What I learned reporting on the groundwater science on Central California’s oil fields

In San Luis Obispo County, the Arroyo Grande oil field has been in production since the early 1900s. After decades of simply pumping up the readily accessible crude, subsequent owners of the oil field had to use more intense “recovery methods” to get to the oil and get it out of the ground. That also meant the creation of more wastewater, as enhanced oil recovery methods require a lot of water to work. For decades now, oil companies have been pumping that wastewater, known to include carcinogenic chemicals, deep back underground across California, via wells penetrating the same oil field. This practice is standard in the industry and fully backed by federal and state regulatory bodies.

When the national Safe Water Drinking Act went into effect in 1974, it meant oil companies had to get start getting permission from the U.S. Environmental Protection Agency to continue to dispose of this wastewater underground, and prove that it wasn’t contaminating underground sources of public drinking water. Looking at the “proof” supplied by oil companies explaining how underground injection is infallibly safe, I found it seemingly insufficient, given the advances in science and technology since the early 70s. 

At past public hearings on the county level about the oil company’s expansion plan, I could see from meeting minutes that hundreds of residents had turned out to protest. There were also supporters, who spoke about the jobs the expansion would create and the tax dollars generated. Public health and the safety of nearby underground drinking water sources were often mentioned by those in opposition to the plan. 

At the end of 2017, I reported on how the latest owner of the Arroyo Grande Oil Field was trying to move forward on expanding the number of steam-injection oil wells. This would triple of the size of the underground area the oil company would inject wastewater back down. Owner Sentinel Peak Resources needed an “aquifer exemption,” from the EPA, meaning that underground area was exempt from protection under the Safe Water Drinking Act. When I heard of nearby neighbors expressing concern that this expansion would threaten the safety of their drinking water, I wanted to explore these issues in a larger reporting project.

I also found it interesting that despite recommending to the U.S. EPA approval of the aquifer exemption, DOGGR had revised the boundary of the aquifer area to avoid two nearby drinking water wells. A scientist with the Center for Biological Diversity told me this was because DOGGR wasn’t entirely confident that injected wastewater wouldn’t migrate after all. 

When the first oil company started drilling in the Arroyo Grande oil field over a hundred years ago, it was an isolated, rural facility. But now the oil field is surrounded by development on all sides, and more than one hundred homes depend on drinking water from private wells immediately adjacent to the oil field, and many hundreds more in neighboring canyons. By looking at how oil companies and the state regulatory body—the Department of Oil, Gas and Geothermal Resources, or DOGGR—determine the safety of underground injection of wastewater, I hoped to answer this question: were neighbors justified in their concerns over possible contamination of drinking water wells?

I approached this question by trying to understand how groundwater science is conducted, and contacted dozens of hydrogeologists, geologists and scientists of similar disciplines to help me figure it out. I conducted several interviews at the Berkeley National Lab, in hopes of hearing independent perspectives on groundwater science. In every instance, the scientific experts would not speak to the specific situation at the Arroyo Grande oil field, saying the particular underground geology of each oil field is unique. Therefore, without studying the Arroyo Grande oil field specifically, they could not guarantee whether wastewater injected underground would migrate to other areas or not. But in general, these sources said, current working theories of subsurface hydrology describe a much more fluid and dynamic environment than previously understood. And that climate change is a wild card that could significantly alter how subsurface hydrological systems work in the future.

I also requested interviews with DOGGR staff and scientists, the people responsible for looking at the oil company’s evidence of underground injection safety and determining if it was sufficient. In 2009, DOGGR admitted it had been granting aquifer exemptions to areas that didn’t meet the Safe Water Drinking Act exemption criteria, and that oil companies had been injecting wastewater into areas underground that could threaten or contaminate public drinking water sources since the early 1980s. After almost a decade of intense scrutiny, sanctions and damning reports, the state agency operates, in terms of media relations, like a fortress under siege. Its PIO refused to allow any DOGGR scientific staff to speak on the record, and while the agency contends the vast majority of oil industry data and records are publicly available on its website, the available information and data are extremely difficult for a non-scientist to understand. In reporting this subject into the future, I hope to partner with a freelance science writer with deep knowledge of the oil industry to help decipher what useful information is publicly available, and crucially, what is missing from the public record. 

Looking back on the segments I produced for this project, I realize many more voices among the concerned neighbors would have helped form a more powerful narrative to frame the reporting. One potentially effective approach would have been to type up a flyer explaining my reporting project, asking for interested sources to contact me, and distribute that widely as possible in the area. I also wasted a good deal of time trying to reinvent the wheel; approaching the topic as uncharted territory, aiming to produce a completely novel and comprehensive digest of the subject. 

After a year of working and thinking on this topic, I realized it is too broad in scope for it to be a successful reporting project for the California Fellowship. Had I the chance to do it over, I would narrow the scope significantly to focus only on one aspect. Answering the question whether oil field neighbors are justified in their concerns over possible contamination of their drinking water wells proved too complex for the time and resources I had to commit to the project. While I plan to continue reporting on subject of underground injection throughout my career, I hope others will pursue questions about the practice of underground wastewater injection, and continue to examine the methodology DOGGR and the EPA employ to determine its safety.