Following months of testing samples from drinking water wells in the Pavillion, WY, area near a natural gas drilling site, the U.S. Environmental Protection Agency (EPA) this week said results indicate the "presence of hydrocarbons and other chemical compounds in the groundwater," which is a "drinking water concern."

Last year the EPA said at least three contaminated water wells near Pavillion contained a hydraulic fracturing chemical used by natural gas drillers (see Daily GPI, Aug. 28, 2009). Officials began testing the area's water wells early in 2009 after landowners complained about water contamination. The agency found petroleum hydrocarbons in at least 17 drinking water wells, but the recommendations this week are within an area that includes 20 drinking water wells.

EPA said the number of drinking water wells contaminated could increase.

Martin Hestmark, EPA's assistant regional administrator for Region 8, said last week "it became clear to us that based on the information we gathered" that Pavillion residents should not continue to drink the area water. "We understand the gravity of that statement. We understand what it means to families of this community."

Encana Corp. began drilling in the area in 2005, and the company contends that the pollution preceded its entry there. Five years ago subsidiary Encana Oil & Gas USA enrolled several already contaminated drilling pits into a state voluntary remediation program. According to the Wyoming Department of Environmental Quality, pollution from at least three of those pits had entered the same water zone that several residents tap for drinking water.

Encana agreed to fund a third party to treat or provide an alternate source of drinking water in a cooperative agreement with EPA.

EPA's 2009 preliminary report did not reach a conclusion about the cause of the water contamination, but officials said at the time that "oil and gas drilling may be a source." The report issued on Monday also did not place blame on any one source: EPA said it had not made "any conclusions about the sources of the chemical compounds found in the drinking water wells."

The federal agency said it "is working closely with various government partners and Encana Corp., the primary gas operator in the area, to ensure that affected residents receive water and to address potential sources." Included are plans to secure access to alternate water sources, as well as to evaluate potential long-term solutions such as water treatment systems and infrastructure.

The U.S. Department of Health and Human Services' Agency for Toxic Substances and Disease Registry (ATSDR) analyzed EPA's data and recommended that affected well owners take "several precautionary steps," which include using alternate sources of water for drinking and cooking.

"EPA will work as long as necessary to ensure that Pavillion residents have safe water," said EPA Regional Administrator Jim Martin. "While our investigation continues, EPA has secured commitments from our partners to identify alternate sources of water for affected homes and to evaluate long-term solutions."

EPA's sampling detected several petroleum hydrocarbons, including benzene and methane, in wells and in groundwater. Low levels of petroleum compounds were found in 17 of 19 drinking water wells sampled.

Sample results also confirmed that nearby shallow groundwater is contaminated with "high levels"of petroleum compounds. "There is uncertainty regarding the potential for this contaminated shallow groundwater to migrate to the drinking water aquifer," officials said.

In addition, federal authorities found several inorganic constituents including sodium and sulfates in drinking and groundwater wells that were tested. However, concentrations of these compounds and metals "were generally within ranges identified in previous studies."

In the past week EPA and ATSDR officials have met privately with individual residents to provide health information and recommendations based on well-specific sampling results. Affected well owners were told to take several precautionary health measures that include using alternate sources of water for drinking and cooking, and, for homes affected by methane gas in wells, ventilating rooms while showering.

ATSDR's analysis of sample results did not find health concerns related to inhalation exposure to chemicals while showering or using evaporative coolers.

EPA and its partners plan to work on the details of agreements over the next several weeks and consult with the community to ensure actions taken to secure safe water meet local needs.

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