USGS hydrologist monitoring water quality and collecting samples at USGS Station15015595 on the Unuk River, Alaska. In 2019, the USGS began studying the baseline water-quality of selected transboundary rivers in Alaska. These studies are designed to characterize current water-quality conditions to facilitate future assessments of potential impacts related to upstream mining activities. (Courtesy/Jamie Pierce, Alaska Science Center)

The owner of the Eskay Creek mine, about 75 air miles east of Wrangell, in British Columbia, is…