glyphosate

Abbie Fentress Swanson/Harvest Public Media

Eleven miles northeast of Centralia, Mo., five U.S. Geological Survey scientists don waders and bright reflective life jackets to wade into Goodwater Creek. Plenty of fish live in the stream’s murky slow-moving waters, along with snakes, crayfish, mussels and snapping turtles. On this overcast morning, the team collects water samples and checks submerged cages of fathead minnows for eggs.