The US Environmental Protection Agency has approved an aquifer exemption for the Arroyo Grande oil field near San Luis Obispo. This enables Sentinel Peak Resources, the current owner of the oil field also known as Price Canyon, to move forward with a planned expansion of wells for both enhanced oil recovery and dispoal of wastewater, or “produced water.” In a decision dated April 30, the director of EPA’s water division said the underground formation beneath the oil field does not, and will not in the future, serve as a source of drinking water due to the presence of “commercially producible quantities of hydrocarbons.”