Hydraulic fracturing, or “fracking,” releases oil and gas captured in rock formations and makes them easier to collect by injecting fluids—often a mixture of water, sand and various chemicals—into the ground at high pressures, which forms cracks in the rock. The New York Times reported last year that in 2009 there were almost double the number of active natural gas wells in the U.S. than in 1990, and that fracking was used in around 90 percent of them.

The advent of its widespread use in the oil and gas industry, particularly with regard to free natural gas from shale formations, has been both hailed as the solution to the country’s energy needs and vilified as a dangerous threat to the environment and public health. However, federal regulation of fracking is sparse. The public isn’t happy about it: 65 percent of respondents in a March Bloomberg poll said there needs to be more regulation of fracking.