Correction appended.

Wyoming's congressional delegation is splitting from fellow Republican Sen. James Inhofe on his criticism of a U.S. EPA investigation of water contamination in their state.

Sens. Mike Enzi and John Barrasso and Rep. Cynthia Lummis have taken a wait-and-see approach to the agency's Superfund probe in the community of Pavillion, Wyo.

But Inhofe, the Oklahoma Republican who serves as the Senate GOP's point man on environmental issues, has accused EPA's Denver-based investigators of withholding information from Congress and creating a "cloud of uncertainty" for Enzi and Barrasso's constituents in Pavillion. A high-ranking EPA official in Denver has apologized to Inhofe for lack of communication.

Enzi, Barrasso and Lummis have each issued vague statements saying that residents deserved answers. Barrasso indicated he has "worked with the EPA." Enzi emphasized that EPA determined the town's drinking water is contaminated "without identifying the source."

But many people in Pavillion blame oil and gas drilling. Last year, EPA researchers were reported to have found that some of the contaminated wells contain a chemical used in the hydraulic fracturing process for natural gas.

"It starts to finger-point stronger and stronger to the source being somehow related to the gas development, including, but not necessarily conclusively, hydraulic fracturing itself," Nathan Wiser, an EPA scientist and hydraulic fracturing expert who oversees enforcement for the underground injection control program under the Safe Drinking Water Act in the Rocky Mountain region, told the website ProPublica in a story published in August 2009. The investigation "could certainly have a focusing effect on a lot of folks in the Pavillion area as a nexus between hydraulic fracturing and water contamination."

In addition, Encana Oil & Gas Inc., which has been drilling for gas in the area since 2005, will pay for people to clean up their well water or get drinking water from elsewhere. The company denies responsibility, though, asserting that the hydrocarbon pollution occurred before 2005 and might not have resulted from oil and gas drilling. There has been drilling in the area since the 1960s.

At a meeting in Pavillion late last month, officials from the federal Agency for Toxic Substances and Disease Registry told residents not to drink water from 40 wells in and around the farming and ranching community 135 miles west of Casper. The ATSDR announcement coincided with the release of EPA's latest findings from testing water wells in the Pavillion area.

The testing of 23 water wells in January found low levels of hydrocarbons in 17 residential water wells sampled. Samples from four stock and irrigation wells and two municipal wells did not show hydrocarbon contamination.

EPA has not confirmed or ruled out drilling as a cause of the hydrocarbon contamination. Agency officials expect more testing, including tests from two recently drilled monitoring wells, to answer that question sooner or later.

However, it was not only hydrocarbons that prompted officials to urge residents to treat their well water or find some other source of drinking water. They also blamed high levels of sodium, sulfates and other inorganic compounds.

EPA has found high levels of the inorganic materials in all but one of 41 wells tested since last year.

Inhofe's criticism of EPA revolves around an Aug. 30 call between his staff and EPA officials about the Pavillion situation. The Republican staff of the Environment and Public Works Committee, where Inhofe is the ranking member, has been closely scrutinizing the EPA investigation for months, requesting updates and questioning officials on their conclusions.

In a letter earlier this month to EPA Administrator Lisa Jackson, Inhofe said that EPA officials failed to tell his staff about findings they would announce in Pavillion the next day.

Inhofe wrote that EPA staffers were either "badly misinformed" or "unwilling to divulge" the agency's findings. That, he said, contradicted Jackson's assurance to Congress that she would "recognize the importance of congressional oversight."

That letter prompted a reaction from Jackson and an apology to Inhofe from Jim Martin, EPA's Region 8 administrator in Denver.

"I know that your staff was genuinely surprised when the report was released on Aug. 31, and Region 8's staff could have prevented that surprise with more conscientiousness on their part," Martin wrote. "Please accept my apologies for any ill effects on the part of your office."

The letter was characterized as an interim response, with a more detailed reply to come soon. The interim response did not address Inhofe's complaints that EPA officials on the call indicated they did not know the precise number of wells EPA sampled, the number of affected residents or the extent of the agency's Superfund authority. It also did not address Inhofe's concern that EPA's effort in the Wyoming case is "open-ended."

"That is, when pressed EPA Region 8 staff could provide no sense as to what the next steps would be, with no apparent plan to solve this problem as expeditiously as possible," the senator wrote. "Meanwhile, Pavillion residents are left to wonder about the status of their drinking water. ... The agency should have a specific plan, with a timeline that includes specific milestones and a final end point."

A statement released by Barrasso's office was much less critical of EPA.

"I share Pavillion area residents' concerns about safe drinking water," Barrasso's statement said. "I have worked with the EPA and state officials to determine the quality of the water and how to resolve this issue. I will continue to remain involved and committed to helping folks in and around Pavillion."

A statement released from Enzi's office stressed that he has been closely monitoring the EPA probe.

"The EPA's findings made clear that there is a problem with the water without identifying the source," Enzi's office said. "The most important thing now is to come up with a solution to ensure that the water is safe."

Lummis, the state's lone House member, said, "The safety of our citizens is paramount. I will continue to closely monitor the situation in Pavillion and look forward to the identification of the contaminant, and more importantly, a lasting solution."

Correction: This article has been corrected to state that a quote by EPA scientist Nathan Wiser was published by ProPublica in August 2009, rather than last month. It also clarifies that EPA was reported last year to have found a chemical related to hydraulic fracturing in water supplies. In the results announced this year, the chemicals found were not necessarily consistent with chemicals present that would suggest they were a product of fracturing.