Shale development using hydraulic fracturing involves pumping a mixture of sand, water, and chemicals into deep rock formations at high pressure in order to release natural gas or oil. A single well may use 3–6 million gallons of water, although usage can vary widely depending on the well and the specific shale formation. 1 The majority of the water usage takes place in the development and production stages of the project, when drilling and hydraulic fracturing require fluids for cooling, lubricating, maintaining pressure in the well, and fracturing the shale.
Water used in these operations can be sourced from surface waters such as rivers, lakes and streams, from municipal water supplies, or from underground aquifers. Overuse of an area’s groundwater can cause land subsidence, a reduction in surface waters, and, due to the interconnected nature of the water cycle, long-term unsustainability of water supplies. In an effort to reduce their use of fresh water supplies, operators also draw on municipal wastewater, recycled water, or brackish water. 2
In the United States, the states are primarily responsible for the regulation and permitting of withdrawals from surface and groundwater. According to a study of 31 states by Resources for the Future, most states require permits for water withdrawals, although some only require them for withdrawals above a certain threshold. 3 Others require disclosure of withdrawals, with the exception of Kentucky, which exempts the oil and gas industry from water allocation regulations. Pennsylvania and West Virginia require companies to submit a water management plan that includes an impact analysis of the planned withdrawals. 4
Although the water needed for drilling the wells and fracturing operations may represent a fraction of the overall water resources available, the timing of withdrawals over the short time period that operations occur—as well as cumulative withdrawals for multiple sites—can bring the industry into competition with other local uses, including municipal, agricultural, and recreational. Due to the location of the oil and gas reserves, shale energy operations are often concentrated in small communities with limited resources to handle any stress on their water supplies. If the area is experiencing drought, which is the case for over half the areas of shale development in North America, withdrawals can exacerbate stressed conditions. 5
After hydraulic fracturing has taken place, a portion of the injected water—ranging from 30% to 70% of the original 6—returns to the surface, while the remaining portion is trapped in the shale formation. This produced water often contains naturally occurring chemicals such as salts, heavy metals, and naturally occurring radioactive materials (NORM) from the rock formation. (For information on water quality issues, see Stage 3.)
There are several methods for managing well site wastewater. It can be processed on the well pad site or transported to a waste treatment facility. If the water is treated to remove pollutants, it can ultimately be returned to surface waters, where it re-enters the water cycle. Some companies recycle the wastewater, treating it and mixing it with fresh water before reusing it in their operations or providing it for other industrial or agricultural uses. Wastewater can also be injected into underground disposal wells, where it is stored between layers of impermeable rock thousands of feet from usable groundwater resources. From a water availability perspective, disposing of the water in this manner effectively removes it from the global water cycle.
In June 2015, the EPA published a draft report on the potential impact of hydraulic fracturing on drinking water resources. The final report will include the effects of each stage of hydraulic fracturing on the quantity and quality of drinking water. 7 The cycles under consideration in this report include water acquisition, chemical mixing, well injection, produced water, and wastewater treatment and waste disposal (see Figure 6 below).
- U.S. Government Accountability Office, “Oil and Gas: Information on Shale Resources, Development, and Environmental and Public Health Risks” (September 2012). ↩
- Water whose salt content falls between that of fresh and seawater. ↩
- Richardson, Nathan, Madeline Gottlieb, Alan Krupnick, and Hannah Wiseman, The State of State Shale Gas Regulation, Resources for the Future (June 2013). ↩
- Nathan Richardson et al., The State of State Shale Gas Regulation, 40–41. ↩
- Monika Freyman, Hydraulic Fracturing & Water Stress: Water Demand by the Numbers (Ceres, February 2014), 6. ↩
- Ground Water Protection Council and ALL Consulting, “Modern Shale Gas in the United States: A Primer,” Prepared for U.S. Department of Energy Office of Fossil Energy and the National Energy Technology Laboratory, April 2009, 66. ↩
- Given that the draft report is currently under review by the EPA’s Science Advisory Board and is marked as not for citation, we have refrained from citing the study’s preliminary conclusions on water quantity in this version of the guidebook. ↩