fourth most carbon-polluting oilfield in the state.

“There are laws and procedures in place that should be protecting our community, but they have to be enforced,” said Mary A. Ciesinski, executive director of ECOSLO – the Environmental Center of San Luis Obispo. “Oil drilling and steam water injection compromise the safety of our local freshwater resources and threaten our climate. By allowing expanded drilling without proper permitting, the state and county are failing to protect the health and safety of our people and natural resources.”

The revelations come ahead of a planned hearing on Oct. 19, when the Board of Supervisors will decide whether to let Sentinel drill 31 additional wells.

The Center is calling on the board to grant its appeal and deny Sentinel’s 2015 extension request, stop permitting so-called replacement wells and rescind all unlawful approvals. It’s also calling for the county to institute a public process for any further expansions or drilling in Arroyo Grande.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.