In the summer of 1997, fish in the Chesapeake Bay started turning up dazed, dying, and covered with bleeding lesions. The culprit was a toxic microbe called Pfiesteria piscicida, which was flourishing in the warm, polluted waterways. The one-celled organism, discovered less than a decade earlier, had already killed millions of fish in North Carolina. Now it had spread north — and it was infecting humans, too. More than a dozen watermen exposed to the microbe-laden water fell ill with sores, intestinal woes, and neurocognitive impairments such as confusion and memory loss.

By September, with a national media panic in full gallop, three Maryland rivers were closed to all commercial and recreational use. Seafood sales plummeted, as buyers swore off Maryland crabs and other bay delicacies. An investigative commission blamed the outbreak on high levels of phosphorus, a byproduct of the region’s vast chicken industry.