The Johnstown Flood: the Worst Dam Failure in U.S. History

March 2, 2007 — -- The collapse of the Kaloko Dam was a tragedy, but by no means an isolated one. There have been a number of fatal dam breaks in the United Statest.

But by far the most famous dam failure, and indeed one of the worst disasters in U.S. history, was the Johnstown flood of 1889. It is also a story with striking similarities to that of the Kaloko Dam collapse.

In the late 1800s, Johnstown was a thriving -- if somewhat modest -- community in western Pennsylvania. Just 14 miles away, however, was the South Fork Hunting & Fishing Club, an exclusive enclave whose members included Andrew Carnegie, Henry Frick and Andrew Mellon. In 1879 the club had restored an abandoned earthen dam and created Lake Conemaugh, a pleasure lake used for sailing and ice boating, which they stocked with expensive game fish.

Some people in Johnstown feared the dam wasn't safe. Daniel Morrell, one of Johnstown's most prominent civic leaders even had the dam inspected, and wrote to the club pointing out major flaws -- including the lack of an adequate water outlet -- but his concerns were summarily dismissed.

In May 1889 there were several days of extraordinarily heavy rains. By May 31, management at the club realized the dam was in danger of giving way, but there was little they could do. As Morrell had pointed out, the water outlet at the base of the dam had been filled in years before, and the emergency spillway, which had been reduced in size and covered with screens to prevent expensive fish from escaping, was now clogged with debris.

Messages were sent to Johnstown warning that the dam might give, but after years of false alarms, the messages were ignored. The water began to top the dam, and eventually it gave way.