Johnstown Pennsylvania was founded in 1800, along the banks of the Stony Creek and the Little Conemaugh, where the two waterways combine to form the Conemaugh River. Miles downstream from the drainage basin formed by the Allegheny plateau, the town is hemmed in on both sides by the high, steep hills of the Conemaugh Valley and the Allegheny Mountains. A plaque at the scenic overlook on Rt. 56, four miles outside of Johnstown, describes this gorge as the deepest river gap east of the Rockies.
The South Fork Dam was built 14 miles upstream by the Commonwealth of Pennsylvania, forming Lake Conemaugh and providing a feeder for the state’s network of canals. Welsh and German immigrants came to the area as the completion of the Main Line Canal led to the construction of the Pennsylvania Railroad and the Cambria Iron Works. The area flourished as multiple villages and factories were built along the banks of the Conemaugh, crowding the river basin forming the narrow floor of the valley.
The Commonwealth sold the dam and the lake to private interests when rail began to supersede the canal as the primary mode of transport. The property changed hands a couple times more: one owner removing the three iron pipes that formed a spillway and selling them for scrap, the next lowering the dam to build a road and installing a fish grate. These were the wealthy industrialists who turned the mountain lake into an exclusive private retreat for themselves and their families, calling it the South Fork Fishing and Hunting Club.
The rain that began to fall on the 29th was unprecedented, at times falling at the rate of 6 to 10 inches per hour. Elias Unger, then president of the South Fork Fishing and Hunting Club, awoke on the morning of the 31st to see the water just about to overtop the dam. He and several others worked throughout the morning to unclog the fish screen at the spillway. By 1:30 that afternoon they were forced to take to the high ground and wait.
The dam was 72 feet high, 931 feet long, holding back an estimated 4.8 billion gallons of water. The average flow of water over Niagara Falls is 64,750 cubic feet per second. When the South Fork Dam let go it released 642,726,934 cubic feet of water down the valley. The lake was emptied in 45 minutes.
The Village of South Fork was first to be hit, and then the town of Mineral Point, about a mile below the viaduct. When the flood receded, there was nothing left of the town but bare rock.
By the time the flood reached East Conemaugh, it had picked up so much debris that one survivor said it looked like a “huge hill, rolling over and over”. People living and dead cascaded down the valley with trees and homes and animals and debris of every kind. Next the flood hit the Cambria Iron Works and the Gautier Wire Works in Woodvale, sweeping train cars, boilers and miles of barbed wire up in the deluge.
Locomotive engineer John Hess got ahead of the approaching flood for a time, as he tied down the train whistle and raced backward down the line trying to warn as many as possible. His warning saved many people before the flood caught up with him and tossed his locomotive aside. Hess would survive the flood, though many of the passengers stranded in rail cars, did not.
Traveling at 40 miles per hour, the 60′ wall of water and debris hit Johnstown 57 minutes after the dam broke. Some residents had managed to scramble to high ground, but most were caught by surprise by the flood waters.
An enormous stone railroad bridge at the edge of Johnstown caught and held tons of barbed wire entangled debris on its upstream side. Perversely, the debris caught fire and the fire became an inferno that burned for three days, killing 80 people. After the flood waters receded, the field of debris at the bridge covered 30 acres and reached 70 feet high.
When it was over, 2,209 were dead. 99 entire families had ceased to exist, including 396 children. 124 women and 198 men were widowed, 98 children orphaned. 777 people, over 1/3rd of the dead, were never identified. Their remains are buried in the “Plot of the Unknown” in Grandview Cemetery in Westmont.
Property damage exceeded $17 million, over $425 million in today’s dollars.