Founded in 1794, Johnstown, Pennsylvania began to prosper with the building of the Pennsylvania Mainline Canal in 1834 and the arrival of the Pennsylvania Railroad and the Cambria Iron Company in the 1850s. There was one small drawback to living in the city. Johnstown had been built on a floodplain at the fork of the Little Conemaugh River and Stony Creek. Because the growing city had increased the runoff from the surrounding hills by stripping them for wood and had narrowed the river banks to gain building space, the heavy annual rains had caused increased flooding in recent years.
The South Fork Dam was built between 1838 and 1853 by the Commonwealth of Pennsylvania to provide water for the operation of the Western Division of the Pennsylvania Mainline Canal between Johnstown and Pittsburgh. Though the dam had been built according to accepted engineering practices, the canal system was obsolete by the time the dam was completed in 1853.
Located some 14 miles east of Johnstown at a point where the South Fork branch of the Little Conemaugh River and several mountain streams converged, the dam created what was, at the time, one of the largest artificial lakes in the nation, more than two miles long and nearly a mile wide in some places. Lake Conemaugh was held by the dam on the side of a mountain, 450 feet higher than Johnstown. The Pennsylvania Railroad Company purchased the entire Mainline works in 1857 and left the dam and the reservoir virtually unattended. In 1862 a break occurred near the discharge pipes, but little damage resulted because the water level was so low. Afterward, the railroad abandoned the dam, and it deteriorated
In 1879 a group of wealthy Pittsburgh industrialists, including such men as Andrew Carnegie and Andrew Mellon, formed the South Fork Fishing and Hunting Club and bought the dam and the reservoir as an exclusive and somewhat secret summer resort. By 1881 the dam had been repaired, without the benefit of an engineer, and the reservoir filled to capacity to form the now nearly three-mile-long Lake Conemaugh. A clubhouse with 47 rooms fronted the lake. From its large porch, members could watch the club’s two steam yachts setting off on excursion trips. A number of club members built large cottages nearby. For the next eight years, the summer resort offered fishing, hunting, boating, and other recreational opportunities for club members.
Over the years, some people worried about the 72-foot-high earthen dam, one of the largest earthen dams in the world, causing one resident to remark:
“No one could see the immense height to which that artificial dam had been built without fearing the tremendous power of the water behind it….”
Others wondered and asked why the dam had not been strengthened, as it certainly had become weak, making Johnstown vulnerable. Daniel J. Morrell, president of Cambria Iron Company, was one of those worried about the dam and made repeated requests that the dam be strengthened. However, Benjamin Ruff, the first president of the South Fork Club, responded by saying: “You and your people are in no danger from our enterprise.”
In the end, nothing was done and by and by, most Johnstown residents talked less and less about it. Others, realizing their continuing vulnerability, called the dam “the sword of Damocles hanging over Johnstown.”
By 1889, Johnstown had grown to a town of 30,000 German and Welsh immigrants, known for the quality of the steel it produced.
On May 30, 1889, after unusually heavy rains hit the area, the citizens of Johnstown were warned three times of a possible impending flood if the dam didn’t hold. But, that had been the case every spring for so many years, that it the supposed threat had become something of a standing joke around town. And wasn’t the dam being maintained by some of the richest and most powerful men in America?
While some people in Johnstown made the usual preparations for flooding, John Parke, the club engineer who was at the South Fork Dam, knew things were more serious. Watching the lake rising an inch every 10 minutes, he knew that once the water ran over the top of the earthen dam, it would cut through it like a knife and the whole thing would go. His workers desperately tried to dig another spillway and increase the height of the dam, but the water was rising too fast. Parke was caught in a painful dilemma. He could cut through the end of the dam, where the pressure was less, so it would give way more slowly and reduce the water’s destructive force. But afterward, how could he prove that the dam would have gone anyway? People would know only that he was the one who destroyed the dam and flooded the valley. He chose not to do it.
On the chilly, wet afternoon of May 31st, the dam started to go at 3:10 p.m.
“The fearful rushing waters opened the gap with such increasing rapidity that soon after the entire lake leaped out… It took but forty minutes to drain that three miles of water.”
— John Parke, South Fork Engineer