Existing comment:
Building the Dam:
In 1853, the State of Pennsylvania completed the South Fork Dam to provide water for the state canal system.
The original earthen dam had been well built: (1) The packed-down or puddled earth made it watertight. (2) The large and unobstructed spillway allowed for a substantial runoff of water. (3) A control tower and (4) discharge pipes regulated the water level.
The dam was 72 feet high, 931 feet long, and originally 10 feet wide across the top. The width of the dam at its base was 270 feet.
The spillway was 70 feet wide and the bottom of the spillway was 10 feet below the top of the dam.
The top of the dam was 450 feet higher than the city of Johnstown 14 miles away.
The dam failed the first time in 1862. The Pennsylvania Railroad had neglected the dam after purchasing it in 1857 and five years later the dam gave way.
The flood frightened the people of Johnstown, but caused little damage. The lake was not full, the discharge pipes released water before the break, the lake took hours to empty, and the creeks below the dam were low.
By 1881, the South Fork Fishing and Hunting Club had purchased the site and repaired the dam to make a summer resort.
The repaired dam had many flaws: (1) The earth was not puddled and leaks had been poorly repaired. (2) The spillway obstructed by a bridge and fish screens. (3) The control tower had burned, (4) discharge pipes had been removed, and the lake was filled to a depth of 65 to 70 feet. (5) The dam was lowered to widen the road. (6) The dam sagged in the middle where the break had been repaired.
The photograph to the right shows the rebuilt dam. Notice the treeless section in the middle where the first break had been repaired.
The repaired dam was, in fact, lower than the original dam, but it held much more water. The water level could not be regulated and the spillway was only 7 or 8 feet below the top of the dam. |