Environmental groups say the White House is siding with the natural gas industry over its own Environmental Protection Agency following a report this week from the EPA's internal watchdog about an investigation of potential groundwater contamination from hydraulic fracturing, or fracking.

EPA's inspector general said the agency was within bounds when it withdrew an emergency order protecting residents from contaminated drinking water in Parker County, Texas, but said that "issues remain," noting that the "overall risk faced by current and future area residents has not been determined."

That, combined with the EPA walking away from two other high-profile water pollution cases, has left some environmental groups believing that President Obama is quashing the EPA probes to serve other policy goals to which fracking-spurred development of natural gas is central, such as climate change and manufacturing.

"I think [the EPA has] been bludgeoned with a sledgehammer. The EPA, by all indications, wanted to do their job," said Sharon Wilson, a Texas-based activist with Earthworks, an environmental group focused on energy development.

The dissatisfaction from environmental groups underscores a complicated relationship with the Obama administration. Although largely supportive of the president's climate change goals, some organizations reject the president's reliance on switching from coal to natural gas to curb greenhouse gas emissions.

Shale gas accounted for 10.3 trillion cubic feet of production in 2012, according to the U.S. Energy Information Administration, jumping from about 2.9 trillion cubic feet in 2008 — the year associated with the start of the shale boom. The U.S. consumed roughly 25.5 trillion cubic feet of natural gas in 2012.

Although natural gas has half the carbon intensity of coal, environmentalists are concerned about the effect that leaks of potent, heat-trapping methane from fracking has on global warming. They also say the Obama administration has turned a blind eye to the potential pollution problem.

"It seems that Obama has been eager to support natural gas without having all the questions answered first," Wilson said.

Fracking is a drilling method that involves injecting a cocktail of water, sand and chemicals into tight rock formations to access hard-to-reach hydrocarbons. It is credited with driving the domestic energy boom. The oil and gas industry say it's safe, but environmental and public health groups fear it contaminates groundwater.

The inspector general report said the EPA was justified in issuing a 2010 emergency order to natural gas firm Range Resources after it found elevated levels of methane and benzene, a carcinogen, in residential water. The EPA's regional office concluded through testing that Range Resources' natural gas well was the most likely cause of contamination, and that Justice Department and EPA officials had "enough evidence and support to enforce the order."

The EPA, however, withdrew the order after an agreement with Range Resources.

The report comes after the EPA dropped two high-profile cases in Pavillion, Wyo., which in 2011 was the first time a federal agency acknowledged a potential link between fracking and groundwater pollution, and Dimock, Pa., made famous in the Oscar-nominated documentary "Gasland."

Amy Mall, senior policy analyst with the Natural Resources Defense Council, said that amounted to an unsettling "pattern."

"If the staff in the region, career staff, thinks these are cases that warrant investigations and the EPA is pulling back, I think the question needs to be asked" about whether the White House is pushing aside investigations, Mall said.

EPA spokeswoman Alisha Johnson noted that the report concluded that both the issuance of the emergency order and its withdrawal were valid.

"The report also finds that EPA’s exercise of discretion to resolve the matter – including an agreement that Range conduct sampling in the area – was consistent with all applicable rules and policies. EPA agrees with these conclusions," she said. "EPA will continue to share any additional sampling data and relevant information provided by Range and other parties with the Texas Railroad Commission, which is the lead state agency charged with overseeing oil and gas-related activities in Texas."

Mall said, however, that the inspector general report "makes us wonder whether [the administration is] 100 percent committed to the science and committed to ensuring the integrity of the science."

The EPA, which is conducting a long-term study on the potential link between fracking and water pollution, said it withdrew the Texas order to shift from a focus on legal issues to science. The agency will not issue another emergency order for the well site, it said.

The inspector general report focused largely on why the EPA withdrew its emergency order against Range Resources.

It said the EPA did so because of concerns about the legal costs and noted that EPA felt the contamination threat was reduced because the affected residents had begun buying water from another source. On top of that, Range Resources agreed to conduct its own testing and provide samples.

But the inspector general found the driller's attempts inadequate and recommended the EPA re-evaluate the data, to which the agency agreed.

Some Republicans, however, say the inspector general report didn't go far enough, as it didn't assess the conduct of EPA staff who handled the Parker County case.

The inquiry, requested by Sen. James Inhofe, R-Okla., came after agency emails showed former regional administrator Al Armendariz, who now works with the Sierra Club, had emailed anti-fracking activists about the investigation. Armendariz resigned in April 2012 amid GOP pressure following later comments that he would "crucify" companies that run afoul of environmental laws.

Referring to Armendariz, a Senate GOP aide said EPA's internal watchdog should have investigated whether "ideologues" are pulling the strings at regional offices.

"We feel like this report didn't cover that sufficiently," the aide said.