The Environmental Protection Agency (EPA) issued measures for using diesel in hydraulic fracturing, setting standards it said could be adopted by states to govern a process that has spurred the boom in natural gas production.

While drillers say diesel has mostly been phased out of the process called fracing, they sought to block the EPA’s criteria, saying it could lead to greater federal oversight and delays in getting permits.

The agency, in a statement Feb. 11, said the standards rely on state and industry best practices, and are part of its efforts to ensure “responsible development” of gas trapped in shale. Among other measures, the EPA is recommending baseline and follow-up testing of water sources near drilling sites.

States “updating regulations for hydraulic fracturing may find the recommendations useful in improving the protection of underground sources of drinking water and public health more broadly,” the agency said in a document explaining the new standards.

In 2005, Congress exempted fracing, in which water, sand and chemicals are shot underground to free gas or oil trapped in underground rock formations, from the requirements of the Safe Drinking Water Act. That exemption was labeled the “Halliburton loophole” by health advocates, referring to Halliburton Co., the largest provider of fracing services, led by Richard Cheney before he was elected vice president in 2000.

The law specified that the EPA retained oversight of fracing if diesel was among ingredients being used, and environmental groups say drillers add the substance to fluids they inject to crack rock and free trapped gas, without applying for the necessary permits.

Diesel is typically used when the underground rock or clay has a tendency to absorb water, according to a report by Democrats on the House Energy and Commerce Committee. That report is outdated, and companies are no longer using diesel, according to industry groups.