Nearly two months after lawmakers requested information about experimental oil extraction methods, state regulators acknowledged this week they have not monitored a host of practices used to access shale oil in California, some of which involve the injection of dangerous chemicals underground.

Sen. Fran Pavley (D-Agoura Hills) and Assemblyman Wesley Chesbro (D-North Coast) requested the information May 30 in a letter to California Department of Conservation Director Mark Nechodom, who oversees oil and gas wells in California. They requested information about well stimulation methods such as acid stimulation, in which large volumes of corrosive acids are injected underground to dissolve shale rock.

Industry statements have suggested acid simulation could be as important for accessing California’s shale oil as the widely publicized hydraulic fracturing, or “fracking” method. In the letter, Pavley and Chesbro asked about the types of well stimulation, the chemicals used, the handling of wastewater, and the occupational, health and safety risks, among other questions.

In response, Nechodom wrote this week that his department’s Division of Oil, Gas & Geothermal Resources (DOGGR) has only “sporadic documentation” of well stimulation. He did not provide detailed answers, acknowledging the department does not oversee or track well stimulation in California (see attached letter).

In his letter, Nechodom said his division doesn’t have the resources to develop a database of well stimulation information because it would require the review of “thousands of scanned documents.” However, over the past three years DOGGR has voluntary declined to use additional staffing resources provided by the Legislature.

“Director Nechodom’s response confirms what we suspected, which is that DOGGR doesn’t know what, where, when, or with what chemicals well stimulation is being used in California,” said Briana Mordick, a staff scientist at the Natural Resources Defense Council and a former senior geologist for Anadarko Petroleum Corp.

Based on anecdotal evidence, Nechodom provided a partial list of chemicals, confirming that companies use dangerous substances such as hydrofluoric acid, a highly corrosive acid, and acetaldehyde, which is listed as a known cancer-causing agent under California’s Proposition 65.

“It is deeply concerning that dangerous acids and Proposition 65 chemicals are being pumped underground without any permits or oversight,” Pavley said. “Unfortunately, regulators have not deemed these activities worthy of monitoring. Director Nechodom’s letter reaffirms the need for legislation to force DOGGR to fulfill its legal responsibilities—protection of life, health, property and natural resources.”

Pavley is the author of Senate Bill 4, which would regulate fracking and other well stimulation practices and require an independent scientific study of the risks. The bill was approved by the Assembly Natural Resources Committee July 1 and will be heard by the Assembly Appropriations Committee in August.