Companies must continue to monitor groundwater contamination and supply alternate water source if needed
The U.S. Environmental Protection Agency (EPA) has reached an agreement with three oil production companies operating on the Fort Peck Reservation in Montana requiring the companies to address groundwater contamination threatening the city of Poplar’s public water supply system.
The agreement with Murphy Exploration & Production Co., Pioneer Natural Resources USA Inc., and SGH Enterprises Inc. (Samson) requires the companies to continue to monitor the city of Poplar’s public water supply monthly and provide treatment or an alternate drinking water source if water quality degrades to a point that presents a public health risk. These requirements will remain in effect until a new and safe source of drinking water is secured by the city. The agreement also requires the companies to pay $320,000 to the city to reimburse costs related to water infrastructure and relocating water wells.
The administrative order, issued under the Safe Drinking Water Act, replaces an emergency order issued by EPA in December 2010. The companies previously had appealed the order in federal court, which referred the case to a mediation process. The new agreement is a result of that process.
Over the past several years, groundwater sampling results indicate that contamination related to production in the East Poplar oilfield has reached the city of Poplar’s water supply.
The source of this contamination is produced brine, highly saline wastewater containing trace metals, inorganic salt concentrations and volatile organic compounds. EPA estimates that more than 40 million gal of brine entered the drinking water aquifer over the span of five decades. The direction of the brine plume movement is generally toward the city of Poplar.
While treated water from the city of Poplar’s water system is currently safe to drink, monthly samples collected by the oil companies indicate an upward trend in total dissolved solids, chloride and sodium. Under the new order, EPA and the companies have identified trigger values that will allow time for action before the public water supply presents any health risks. If these values are met, the companies will take immediate steps to secure additional treatment or provide alternative water to ensure contamination levels are below human health thresholds.
A long-term alternative water source for the city of Poplar currently is being developed through construction of a pipeline from the Missouri River. The city also has plans to relocate its water wells to secure a backup supply. These efforts are expected to be completed as early as this year.
EPA, the state of Montana, the Fort Peck Tribes, the U.S. Geological Survey and other agencies have been aware of groundwater contamination in the East Poplar oil field for several decades. Various studies have been done in the area, and the nature, extent and movement of the plumes are relatively well known. EPA has addressed past contamination through four Safe Drinking Water Act orders issued to production companies between 1999 and 2004. Murphy, Pioneer and Samson are, directly or through corporate acquisition, historic oil producers in the East Poplar oil field.
Poplar is the seat of the Fort Peck Assiniboine and Sioux Tribes. The Poplar-area public water system, the Fort Peck Tribe Water Resource, serves approximately 3,000 people, including tribal and non-tribal households.