A new study from researchers at the University of Nevada, Reno, finds elevated mercury levels in wood ducks along the Carson River, downstream from Nevada’s historic Comstock Lode. In the 1800s, miners used mercury to extract gold and silver from crushed rock. Much of that toxic metal washed into nearby waterways, where it settled into sediments along riverbanks and floodplains. … While the research focused on the Carson River watershed, the implications extend beyond northern Nevada. Historic mining shaped watersheds across the Mountain West, including parts of Colorado, Idaho and Montana. Many of those rivers still contain legacy contamination from gold and silver extraction.