CLEVELAND—The ailing Cuyahoga river, bloated with industrial pollution, erupted into flames reaching as high as a five story building on June 22, 1969. The river, one of several heavily polluted waterways that feed Lake Erie, had caught fire at least a dozen times over the course of a decade, the horror of which helped spark the nascent U.S. environmental movement, leading to the enactment of landmark legislation like the 1972 Clean Water Act.