The U.S. Environmental Protection Agency said Thursday it will develop standards for wastewater discharges produced by the use of hydraulic fracturing at natural gas extraction sites. â¿¿No comprehensive set of national standards exists at this time for the disposal of wastewater discharged from natural gas extraction activities,â¿ the agency said in a statement. It said it has reviewed evidence of "elevated levels of pollutants entering surface waters as a result of inadequate treatment" of wastewater from hydraulic fracturing. â¿¿Over the coming months EPA will begin the process of developing a proposed standard with the input of stakeholders -- including industry and public health groups,â¿ it said. > DBJ REPORT: Fracking aids oil and gas extraction, raises environmental eyebrows. > DBJ PHOTO GALLERY on fracking. Hydraulic fracturing, or â¿¿fracking,â¿ involves the injection of water, sand and chemicals underground to aid in the extraction of natural gas from underground formations. The process has been increasingly common in Colorado in recent years. Energy industry experts say fracking is critical to Coloradoâ¿¿s $24 billion-a-year oil and gas industry. But fracking has become controÂversial as environmental groups, homeowners and others have raised worries that the process could contaminate groundwater supplies, and that the accumulation of chemicals it uses could harm the environment. â¿¿Currently, wastewater associated with shale gas extraction is prohibited from being directly discharged to waterways and other waters of the U.S.,â¿ EPA said. â¿¿While some of the wastewater from shale gas extraction is reused or re-injected, a significant amount still requires disposal. As a result, some shale gas wastewater is transported to treatment plants, many of which are not properly equipped to treat this type of wastewater.â¿ The agency said it will set standards that must be met by fracking wastewater before it goes to a treatment facility.