Beginning in the 1960s, mining companies began to build coal waste dams--also called "sludge dams" or "slurry impoundments"--to filter solid wastes from streams near mine sites. The Buffalo Creek dam, in Logan County, West Virginia, was built by the Pittston coal company as a series of three impoundments, holding a total of 130 million gallons of sludge.

Early on February 26, 1972, after several days’ rain, the impoundments began to collapse. At 6:00am, Dam #3 (the farthest upstream) fell. Two hours later, all three dams had foundered, and by 8:05am, the first town beneath the dams was hit by a rolling wall of slurry, water, and debris. By the end of the day, sixteen communities had been destroyed. 125 people were confirmed killed, 1,100 injured, and 4,000 left homeless. Seven people were never found.