Fish-killing algae blooms have become a growing problem on Lake Erie, and the summer of 2017 was particularly bad. A research plane caught this bright green bloom that August, looming near the lake’s western shore. High-flying, high-tech cameras detect different types of algae, while researchers on the water collect samples, backing up the camera’s readings and giving water engineers timely data for treatment strategies. (A boat wake is visible at bottom center.) The blooms — which thrive in sunshine, warm water and still air — typically feed on fertilizer runoff, but scientists don’t know why only some algal blooms, like this one, produce toxins that are fatal to fish.
[This story originally appeared in print as "Toxic Green Wave."]