How likely is it that something might, in Paula’s words, “go horribly wrong”? That’s the core of the debate over fracking nationwide, and it’s complicated by a knowledge void. “The research is not keeping up with the pace of growth,” says Rob Jackson, a professor of earth sciences at Stanford University. “We’ve been playing catch-up in the scientific community, and that’s especially true for the realm of potential human health interactions.”
Oil and gas companies have fractured rocks since the late 1940s, albeit on a smaller scale than today. “This technology has never been associated with groundwater contamination in California,” says the petroleum association’s Hull. Some scientists feel hopeful the Golden State will maintain a healthy track record even as hydraulic fracturing or other well-stimulation methods ramp up. “Drilling for oil is a large-scale industrial process,” says Mark Zoback, who is a professor of geophysics at Stanford and an industry consultant. “There are a lot of things that can potentially go wrong. But if you follow best practice, and you get good regulations and enforce them, it can be done safely.”
Still, water contamination elsewhere shows that fracking is hardly foolproof. Researchers at The University of Texas at Arlington have discovered elevated levels of arsenic, selenium, and strontium—sometimes exceeding the government’s safety thresholds—in private drinking-water wells near drilling sites in Texas’s Barnett Shale. Likewise, Jackson and his former colleagues at Duke University have found heightened levels of methane and other gases in the water wells of Pennsylvanians living near Marcellus Shale fracking sites.
“It’s very easy to say, rhetorically, that there haven’t been any instances of water contamination documented in the state, so what’s there to worry about,” says environmental scientist Michael Kiparsky, associate director of the Wheeler Institute for Water Law & Policy at the University of California, Berkeley. But there’s a logical flaw in that reasoning, he says: Unlike the Marcellus and Barnett, the Monterey has never had high-intensity fracking on the same scale. Moreover, Kiparsky says, it could take decades or longer before contamination migrates far enough to be detected. “The problem then becomes similar to Superfund sites, where the activity that caused the pollution didn’t come to light as hazardous until later, and often until the perpetrator was long gone.”
Researchers do know there are plausible mechanisms for contamination. Fracturing shale also cracks the rock above it, says Anthony Ingraffea, a professor of civil and environmental engineering at Cornell. “You’re damaging what Mother Nature has provided over the last 300 million to 500 million years as a natural cap,” he says. “Over some period of time, there’s a possibility that the damage will allow gas or oil or other hydrocarbons to leak upward.”
The weakest links in the safety chain, according to experts, are the steel casings and cement that line the wells underground. They’re designed to isolate harmful chemicals from the surrounding environment, but they’re far from infallible—6 to 7 percent of new wells drilled in Pennsylvania over a three-year period had “compromised structural integrity,” according to Ingraffea’s research. The worst breaches can poison drinking or irrigation water, and Ingraffea says this “is undeniably happening, has happened, will always happen. And it’s not rare.” In December, the U.S. Environmental Protection Agency’s inspector general released a report on the dangerous levels of carcinogenic benzene and explosive methane in drinking water in Parker County, Texas, near Fort Worth. A gas-production well used in fracking “was the most likely contributor to the contamination of the aquifer,” the report noted.
Ingraffea and Kiparsky fear that California oil operations could prove particularly vulnerable to well failure because of their proximity to earthquake faults. “The state is a very seismically active region,” Kiparsky says. “Might seismic activity cause the type of damage to cementing and casing that could lead to more contamination of groundwater?”