On December 8, 2011, the EPA issued a draft report which concluded that oil and gas activity likely caused contamination of water wells near Pavillion, Wyoming (see Oil & Gas Law Brief, December 12, 2011).  Encana, which operates numerous natural gas wells in that area, criticized the EPA's draft report, stating that the EPA's data do not support its conclusions.  Since then, Encana has issued a statement that explains some of the reasons that it disputes the EPA's conclusions.

Encana explains that the EPA did not find any impact from oil and gas activity when it tested samples from the area's domestic water wells, which typically are drilled to depths of less than 300 feet.  "The EPA's reported results of all four phases of its domestic water well tests do not exceed federal or state drinking water quality standards for any constituent relating to oil and gas development." 

The EPA also collected samples from two much deeper monitoring wells (to depths between 783 and 981 feet) that the Agency drilled into a shallow natural gas reservoir.  Encana states that the water samples EPA collected from those monitoring wells contained "components of natural gas,"  but that is "an entirely expected result" given that natural gas is found naturally at the depths to which the monitoring wells were drilled.  Indeed, reports Encana, natural gas is found in commercial quantities at depths as shallow as 1100 feet, only slightly deeper than the EPA's monitoring wells, and no cap rock exists in the area to prevent some of that natural gas from migrating naturally to shallower depths.

Pavillion is a shallow natural gas field.  Naturally occurring methane (natural gas) exists throughout the subsurface geology, filling channel sands from millions of years ago.  This natural gas is commonly known to have been present in groundwater from domestic water wells for decades, dating back to well before any natural gas drilling started."

Encana's statement declared that, "Natural gas developers didn't put the natural gas at the bottom of the EPA's deep monitoring wells, nature did."

Encana also states that the EPA's lab analyses contain "unacceptable inconsistency."  Further, Encana states that additional problems are demonstrated by the analyses of the EPA's quality control (blank) samples.  Such blank samples do not contain water collected from domestic wells or monitoring wells, and instead contain ultra pure water that is put into supposedly clean sample collection containers.  The blanks are analyzed as a test to verify that the Agency is not inadvertently causing contamination by the use of unclean collection containers or improper sampling technique.  When analyzed, the blank samples should not contain contaminants.  But Encana states that man-made chemicals were found in many of the EPA's blanks, indicating a problem in the EPA's methodology.

Encana also expressed disappointment that the EPA published its draft report "before subjecting it to qualified, third-party, scientific verification."

Encana stated that the Pavillion area also had other water quality problems that existed before any natural gas drilling began in the area.

As far back as the 1880s, U.S. Geological Survey (USGS) reported about poor water quality in Pavillion.  More recent USGS reports dating back to 1959 have documented Pavillion water as unsatisfactory for domestic use due to high concentrations of naturally occurring sulfate, total dissolved solids and pH levels which commonly exceeded state and federal drinking water standards."

Other sources of information on Pavillion include the EPA's Region 8.  It has a webpage with information regarding the Agency's Pavillion investigation and links to various resources.  Also, the Wyoming Oil and Gas Conservation Commission has a "Pavillion Working Group" page with links to several documents.  In addition, the Petroleum Association of Wyoming has issued a statement about the EPA's draft report regarding Pavillion.