From almost the first moment that drilling companies began using hydraulic fracture to extract previously unrecoverable deposits of oil and gas, those who lived near the drill sites began to complain of well levels that dropped, water that changed in color or taste, tests that indicated the presence of chemicals used in fracking—even water mixed with enough gas to make it flammable.
It was easy to understand the case for potential pollution through fracking. The whole point of the process was to force huge quantities of water, sand, and chemicals down pilot holes, fracturing shale deposits with hydraulic pressure. If the fracking process could break the shale containing oil and gas, what might it do to the strata containing water sources? Couldn’t they also be subject to fracturing, and contamination from both the chemicals used in the fracking and the oil and gas recovered?
On the other hand, it was also easy to understand the case against that kind of pollution. The shale deposits that were being fractured were far below—usually thousands of feet below—the layers of rock tapped for drinking water. In between those strata are generally found many units of shale, limestone, and other impermeable strata that should block any pollutants in moving from the targeted zone to the area were water is produced.
However, there are more steps to fracking than just breaking the rock. The water to be injected must be mixed with sand and chemicals on the surface before drilling, and it has to be stored following completion of the process. Both of those steps offer other opportunities for fracking chemicals to pollute surface or ground water.
Now the EPA has completed a study of pollution associated with fracking to determine whether or not the wells represent a danger to local groundwater sources. And the answer is: sometimes.
These activities can impact drinking water resources under some circumstances. Impacts can range in frequency and severity, depending on the combination of hydraulic fracturing water cycle activities and local-or regional-scale factors.
Sometimes yes, sometimes no is not an extremely satisfying answer. However, the EPA identified a series of circumstances that increase the threat, which, in a rational world, would lead to improved regulation of fracking sites.
Most of the circumstances leading to increased risk of pollution seem clear enough:
Large spills of fracking fluids are a bad thing, and so are injection wells that lack the solid casing designed to protect zones above the targeted area for fracking. Wells without well-engineered casing can also allow water, gas, and oil to move between the target zone and groundwater deposits by using the well itself as a kind of expressway to bypass other strata.
The report also warns against bad procedures for storing water after drilling. That includes dumping the waste into open pits, and directly discharging this waste water into streams (which was absolutely common during the earlier period of coal bed methane fracking in Wyoming). Also on the bad list: injecting hydraulic fracturing fluids directly into groundwater resources, which, you have to assume, must have happened somewhere for it to make the report.
How often does drinking water contamination happen in association with fracking? Even after this long report, the EPA pleads “we don’t know” when it comes to a general prediction, but they are willing to take a shot at statistics for specific areas.
The available data and information allowed us to qualitatively describe factors that affect the frequency or severity of impacts at the local level. However, significant data gaps and uncertainties in the available data prevented us from calculating or estimating the national frequency of impacts on drinking water resources from activities in the hydraulic fracturing water cycle. The data gaps and uncertainties described in this report also precluded a full characterization of the severity of impacts.
Without those numbers, the EPA results can definitely be used to set new national standards for the design and placement of well casings, the storage and injections of fracking fluids, and the storage of waste water. However, it’s tougher to make a general prescription about how fracking activity should be limited around populated areas and in areas around significant groundwater sources.
Which is happening more often than you may think.
Between 2000 and 2013, approximately 3,900 public water systems were estimated to have had at least one hydraulically fractured well within 1 mile of their water source
The EPA also issues what seems like a pretty straightforward warning: if you live near an area with fracking, you’re at a greater risk from fracking contamination.
When hydraulically fractured oil and gas production wells are located near or within drinking water resources, there is a greater potential for activities in the hydraulic fracturing water cycle to impact those resources.
It’s not always. It’s not never. And the contamination can be minor or severe. But there are risks to be found at every stage of the process.
- Spills of additives and hydraulic fracturing fluids can reach groundwater and surface water resources.
- Below ground pathways, including the production well itself and newly-created fractures, can allow hydraulic fracturing fluids or other fluids to reach underground drinking water resources.
- Spills of produced water can reach groundwater and surface water resources.
- Disposal practices can release inadequately treated or untreated hydraulic fracturing wastewater to groundwater and surface water resources.
The report definitely provides some targets for future studies, but considering that the EPA is about to fall under the leadership of Scott Pruitt, who as Oklahoma AG had an "unprecedented secretive alliance" with oil and gas companies, and who sued the EPA over an earlier version of this same report … don’t expect this report to lead to much in either the way of future study or sensible regulations.