"The U.S. Environmental Protection Agency (EPA) is not adequately monitoring more than 172,000 wells used to enhance oil and gas drilling and dispose of drilling wastewater, according to a July 28 report by the Government Accountability Office (GAO). The report, based on two years of research, identified several significant problems with EPA's program to protect groundwater from drilling chemicals and wastes. Since millions get their drinking water from groundwater, these problems raise significant questions about how effectively and consistently we are protecting public drinking water.
The Safe Drinking Water Act gives EPA authority to regulate underground injections of hazardous and non-hazardous fluids in order to protect drinking water from contamination. EPA's Underground Injection Control (UIC) class II program, as it is formally known, sets standards for fluid wells, covering well construction, operation, monitoring and testing, completion, and more. Thirty-nine states manage their own programs that incorporate EPA-required safeguards, while EPA regional offices oversee wells in the remaining states.
Class II wells include three types of wells – enhanced recovery wells, where drilling fluids are pumped into existing wells in order to increase production, disposal wells, where drilling waste is disposed of through underground injection, and storage wells, which contain liquid petroleum products. Of these, enhanced recovery wells are the most common and make up around 80 percent of all class II wells."