On December 8, 2011, the U.S. Environmental Protection Agency (EPA) issued a draft report on its investigation of groundwater contamination near the town of Pavillion, Wyoming. This CRS report provides a synopsis of the statutory authority for EPA's investigation under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), a summary of the primary findings in the EPA Draft Report, and a brief discussion of issues raised subsequent to the release of the draft report by proponents and opponents of the use of hydraulic fracturing for natural gas development. EPA indicated that it would defer to the state of Wyoming to assume the lead role in investigating drinking water quality in the area, and that the continuing role of EPA would focus on providing technical support and input to the state. EPA also stated that its approach indicates that gas production activities have likely enhanced the migration of natural gas in the aquifer and the migration of gas to domestic wells in the area. Stakeholder Responses to the EPA Draft Report

Because the EPA Draft Report linked groundwater contamination in Wyoming to activities related to hydraulic fracturing, it had raised concerns about hydraulic fracturing practices in general. Some stakeholders took issue with some of the findings in the draft report. Various organizations representing private business interests within the oil and gas industry questioned the scientific validity of EPA's contention that "the explanation best fitting the data for the deep monitoring wells is that constituents associated with hydraulic fracturing have been released into the Wind River drinking water aquifer at depths above the current production zone." In contrast, some environmental organizations cited EPA's findings in calling for more stringent regulation of hydraulic fracturing. Some stakeholders also commissioned independent assessments of EPA's Draft Report and released their respective assessments in May 2012. An assessment commissioned by an industry organization disagreed with EPA's findings, whereas an assessment commissioned by four environmental organizations supported the agency's findings. The IPAA-commissioned report agreed with the EPA Draft Report's conclusion that surface pits were the source of shallow groundwater contamination in the area of investigation, but disagreed that constituents associated with hydraulic fracturing were released into the Wind River drinking water supply (Conclusion 2 of the EPA Draft Report), and that hydraulic fracturing has led to enhanced migration of natural gas to groundwater used for domestic water supply (Conclusion 3 of the EPA Draft Report). On January 20, 2012, 11 members of the Senate Environment and Public Works Committee sent a letter to EPA Administrator Lisa Jackson asking that the EPA investigation be considered a "highly influential scientific assessment and that any related, generated report is subject to the most rigorous, independent, and thorough external peer review process." In the House, the Subcommittee on Energy and Environment of the Committee on Science, Space, and Technology held a hearing on February 1, 2012, to examine EPA's findings and stakeholder concerns. On March 8, 2012, EPA had announced its decision to collect additional samples from the deep monitoring wells in response to concerns about the scientific validity of the agency's findings. The USGS report contains raw data results only from EPA well MW01. In an initial news report, an EPA spokesperson stated that the USGS data are "generally consistent" with the earlier EPA draft report findings. A spokesman from Encana stated that there was nothing surprising in the USGS results, based on a preliminary examination of the data. EPA did not appear to conclude that there was a definitive link to a release from the production wells, nor to the constituents found in the domestic wells in the shallower portion of the aquifer. Now that EPA has decided not to finalize its report, nor to subject it to independent scientific peer review, whatever additional actions may be taken at the Pavillion site would appear to depend on the outcome of the investigation of the state of Wyoming and what role EPA may play in a supporting capacity.
On December 8, 2011, the U.S. Environmental Protection Agency (EPA) issued a draft report on its investigation of groundwater contamination near the town of Pavillion, Wyoming. EPA had initiated the investigation under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) in response to citizen complaints in 2008 about domestic well water quality. On June 20, 2013, EPA announced that it would not finalize the report but would defer to the state of Wyoming to assume the lead in investigating drinking water quality in Pavillion. The EPA draft report indicated that certain constituents in groundwater are consistent with some of the constituents used in natural gas well operations, including the process of hydraulic fracturing. EPA claimed that its approach to the investigation best supports the explanation that different compounds associated with hydraulic fracturing have contaminated the aquifer used for domestic water supply in the Pavillion area. EPA also stated that its approach indicates that gas production activities have likely enhanced the migration of natural gas in the aquifer. EPA did not appear to conclude that there was a definitive link to a release from the production wells, nor to the constituents found in domestic wells in shallower parts of the aquifer.
Because the draft report linked groundwater contamination in Wyoming to activities related to hydraulic fracturing, it had raised concerns about hydraulic fracturing practices in general. Some stakeholders took issue with some of the findings in the draft report. They questioned the scientific validity of EPA's contention that "the explanation best fitting the data for the deep monitoring wells is that constituents associated with hydraulic fracturing have been released into the Wind River drinking water aquifer at depths above the current production zone." In contrast, some environmental organizations cited EPA's findings in calling for more stringent regulation of hydraulic fracturing. Stakeholder groups commissioned independent assessments of EPA's draft report and released their respective assessments in May 2012. An assessment commissioned by an industry organization disagreed with EPA's findings, whereas an assessment commissioned by four environmental organizations supported the agency's findings.
EPA's draft report also has received attention within Congress. On January 20, 2012, 11 members of the Senate Environment and Public Works Committee sent a letter to EPA Administrator Lisa Jackson asking that the EPA investigation be considered a "highly influential scientific assessment and that any related, generated report is subject to the most rigorous, independent, and thorough external peer review process." In the House, the Subcommittee on Energy and Environment of the Committee on Science, Space, and Technology held a hearing on February 1, 2012, to examine EPA's findings. Concerns about the status of EPA's report and the scientific validity of its findings have continued into the 113th Congress.
In response to concerns about the adequacy of the original data, EPA worked with the U.S. Geological Survey and the state of Wyoming to collect additional samples from two deep monitoring wells installed by EPA. On September 26, 2012, the USGS released two reports regarding their sampling program for the two wells. The USGS provided raw data from only one well because the second well did not yield enough water to collect representative samples. A news report cited an EPA spokesperson stating that the USGS sampling results were generally consistent with findings from the earlier EPA draft report. An industry spokesperson stated that there was nothing surprising in the USGS results, based on a preliminary examination of the data. Now that EPA has decided not to finalize its report, whatever additional actions may be taken at the Pavillion site would appear to depend on the outcome of the investigation of the state of Wyoming and what continuing role EPA may play in a supporting capacity.