Except for the big ones such as Boulder Dam, hardly anyone pays much attention to dams, and few are even aware of the struggles that might have gone on to build these structures. Dams just sit there doing their jobs year after year in a decidedly unglamorous way. But every day, dams fight a battle against time and the elements. Usually, the dam wins, but once in a while, it doesn’t.

Then people really notice.


The South Fork Dam today, showing the breech

Disaster Area: The South Fork Dam

Unless you live nearby, you probably have never heard of the South Fork Dam in Pennsylvania. And physically, there’s not much reason, you should. South Fork is an earth dam, and it’s downright puny compared to Boulder Dam and many others. Today, in fact, the dam doesn’t even hold any water; it’s just a long mound of earth. On May 31, 1889, however, the South Fork dam breached, unleashing a hellish torrent of water and debris on an unsuspecting town downstream; a place called Johnstown.

Johnstown was a steel mill town, home of the Cambria Iron Works. Situated in a narrow valley on the Little Conemaugh River, the town was 14 miles downstream from the South Fork Dam and directly in the path of any flood. When the dam breached during record heavy rains, there was little to stop the water that was released, a flow that equaled the flow of the Mississippi at one point.

But why would the dam have failed in the first place?

The South Fork Dam was built as part of a cross state canal system, but became less needed as railroads took over most hauling duties. The state sold the dam and Lake Conemaugh to the Pennsylvania Railroad. Finally, a group of wealthy Pittsburgh businessmen led by Henry Clay Frick and Benjamin Rush purchased the dam and the lake to start the South Fork Hunting and Fishing Club, a getaway for the elite of the area. That the lake was dangerous was easy to see. The dam was 450 feet in elevation above Johnstown, assuring any water released woulfd move quickly downstream, and Lake Conemaugh was estimated to hold 20 million tons of water. The new owners were reluctant to spend any money on dam maintenance unless absolutely necessary and were not the sort of men who liked to be told what to do, so maintenance was minimal.

One of the safety features of the original dam was a series of three cast iron discharge pipes that could be used to release water from the dam if it was building up to dangerous levels. A previous owner, however, had removed the pipes and sold them for scrap. Some accounts claim that the club members removed the pipes, while at least one source claims the deteriorated pipes were left in place, but had caps welded on to them. Given the difficulty of welding cast iron, this seems unlikely. Whatever happened and whoever was responsible, the dam now had no device to control or lower the water level if needed.

As bad as this action was, the club members proceeded to make things worse. In order to widen the carriage road across the top of the dam, they lowered the crest. This also meant that water would start topping the dam sooner. The dam featured an emergency spillway just below the crest as a means of releasing water before it overflowed. This was vital because once water starts to flow over the crest of an earth dam, it will erode a path down the face of the dam until the dam fails. The problem with the spillway was that it sometimes allowed the fish to escape, and since the members had paid good money to have the lake stocked, this had to be corrected. The solution was to put up screening in front of the spillway to keep the fish in the lake. The screening, however, caught debris during storms, thus clogging and causing the water to back up faster.

And so the stage was set for the Johnstown Flood.

For days water pounded down on the area, overflowing steams and saturating the soil. The water behind the dam rose higher and leaks began to appear. Men attempted to patch the leaks, but the water kept rising with no way to relieve it until it finally burst through the dam and thundered down the valley of the Little Conemaugh heading for Johnstown. Normally, water suddenly released from a dam will start to lose force and depth as it spreads out along its path. The flood water from the South Fork Dam, however, was flowing down a steep and narrow valley. Still, with fourteen miles to travel, it should have lost some of its force and depth, but about a third of the way to Johnstown, it was once again partially dammed up, this time behind the Conemaugh Viaduct crossing its path. The debris clogged the opening and the water piled up behind the viaduct until the structure gave way, releasing a wall of water and debris with renewed power.


Johnstown Main Street after flood

Fifty-seven minutes after the dam collapsed, the wave hit Johnstown carrying houses, trees, railroad cars, bodies, farm animals, and miles of barbed wire from another Cambria plant upstream. The flood once again damned up, this time behind another railroad bridge in Johnstown, sending another flood wave back along the river and then back to Johnstown like a tide running in and out. This bridge held, and a sea of debris piled up behind it. The debris caught fire and burned for three days, killing many who had barely escaped the flood itself.


Debris at railroad bridge

A total of 2,209 people dies in the disaster, a third of whom were unidentifiable. Among the dead were 99 entire families, including 396  children.

Within a week, crews of local men had rebuilt the Conemaugh Viaduct and restored rail service to Pittsburgh so that relief supplies could be brought in. The citizens faced the horror with courage and determination and were building temporary housing, a hospital and a morgue within hours. Clara Barton arrived and set up the first Red Cross relief effort.

A series of lawsuits against the owners of the South Fork dam went nowhere. The disaster was found to have been an act of God. Some of the South Fork members contributed to the relief efforts, including Andrew Carneige, who contributed a library, among other things. The library is now the Johnstown Flood Museum.

The remains of the dam still stand in silent witness. It was never rebuilt.