We all want easy answers. And often times the harder the question, the easier we want the answer to be.

Increased natural gas use, for example, can help decrease U.S. greenhouse gas emissions as it has a lower carbon content compared to coal or oil. Natural gas also can help transition our energy mix to more renewable energy sources. This is because properly designed, gas-fired generation can respond quickly to pick up the slack if the wind suddenly dies or clouds unexpectedly roll in. But, these benefits mean nothing if the communities where gas is produced suffer air and water pollution, or if methane – a powerful global warming pollutant that is the primary ingredient in natural gas – is allowed to leak into the atmosphere unchecked.

We all should be worried about global warming and the role that sloppy oil and gas production and distribution practices contribute to the problem. But communities where oil and gas development is taking place are also worried about how oil and gas drilling is impacting their water supplies. This is a key issue and one aspect of the groundwater contamination concerns, rightfully gaining attention in these communities, is how and where toxic wastewater is disposed of that is produced along with oil and gas. But here, too, the answers don’t come easy.

The basic regulatory framework

More than 25 percent of the country’s approximately 700,000 injection wells handle produced water from oil and gas operations. The quantities are huge – at least 2 billion gallons per day. And this fluid is not harmless. Produced water from oil and gas operations is usually much saltier than sea water (it will kill plants and can ruin soil) and is often laced with heavy metals and radionuclides that are naturally present in the formation being drilled. In addition, this produced water can contain hundreds of toxic chemicals – anti-freeze to name just one example. The current standard practice for addressing this potential environmental hazard is through injection of the water into geologic formations suited to permanent disposal.

The 1974 Safe Drinking Water Act gave the EPA oversight of underground wells injected with chemical-laden fluids for disposal and other purposes. In most cases, EPA delegates the authority to state agencies, but in some states, such as Pennsylvania, EPA regulates the wells itself.

EPA’s Underground Injection Control (UIC) program generally has received high marks. In fact, many environmental advocates believe it is important to expand the program to include hydraulic fracturing of oil and gas wells, which was largely excluded from UIC regulation by the “Halliburton loophole” passed by Congress in 2005.

Challenges with existing methods

For all its high marks, the UIC program also has its problems. For starters, it is uncertain whether all states are following EPA’s definition of “Underground Source of Drinking Water”– the water that is supposed to be protected.

Leaks sometimes occur from storage tanks at UIC wells.

Other challenges include: inadequate investigations in some jurisdictions of the surrounding disposal area to make sure no unplugged wells or natural faults allow wastewater to migrate into water supplies; not always assuring that pressures during injection are held low enough to avoid breaks in caprock that protect aquifers; failing to make sure that injection is always limited to permitted intervals; and responding to the increasing number of small and medium size earthquakes that are linked to injections.

Underfunding of regulatory programs compounds the problem, making it harder to provide the public with assurance that their water quality is protected from oil and gas development.

Wastewater Recycling: Buyer Beware

Recycling oil and gas wastewater for reuse in hydraulic fracturing operations is on the rise. The challenge, however, is that recycling requires storage and transport, and almost always requires some sort of treatment. How new residual waste streams are dealt with that carry far more toxic and concentrated substances than the water treated is a major environmental concern as companies jump on the recycling trend.Growing interest in the Appalachian Basin to treat oil and gas wastewater and discharge it into surface streams has heightened attention on these matters. Right now, these discharges are subject to EPA’s National Pollutant Discharge Elimination System (NPDES), but as EPA recently noted in its Preliminary 2014 Effluent Guidelines Program Plan, “current regulations may not provide adequate controls for oil and gas extraction wastewaters.”

Recycling wastewater does reduce the need for freshwater and reduce the volumes that need to be disposed, but it can make disposal much more challenging – particularly when we don’t know enough about the treatment process and resulting waste products.

Diligent oversight needed

Permanent storage using underground injection wells remains by far the most common disposal method. At this point, it also appears to be the least risky, not to be confused with “unrisky”.

But there are things that can be done right now to help us begin to minimize these risks, such as updating requirements for the installation and maintenance of pits and tanks, assessing risks posed by new forms of transport and adopting appropriate risk controls, and doubling down on efforts to identify and remediate leaks and spills.

Bottom-line: none of this is simple. And questions about management of this produced water from drilling operations further demonstrates why we need to stay vigilant in better understanding the environmental impacts of oil and gas development. Having worked most of my career on these issues, it is clear to me that incremental but near-constant improvements are essential to minimize risks and protect communities.

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Originally Published on December 12, 2014

The Energy Exchange Blog is a forum where EDF‘s energy experts discuss how to accelerate the transition to a clean, low-carbon energy economy. Follow them on Twitter here: @EDFEnergyEX