The order is unprecedented in Texas, partly because the federal body overstepped the state agency responsible for overseeing gas and oil drilling in the state. The EPA's move could ratchet up a bitter fight between Texas and the EPA that has evolved in the past year from a dispute over environmental issues into a pitched battle over states rights.
EPA regional director Al Armendariz said he issued the order against Range Resources of Fort Worth, Texas, because he felt the Texas Railroad Commission was not responding quickly enough to contamination found in two water wells belonging to Parker County residents in North Texas.
The EPA began inspecting the wells in August after receiving complaints from residents who said the Texas commission and Range Resources had not responded to problems they were having with their drinking water. The EPA inspected the wells with the commission, Armendariz said, and found high levels of explosive methane, as well as other contaminants, including cancer-causing benzene.
"We thought what we found in the homes was alarming," Armendariz told The Associated Press.
Range Resources on Tuesday denied being the source of the contamination.
"We've been working with the Railroad Commission as well as the landowners over the last several months," spokesman Matt Pitzarella said. "We believe that the methane in the water has absolutely no connection to our operations in the area. We provided that information to the Railroad Commission, the landowners and to the EPA."
The Railroad Commission issued a statement saying members of its staff also have not reached conclusions about the source of the contamination. It said Range Resources is cooperating with the commission's investigation and already had agreed last week to conduct more tests, as well as to perform soil gas surveys, monitor gas concentrations, and offer a water supply to affected residents.
"If the data indicates oil field activities are responsible for the gas found in the water well, the (commission) will require assessment, cleanup, and evaluate what fines or penalties may be assessed as necessary," the statement said.
But John Blevins, the director of the EPA's compliance assurance and enforcement division, wrote in a letter Tuesday to Range Resources that the contamination findings present "a potential imminent endangerment to the health of persons using those private drinking water wells."
The EPA gave Range Resources 24 hours to inform the agency in writing that it will comply with the federal order. It then had 48 hours to provide impacted families with clean drinking water and install monitors in the homes to ensure methane gas levels don't rise to explosive levels. The company was given five days to begin a thorough survey of the aquifer to determine if other wells and families also could be impacted by contamination.
Range Resources has been using new technologies that make it possible to extract once out-of-reach natural gas reserves. Horizontal drilling, along with hydraulic fracturing, or "fracking," make it possible for drillers to permeate once impenetrable geologic formations called shale. The companies pump high volumes of water and chemicals at great pressure into the well bore to permeate the rock, and there have been complaints in some places - especially in Pennsylvania - that underground aquifers have been contaminated in the process.
In November, Pittsburgh became the first city in gas-rich Pennsylvania to after city council members, citing health and environmental concerns, unanimously approved the measure.
This is the first such suspicion in Texas, Armendariz said.
As "60 Minutes" reported in November, fracking and the new drilling techniques have made vast quantities of natural gas available to America's energy companies, creating "an American energy renaissance," in the words of correspondent Lesley Stahl.
One energy company executive told "60 Minutes" that the U.S. had at least two times as much natural gas reserves - locked up in layers of shale - than Saudi Arabia has oil. But as the contentious debate in Pennsylvania and now Texas shows, exploring for energy comes with inherent safety risks.
"60 Minutes": Pros and Cons of Shale Gas Drilling
"60 Minutes" Extra: Meet the "Shaleionaires"
"60 Minutes" Extra: Shale Gas Drilling Horror Story
Pittsburgh Bans Natural Gas Drilling
Natural Gas "Fracking" Debate Draws Hundreds
"Fracking" Draws Concern Over Water Supplies
The families in Parker County have not been identified, but Armendariz said they had been using the wells for years and never had issues until Range began drilling nearby in April 2009. One of the greatest fears is of explosion, he said.
The EPA issued the emergency order under the Safe Drinking Water Act. Texas Railroad commissioner Michael L. Williams called it "Washington politics of the worst kind."
"The EPA's act is nothing more than grandstanding in an effort to interject the federal government into Texas business," he said.