"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-plume migration is toward the nearby City of Poplar, which, at present, relies on the shallow Quaternary aquifers as its sole source of water."