The U.S. EPA has posted these historical documents to enhance public access to information. These documents do not establish or affect legal rights or obligations. They do not constitute any Agency determination or policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

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Reports and Updates

December 22, 2016

EPA has completed its review of the Wyoming Department of Environmental Quality’s November 7, 2016 Pavillion, Wyoming Area Domestic Water Wells Final Report and Palatability Study. EPA’s letter to WDEQ is linked below.

• EPA December 22, 2016 letter to WDEQ (PDF) (2 pp, 131 K, About PDF)

March 21, 2016
Consistent with the June 20, 2013 announcement, EPA continued to provide input to the state of Wyoming in during their investigation of Pavillion groundwater issues. As part of that input, EPA has provided technical comments to the Wyoming Department of Environmental Quality on their draft Pavillion, Wyoming Area Domestic Water Wells Draft Final Report and Palatability Study. EPA’s letter to WDEQ and the accompanying technical comments are linked below:

• EPA March 18, 2016 letter to WDEQ transmitting comments (PDF)(2 pp, 962 K, About PDF)
• EPA technical comments on WDEQ draft final Report (PDF)(18 pp, 487 K, About PDF)

March 25, 2014
Consistent with the June 20, 2013 announcement, EPA continued to provide input to the state of Wyoming in their ongoing investigation of Pavillion groundwater issues. As part of that input, EPA provided a summary/evaluation of information on gas wellbore integrity and pits for consideration by the state of Wyoming. Documents (all in PDF format) are provided below:

• Pavillion Gas Well Integrity Evaluation (EPA Region 8, July 2013) (28 pp, 1 MB, About PDF)
• Pavillion Oil & Gas Field Pits Evaluation (EPA Region 8, July 2013) (31 pp, 700 K, About PDF)
• Oil & Gas Field Pits Evaluation: Appendices A-B (23 pp, 249 K, About PDF)
• Oil & Gas Field Pits Evaluation: Appendix C (252 pp, 9.9 MB, About PDF)
• Oil & Gas Field Pits Evaluation: Appendix D (848 pp, 16.8 MB, About PDF)
• Oil & Gas Field Pits Evaluation: Appendices E-F (106 pp, 5.2 MB, About PDF)

September 11, 2013
Consistent with a June 20 announcement, EPA announced the discontinuation of the public comment period for the external review of the draft research report, "Investigation of Ground Water Contamination near Pavillion, Wyoming (PDF)" (1 p, 176 K,About PDF). EPA does not plan to finalize or seek peer review of the draft report and will continue to support the State of Wyoming as it investigates water quality in the area.

June 20, 2013
EPA has announced its support for the State of Wyoming in its further investigation of drinking water quality in the rural area east of Pavillion, Wyoming. While EPA stands behind its work and data, the agency recognizes the State of Wyoming’s commitment to further investigation and efforts to provide clean water and does not plan to finalize or seek peer review of its draft Pavillion groundwater report released in December 2011.

The sampling data obtained throughout EPA’s groundwater investigation will be considered in Wyoming’s further investigation, and EPA will have the opportunity to provide input to the State of Wyoming and recommend third-party experts for the State’s consideration. The State intends to conclude its investigation and release a final report by September 30, 2014.

• View the press release
• View the state investigation document (PDF) (6 pp, 369 K, About PDF)

January 11, 2013
EPA extended the public comment period for the draft research report to September 30, 2013. During this time, EPA continued its public outreach activities including meeting with key stakeholders and posting additional technical information on this website. This extension allowed the public additional opportunity to comment on EPA's draft report and the latest round of sampling conducted by EPA and USGS. The Agency incorporated this new data, further stakeholder input, and public comment as it reviewed the status of the Pavillion investigation and considered options for moving forward. View the Federal Register notice announcing the extension of the public comment period (PDF) (2 pp, 203 K, About PDF).

November 6, 2012
EPA  updated and corrected the well completion schematics for Monitoring Wells 01 and 02 based on a detailed review of the drillers logs and field notes. View the updated schematics here:

• Monitoring Well 01 Completion Schematic (PDF)(1 pg, 202 K, About PDF)
• Monitoring Well 02 Completion Schematic (PDF)(1 pg, 193 K, About PDF)

October 16, 2012
EPAextended the public comment period on the Draft Report until January 15, 2013. View the Federal Register Notice announcing the extension of the public comment period.

October 10, 2012
EPA released the methodology and results for samples collected during April 2012. Click here for more information.

September 26, 2012
The U.S. Geological Survey has released data from samples taken from a Pavillion area monitoring well earlier this year. USGS conducted this sampling at the request of the State of Wyoming and in coordination with EPA.

• Groundwater-Quality and Quality-Control Data for Two Monitoring Wells near Pavillion, Wyoming, April and May 2012
• Sampling and Analysis Plan for the Characterization of Groundwater Quality in Two Monitoring Wells near Pavillion, Wyoming

June 2012: Update on sampling activity
EPA, in cooperation with the U.S. Geological Survey, the Tribes, and the State of Wyoming, re-sampled two monitoring wells the Agency installed in the Pavillion area in the summer of 2010. EPA also collected samples from four private and one public water supply well. Sample results are posted on this web page. These data were made available for public comment.

March 8, 2012: EPA extending public comment period and delaying peer review to consider additional sampling
EPA and the State of Wyoming recognized the value of further sampling of the deep monitoring wells drilled for the Agency’s ground water study in Pavillion, Wyoming. EPA partnered with the U.S. Geological Survey (USGS), the State, and the Tribes to complete this sampling.

To ensure that the results of this next phase of testing were available for the proposed peer review process, EPA delayed convening the peer review panel on the Pavillion Draft Report until a report containing the USGS data are publicly available. In addition, EPA is extended the public comment period on the Draft Report through October 2012 to provide additional time for the public to review and comment on the new data. View Federal Register Notice announcing public comment period (PDF)(5 pp, 75 K, About PDF)

View the full joint statement from EPA Administrator Lisa Jackson, Governor Matt Mead and the Northern Arapaho and Eastern Shoshone Tribes.

February 8, 2012: The public comment period on the Draft Peer Review Charge opened on February 8; the comment period has closed. View public comments on the Draft Peer Review Charge that were received during the public comment period:

• Comment from Lloyd Hetrick
• Comment from John Corra
• Comment from David Stewart
• Comment from Nancy Tujague

January 31, 2012: 622 files were added to the Site Documents page. The files include additional analytical data and QA documentation.

• Op-ed from EPA Regional Administrator Jim Martin in the Casper Star-Tribune (1/22)
• Letter from EPA Administrator Lisa Jackson to Governor Matt Mead (1/19)

January 18, 2012: EPA invited the public to nominate scientific experts to be considered as peer reviewers of a draft report on the Pavillion ground water investigation. Nominations will be accepted through February 17. Details can be found in the Federal Register notice (PDF).(2 pp, 156 K, About PDF)

View more information on the peer review process

December 14, 2011: EPA released a draft report outlining findings from the Pavillion, Wyoming groundwater investigation for public comment and independent scientific peer review. The draft report was available for public comment through September 2013.

November 9, 2011: EPA released the latest data from Pavillion-area domestic and monitoring wells at a public meeting on November 9, 2011. We are sharing this data with the community, Encana, the state, tribes and federal partners as part of an ongoing process to develop sound science about contamination in the aquifer used by Pavillion residents for drinking water.

Public Documents and Presentations

• Methods, Graphics, and Data Tables Handout, November 8, 2011
• 2010-2011 Sampling Summary of Results and Next Steps Presentation, November 9, 2011
• Workgroup Meeting Presentation, November 30, 2011