In Alaska’s Salmon River, leached metals reach levels that are toxic for aquatic life

The Salmon River, in remote northwestern Alaska, has long been a symbol of the region’s untrammeled, wild beauty.

Beginning in 2019, the river turned orange and yellow, reminiscent of acidic runoff from mining waste. (…) The river and many of its tributaries are now laced with toxic metals, leached from thawing permafrost, at levels that can harm aquatic life, scientists report today in the Proceedings of the National Academy of Sciences.