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Last day for public input on proposed Arroyo Grande aquifer exemption

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The Arroyo Grande oil field along Price Canyon Road in San Luis Obispo County.

The deadline for public comment on a proposed expansion of oil drilling-related operations in San Luis Obispo County’s Price Canyon is 5 p.m. Friday.

The oil company Sentinel Peak Resources is seeking state and federal permission to drill hundreds of new and replacement wells in Price Canyon, and those new wells are partnered with a proposed expansion of the area - known as the Arroyo Grande aquifer - where the oil company could inject wastewater underground, tripling it in size. In order to move forward on the project, Sentinel Peaks needs what’s termed an aquifer exemption from the U.S. Environmental Protection Agency (EPA); to exempt that underground area from the national Safe Drinking Water Act.

The state agency in charge of regulating oil and gas operations is the Division of Oil, Gas and Geothermal Resources, also known as DOGGR. While the agency and the state and Central Coast water boards approved Sentinel Peak’s aquifer exemption application, the EPA asked for more study in 2016.

“The EPA was concerned about potential impacts to people's water wells and the surrounding areas. So they asked DOGGR to do more analysis, to see if it might affect the water wells,” said Maya Golden-Krasner, a senior attorney with the Center for Biological Diversity (CBD).

In 2016, the environmental group sued to stop the aquifer exemption, but lost in San Luis Obispo County Superior Court. CBD says there’s not enough evidence proving that when the wastewater is injected underground, it won’t contaminate area drinking water. After the EPA asked for more information, the state agency revised the boundaries of Sentinel Peak’s aquifer exemption.

“They ended up moving the boundary in, because they're concerned that perhaps - there's a tar seal boundary - that may not protect the water wells in that area,” said Golden-Krasner.

Christine Halley is a spokesperson for Sentinel Peak Resources.

“So the slight adjustment to the boundary that was made fits well within our plans for operations,” Halley said. “We respect that adjustment was made, in response to material that was brought forth in that area, and we can operate within that confinement.”

A grassroots group of residents who live around the Arroyo Grande Oil Field are trying to block the expansion, and support the Center for Biological Diversity’s efforts to derail the aquifer exemption.

Once the public comment period on this update to Sentinel Peak’s application, DOGGR forwards that public comment to the EPA, which makes the final decision. The EPA under the Trump Administration has approved several aquifer exemptions in 2017, and if the EPA signs off on the Arroyo Grande exemption, the CBD may challenge that decision in federal court, according to CBD spokesperson Patrick Sullivan.

Editor's note: emailed comments may be sent to For more information about how to submit public comment on the proposed aquifer exemption, navigate to:

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