Fossil fuels don’t just damage the planet by emitting climate-warming greenhouse gases when they are burned. Extracting coal, oil and gas has a huge impact on the surface of the earth, including strip mines the size of cities and offshore oil spills that pollute country-sized swaths of ocean. 

Years of research has shown how the fracking boom has contaminated groundwater in some areas. But a study published on Thursday in the journal Science suggests there is also a previously undocumented risk to surface water in streams, rivers and lakes.

After analyzing 11 years of data, including surface water measurements in 408 watersheds and information about more than 40,000 fracking wells, the researchers found a very small but consistent increase in three salt compounds—barium, chloride and strontium—in watersheds with new wells that were fracked. While concentrations of the three elements were elevated, they remained below the levels considered harmful by the EPA. 

Such salts are commonly found in water coming from newly fracked wells, making changes in their levels good markers for fracking impacts on surface water, said co-author Christian Leuz, professor of international economics at the University of Chicago. The three economists who did the research specialize in studying the effectiveness of environmental regulations.

Though the impact the researchers detected was small, the data came from diluted water in rivers and streams that were often far from wells, Leuz said, so the concentrations could be higher farther upstream and closer to the fracking operations.

The findings suggest that the rapid pace of “unconventional oil and gas development,” like fracking, may be outrunning scientists’ ability to monitor its impacts on surface water. “Better and more frequent water measurement is needed to fully understand the surface water impact of unconventional oil and gas development,” said economist co-author Pietro Bonetti, with the University of Navarra, Spain. 

The researchers said they couldn’t determine human health impacts from the elements for two reasons, Leuz said.

First, “there is not enough public data to analyze potentially more dangerous substances,” he said, and second, ”there are limitations in available water-quality measurements.” Even though some states require fracking companies to disclose chemicals in their fluids, they aren’t always listed in public water monitoring databases, Leuz added. 

The 2005 amendment to the Safe Water Drinking Act, known as the Halliburton Loophole, also made tracking harder by exempting hydraulic fracturing fluids from the Safe Drinking Water Act, preventing the EPA from regulating fracking fluids.

A Step Toward Full Accounting of Fossil Fuel Impacts

As the United States seeks to dial back fossil fuel use, accurate environmental data is important for policy discussions about topics like carbon pricing, as analysts try to present a full accounting of how much fossil fuels cost, said co-author Giovanna Michelon, who researches sustainability accounting at the University of Bristol.

The study, she said, was started to determine if regulations requiring companies to disclose the contents of their fracking fluids had an impact on water quality during the fracking boom, when tens of thousands of wells were drilled in Pennsylvania and New York, and through a vast swath of the West, from Oklahoma and Texas through New Mexico, Colorado, Utah, Wyoming, Montana and North Dakota.

Around 2010, many states started regulating fracking which, along with technologies that allowed horizontal drilling for miles underground, drove the boom in  “unconventional oil and gas development” and obliged companies to disclose more environmental information related to fracking, including the chemicals in their fluids and details on wastewater management. 

“We wanted to see if the mandatory disclosure made their operations cleaner,” Michelon said. But as the researchers started collecting information on new wells and water quality, they realized that there wasn’t enough data to show that link, she added.

The data needs to be further analyzed to understand if requiring drilling companies to be transparent about what’s in their fracking fluids led them to clean up their operations, she said, but the study published today also provides important information for drafting regulations and focusing future monitoring and research on potential trouble spots that are more vulnerable to pollution. 

Early research on fracking impacts was mostly on groundwater contamination, but in 2016, the EPA published a report with a “more complete record of localized evidence,” that found the potential for surface water pollution under certain circumstances, Michelon said. 

Fracking, short for hydraulic fracturing, uses water laced with sand and a wide variety of additives to shatter rock deep underground and release gas or oil. Along with the fossil fuels and salts, the process often draws water that’s been trapped in the rocks to the surface. That water, along with the fracking fluid that comes back up from the well, is called “produced water,” which is contaminated with elements from underground, as well as the chemicals in the fracking fluid. If it can’t be treated to clean it, it’s often disposed of by shooting it into an “injection well” that stores it underground. Previous studies of surface water impacts suggest that improper management of that water is often the source of pollution.

“There are three potential channels that may be related to our results, but we are unable to discriminate or distinguish between them,” Michelon said. They include on-site spills and leakage, a long-term slow escape of water called leaching and improper disposal or treatment of wastewater, including “direct disposal of untreated wastewater,” which may be done illegally or permitted by insufficient regulation, she said.

The Critical Zone

Sue Brantley, a geochemist at Penn State, studies water in what she calls the critical zone—from treetops down to groundwater—because it’s where nearly all human interaction with water happens. For her, the new study partly answers a long-standing question.

“Is fracking affecting water in the critical zone to the extent that we need to do something about it?” asked Brantley, who was not a study author, but reviewed a draft of the report. The advanced statistical analysis used by the research team produced results that correlated fracking with changes to water chemistry. “I don’t think anyone has ever really seen that before,” she said.

“Those are the kind of numbers that a health expert needs to start doing assessments,” she said, adding that other studies have shown health impacts like babies with lower birth weights and higher rates of asthma in areas with fracked wells.

And even though the increases detected by the study are small, the findings hint at the looming problem represented by the massive amounts of tainted water produced by fracking. 

“We’re drilling a lot of deep holes into permeable rock, and those are conduits up into the critical zone—straws down out of our critical zone,” she said. “They can bring up elements and compounds that are potentially dangerous. You’re bringing up very concentrated brine, and when you look at how much brine is being collected from all the wells around the country, it raises concerns.”

Nichole Saunders, a fracking expert with the Environmental Defense Fund, said the new study can also be helpful as a baseline against which to measure future impacts to surface water. Since contamination often happens when water is being handled at the surface, the research may help show ways to reduce its effects.

“Is our regulatory system really ready to prevent contamination from these practices?” she asked. “These kinds of studies really make it that much more important to find out.”