What Was The Worst Dam Disaster In U.S. History?

Aerial view of Johnstown, Pennsylvania looking across valley, the site of the worst dam disaster

Given America’s reliance on dams to provide the water that we enjoy every day, it only makes sense that an accident would happen a time or two. Several dams have had cracks in their foundation that led to bigger trouble or experienced some other phenomenon in which external damage evolved into a major issue. Of the dam disasters that have occurred in U.S. history, which one was the worst?

The worst dam disaster in U.S. history was the Johnstown Flood on May 31, 1889, in which the South Fork Dam failed to hold its water supply and flooded downstream Johnstown, Pennsylvania. Tragically, over 2,200 lives were lost, and more than $17 million in damage was caused.

A catastrophic event like this goes down in the history books as a tragedy and hopefully gives insights into how another such event can be prevented in the future. Below, you’ll learn the details that led to the Johnstown Flood, how many lives were lost, and what the town has done to rebuild in its aftermath.

America’s Worst Dam Disaster Was the Johnstown Flood

The U.S. has unfortunately experienced a number of dam disasters throughout history, but none have been on the same scale as 1889’s Johnstown Flood in Johnstown, Pennsylvania.

Vintage photo of flood damage near main street

Unfortunately, Johnstown happened to be located in a perilous position 14 miles downstream of the offending dam in question – the South Fork Dam. How the unlucky residents of Johnstown came to suffer the consequences of the South Fork Dam’s failure is a journey riddled with errors that deserve to be delved into.

This event all began when a few members of the business world’s wealthy elites decided they wanted to construct a pleasure lake where they could fish and boat at their own leisure.

You may have heard of some of the people in the group,

  • Andrew Mellon – Banker & industrialist helped found Alcoa, US Steel, and the Gulf Oil Corporation.
  • Andrew Carnegie – Steel magnate and philanthropist. One of the wealthiest men at the time.
  • Henry Frick – Founded the H.C. Frick Coke Company and helped with the founding of the US Steel Corporation.

These business moguls belonged to the tight-knit South Fork Hunting & Fishing Club, and in 1879, they chose to restore a previously forgotten dam to construct the lake mentioned above, known as Lake Conemaugh. The consequences that followed this dam’s restoration would be unfathomable.

The South Fork Dam’s initial construction took place over 15 years between 1838 and 1853 as an earthen dam, or a dam built using compressed layers of earth. Standing at an impressive 72 feet high and stretching over 930 feet in length, the South Fork Dam was abandoned by the state of Pennsylvania and passed between the hands of multiple buyers. It isn’t readily known how much the dam was meant to hold, but at the moment it broke, over 3.5 billion gallons, or 20 million tons, of water flooded out of it.

Vintage photo of camp of Disaster Relief Corps

Johnstown residents voiced their concerns even at the dawn of the dam’s initial restoration. Many were not confident that this new dam met safety regulations or that the men who ordered its construction were qualified to undertake such a task.

These fears were only given more credence when a Johnstown civic leader named Daniel Morrell called for the dam’s inspection and found that the dam did indeed have severe safety problems. But, unfortunately, the men in charge of correcting these issues opted to ignore Morrell’s complaints rather than act.

Johnstown residents’ fears became a reality one fateful day in late May of 1889, when a massive amount of rainfall overloaded the South Fork Dam and caused it to fail. Three significant reasons stand out as being the impetus for the dam’s downfall:

  • The water outlet needed to release excess water had been packed full already.
  • The emergency spillway was not only made inadequately small, so exotic fish couldn’t escape, but was also clogged.
  • Any cracks in the dam had been improperly filled with weak material.

By the time the owners took heed of Morrell’s word and actually noticed that the dam was at risk of failing, it was too late.

Vintage photo of Main Street looking east after flood

Twenty million tons of water flooded into Johnstown as the South Fork Dam failed to hold the rain back, leading to the deaths of 2,209 people. There wasn’t much time for residents to evacuate, given the rushing water, but unfortunately, the warnings that were issued fell upon deaf ears. Johnstown residents had heard that the dam might flood numerous times over the years and thought this was just another instance of the media making a mountain out of a molehill, with no real danger to worry about. As a result, few people chose to leave the town, and tragedy ensued.

On top of the horrifically high death toll, the Johnstown Flood caused over $17 million in damages, which equates to over $500 million today.

Support came in from around the world as people and organizations from other states and countries donated funds to help the town recover. Unfortunately, in a cruel twist of fate, the men responsible for the incident were never brought to justice as they held large amounts of power. However, the whole event did cause the U.S. to revisit liability laws to deter such negligence from being repeated in the future.

Keystone Answers Fun Fact: The severe impact of the Johnstown Flood meant that outside help was required from as many organizations as possible. Among the very first outsiders to show up in Johnstown to offer help was the founder and president of the American Red Cross herself, Clara Barton, who aided the town’s recovery for over five months.

Was Johnstown Rebuilt After the Flood?

After the Johnstown Flood of 1889, the town was rebuilt, and life continued as normally as possible. In a cruel twist of fate, that flood marked the beginning of a series of floods that would plague the town throughout the next century, with the 1977 flood becoming particularly devastating. Johnstown has consistently been rebuilt after each flood through efforts by the townsfolk and officials from both the government and the Red Cross.

The town’s population has heavily fluctuated since the 1889 flood. It reached its peak about 30 years later, in 1920, at an estimated total of over 67,000 residents. This high lasted for roughly 30 more years until it began to steadily decline around 1950. This decrease has persisted ever since, and today, Johnstown’s population is estimated to be a little under 18,000 residents, falling just short of 1889 levels.

Does the South Fork Dam Still Exist?

The South Fork Dam collapsed in the Johnstown Flood under the weight of over 20 million tons of water and has not been rebuilt since. The dam is symbolic today of the severe damage inclement weather can cause and the dangers of careless management.

Remnants of old South Fork Dam overgrown with trees and brush

Structural problems had riddled the South Fork Dam since its construction began in 1838, and each new owner of the dam failed to make the proper adjustments to keep up the dam’s maintenance. All of these errors culminated in the infamous Johnstown Flood, and the South Fork Dam has not been touched since.

Points of Interest

As the site of a tragic historic event, Johnstown has a number of memorials and museums where visitors can learn more about the flood and honor the lives that were lost. The National Park Service has a Johnstown Flood Memorial with lots of informative attractions. The Lake View Visitor Center provides a detailed history of the flood, with an additional wealth of knowledge available at the bookstore.

One of the most remarkable pieces of the National Park Service’s memorial has to be the remnants of the South Fork Dam itself. Visitors can actually walk through parts of the destroyed dam to see for themselves what it looks like today. Those really keen on the idea can even sign up for “A Walk Through the Ruins,” a guided hike that takes visitors up and down the dam and through the breach that caused the Johnstown Flood.

The National Park Service isn’t the only organization that created a memorial for the flood. The Johnstown Area Heritage Association built the Johnstown Flood Museum, which is ideal for anyone wanting to dive deep into the events that led to the flood and the flood’s aftermath.

Top of inclined plane with view of Johnstown, Pennsylvania

While in town, take a ride on the Johnstown Inclined Plane; the trip will take you up Yoder Hill to an elevation of 1,693 feet, up a 70% grade with a perpendicular lift of 502.2 feet. There is a fee to ride it, but the view is spectacular. Also on the hill above the Inclined Plane is a 125-foot flagpole with a beautiful 30’x60′ American flag flying. It is one of the largest free-flying flags in the US.

The Heritage Discovery Center is located in a former brewery and houses exhibits telling the story of the early immigrants to the area, how the steel and coal industry played a part in Johnstown’s past, and the third floor is devoted to Johnstown Children’s Museum. You can visit seven days a week, and active military members get a 20% discount.

In addition, you can go on a walking tour of downtown Johnstown and learn about historic sites, or you can do an online tour now from the comfort of your home!

The Johnstown Flood is Remembered To This Day

The legacy of Johnstown has been largely dictated by the fact that it was the site of the worst dam disaster in U.S. history, but there’s much more to the town than that. Johnstown’s people are resilient and have worked hard over the years to rebuild and construct a new life for themselves and honor those lost in the flood. Take a trip to Johnstown to see how this community has bounced back from this disastrous flood.

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I was born and raised in Pennsylvania; I love to travel, visit new destinations, explore unique locations, and meet great new people. However, sometimes, you don't need to travel far from home to find new adventures, so I decided now was the time to learn more about this great state I call home.