Delineation of Brine Contamination in and near the East Poplar Oil Field, Fort Peck Indian Reservation, Northeastern Montana

Brine is a byproduct of crude oil production. Handling and disposal of brine during the last 50 years in the East Poplar oil field has resulted in contamination of not only the shallow Quaternary aquifers, but also the Poplar River. Previous investigations have documented and partially delineated the extent of brine contamination in the East Poplar oil field during the early 1990s. In the 10 years since the last USGS study ended, the extent of contamination has changed and may have grown larger. Brine contamination has not only affected the water quality from privately owned wells in and near the East Poplar oil field, but also the city of Poplar’s public water-supply wells.