For humans, contaminated watersheds can compromise drinking water sources by requiring extensive water treatment or even making some water supplies temporarily unusable.
A tiny, vibrant world thrives along the rocky bottom of most streams. As sunlight filters through the water, mayfly nymphs, no larger than your fingernail, cling to algae-coated cobbles. Their brushlike mouthparts scrape the greenish coating, leaving faint trails as they feed. Six spindly legs anchor them against the current...