Most of state’s fracking waste left in unlined pits, study finds



less In this March 29, 2013 file photo, workers tend to a well head during a hydraulic fracturing operation at an Encana Oil & Gas (USA) Inc. gas well outside Rifle, in western Colorado. The Obama administration is proposing a rule that would require companies that drill for oil and natural gas on federal lands to publicly disclose chemicals used in hydraulic fracturing operations. The new "fracking" rule replaces a draft proposed last year that was withdrawn amid industry complaints that federal regulation could hinder an ongoing boom in natural gas production. In this March 29, 2013 file photo, workers tend to a well head during a hydraulic fracturing operation at an Encana Oil & Gas (USA) Inc. gas well outside Rifle, in western Colorado. The Obama administration ... more Photo: Brennan Linsley, Associated Press Photo: Brennan Linsley, Associated Press Image 1 of / 8 Caption Close Most of state’s fracking waste left in unlined pits, study finds 1 / 8 Back to Gallery

More than half of the wastewater from fracked oil wells in California is disposed of in open, unlined pits and could contaminate groundwater, according to a state-mandated study of hydraulic fracturing issued Thursday.

The California Council on Science and Technology study presents a cautious assessment of fracking in the state. And it’s not likely to defuse the political fight over fracking, with both the oil industry and its opponents on Thursday claiming vindication in its findings.

The study authors, many of them from Lawrence Berkeley National Laboratory, stress that they found no cases in California of groundwater contamination due to fracking or stimulating oil wells with acid. Nor did they find confirmed cases in which disposal of oil-field wastewater underground triggered earthquakes, a phenomenon that has caused a surge of tremors in Oklahoma.

But no state agency has systematically searched for water contamination or a link to earthquakes, they write. And fracking can use so many different chemicals — two-thirds of which have unknown effects on the environment — that contamination could slip by undetected.

Contamination question

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“We found little evidence of any impacts, of groundwater contamination, and we found few studies that actually looked for that contamination,” said Jane Long, lead researcher on the study’s science team. “The fact that we haven’t looked for it is an issue.”

Dumping fracking wastewater into unlined, open-air pits could contaminate aquifers used for drinking and irrigation and should either be closely monitored or stopped altogether, the authors write. More than 900 such pits, many without proper permits from the state, dot the oil fields of the San Joaquin Valley, and some of them lie atop usable aquifers.

Attention to disposal

“This is a source of contamination that needs to be managed,” Long said. “The water needs to be tested and treated, or the pits need to be closed.”

The state should also pay special attention to areas where oil companies are fracking shallow wells that lie close to drinking-water supplies. The authors found several places, in both the San Joaquin Valley and the densely populated Los Angeles Basin, where fracking has happened at depths less than 1,000 feet.

Fracking uses a high-pressure blend of water, sand and chemicals to crack rocks and release oil or natural gas. Acid stimulation employs powerful acids to open channels within the rocks and can be used on its own or in conjunction with fracking.

Environmental groups pushing for a statewide fracking ban seized on some of the report’s details to describe the practice as an ongoing threat to the state’s air, water and residents.

“This study exposes California’s oil producers as the polluters that they are,” said Andrew Grinberg, the oil and gas program manager for Clean Water Action. “The science clearly identifies numerous threats from fracking and other oil-production activities that California’s laws, regulations, enforcement and available data do not adequately address.”

Industry’s view

The oil industry, similarly, pointed to the study as further proof that fracking has not caused widespread harm.

“The extensive research confirms what regulators and scientists have said previously: There is no evidence of groundwater contamination or induced earthquakes to date in California, after many decades of the routine use of hydraulic fracturing in the state,” said Dave Quast, California director for Energy in Depth, an oil industry public outreach campaign.

The study, however, could produce results in Sacramento.

Sen. Fran Pavley, D-Agoura Hills (Los Angeles County), said she would amend a pending bill to phase out wastewater disposal pits. Pavley wrote the 2013 law regulating well-stimulation techniques that triggered Thursday’s study.

The pits, she said, “pose a risk to the health of animals and humans.”

Minimal water use

The study’s authors emphasize that fracking in California uses far less water than in other states. That’s largely because the wells fracked here tend to be shallower and shorter than in other oil-producing regions and seldom use horizontal drilling. Fracking also requires significantly less water than other oil-production techniques common in California, such as flooding old oil reservoirs with steam.

But the council, created in 1988 to advise the Legislature on technical issues, wasn’t authorized to conduct its own water-quality tests. Instead, the group was asked to survey and analyze all the data it could find on fracking in the state.

Large gaps in the data remain.

For example, the authors found only one small California earthquake in 1991 that had been attributed to fracking. They found no recorded cases in the state of earthquakes being triggered by the underground disposal of wastewater from fracking and other forms of oil drilling.

But the possible link between tremors and wastewater disposal wells in California has not been researched in a systematic way, the authors wrote. The study includes a map of disposal wells and earthquake epicenters that shows two areas with concentrations of both, in eastern Ventura County and near Coalinga in the San Joaquin Valley. But further study is needed to tell if one caused the other, Long said.

“We do see some situations where injection sites are co-located on the map with earthquakes, but we don’t know if they’re correlated in time or correlated in depth,” she said.

David R. Baker is a San Francisco Chronicle staff writer. E-mail: dbaker@sfchronicle.com Twitter: @DavidBakerSF