Johnstown, Pennsylvania was well known for the high quality of its steel … and the shoddy quality of the South Fork Dam. Rebuilt in 1879 after lying dormant for years, the Dam was a civil engineer's nightmare. The original spillway, built to handle runoff during rainy seasons, was now 20% narrower than it had been in 1862, when a major break had washed away a large section of the dam, forcing the State of Pennsylvania to abandon it. The bridge which allowed access to the posh South Fork Hunting and Fishing Club had iron screens across the runways. These kept the fish from swimming away … and reduced the discharge of water by an estimated 40%. What's more, the "repairs" which had been made to the dam had already begun to leak, and the center embankment, which was supposed to be the highest part of the dam, had settled until it was six inches lower than the rest of the dam. Every spring there was talk that the dam was going to break: by 1889 it had become a standing joke among Johnstown's 30,000 residents.
On May 30, 1889 a storm blew in from Nebraska, bringing with it an estimated 6-10 inches of rain. Throughout the region small creeks overflowed their banks; by the morning of May 31 there was water in the streets of Johnstown. This still brought no particular alarm; Johnstown was built on a plain between the Little Conemaugh and Stony Creek Rivers, and usually saw at least flooding at least once every spring. The people of Johnstown moved their things to the upper stories of their houses and prepared to wait out yet another flash flood, unaware of the devastation to come.
Fourteen miles away, at the South Fork Dam, laborers worked desperately to keep the dam from breaking. During the night the 400-acre lake behind the dam had risen nearly two feet and grown to 450 acres; the iron grates had become clogged with debris and were hampering the runoff. Every minute another 4,000 cubic feet of water built up in the lake, and observers began to notice a pronounced bulge in the dam's center. A trench built to drain some of the water had to be abandoned when the workers struck rock; an earthen embankment built at the top of the dam was soon washed away. By 11:30a.m. water was rushing over the top of the dam.
John G. Parke, the dam's resident engineer rushed off to the telegraph office on horseback, hoping to warn the residents of Johnstown. Ms. Ogle, the telegraph operator, notified every station, even as the flood raced toward her: soon after typing out "this is my last message" she was swept away in the oncoming tide and drowned. As she sent her messages, Parke galloped away on horseback, yelling "Run for your lives! The dam is breaking." Unfortunately, many who saw Parke screaming wild-eyed in the streets assumed he was a lunatic and dismissed his message, assuming that the dam would hold this time as it always had.
At 3:10 p.m. a large section of the dam "moved away," in the word of one eyewitness. The whole lake - over 20 million tons of water - emptied in 45 minutes. A wall of water 60 feet high came barrelling down toward Johnstown at 40 miles an hour. Over 3,000 wooden and brick houses, hotels, factories and churches were levelled in an instant, then joined with trees, rocks, locomotives and other huge chunks of debris in the boiling torrent. When the flood had finally spent itself 2,209 people had died and 27,000 were left homeless.
In the aftermath, most survivors blamed the disaster on the members of the South Fork Fishing and Hunting Club, who had repaired the old dam, raised the lake level, and built cottages and a clubhouse in their secretive retreat in the mountains. The Club was served with several lawsuits by survivors. Ultimately (perhaps unsurprisingly, given that the club counted Pittsburgh magnates Andrew Carnegie and Joseph Mellon among its members), the flood was determined to be an "act of God," magnified by shortcomings in the design of the original dam; the obvious shortcomings in the new construction were not officially blamed for contributing to the disaster. A $3 million surety bond which had supposedly guaranteed the dam's construction was never found, and the South Fork Club was not held liable for any deaths, or for the estimated $17 million in property damages.