The transboundary watersheds of Canada and the United States contribute valuable economic, social, and ecological benefits to their respective regions. Due to concern for negative potential impacts from Canadian mining operations, Congress directed the U.S. Geological Survey (USGS) in 2018 to begin an ongoing water-quality study to establish baseline conditions in these rivers and monitor changes in water quality and ecosystem health over time. In 2019, USGS Science Centers in Alaska, Washington, Idaho, and Montana began water quality assessments in nine transboundary watersheds. In southeast Alaska, five rivers (from north to south) are included in this monitoring program: the Alsek, Taku, Stikine, and Unuk rivers, as well as the Salmon River, which is located near Hyder, Alaska. USGS stream gages collect continuous measurements of water-quality parameters, including temperature, pH, and dissolved oxygen. In addition to these continuous data, annual sample collection visits are conducted, which comprise discrete water-quality samples, whole body fish, liver and fillet tissue, sediment, algae, and moss from within the bankfull channel. Water and solids samples are sent to national USGS laboratories in Denver, Colorado and Moffett Field, California, for selected metals analysis, including copper (Cu), cadmium (Cd), mercury (Hg), lead (Pb), selenium (Se), and zinc (Zn). Approximately 90 sediment samples have been collected since 2019. Sediment concentrations of metals from samples at each of the five Alaska sites from the last 6 years and their observed trends over time will be presented. In addition, a comparison between sites will be presented and discussed.