The Johnstown Flood (1889)

At the time it happened, the Johnstown Flood was the worst natural disaster in the history of the United States.  It was the biggest news story since the assassination of President Lincoln, 24 years earlier.  And it is a lesson of tragic proportion that dams, which do much good, are also tremendously dangerous.

            The spring of 1889 had been a wet one in western Pennsylvania.  Johnstown, a town of 30,000 residents a bit east of Pittsburgh, and the surrounding area had experienced unusually high amounts of rainfall. Rain had been falling for several days leading up to the disaster that occurred on May 31. The Conemaugh River, which flowed through Johnstown, ran swollen and angry. 

The Schultz family home after the flood; all 7 members of the family were in the house and lived (photo by Ran Showley)

            Fourteen miles upstream from Johnstown, a reservoir sat on the South Fork of the Conemaugh River.  The reservoir, called Lake Conemaugh, had been impounded by the South Fork Dam, an earthen dam built in 1853.  The lake was built to provide water to feed the many canals that transported canal boats throughout Pennsylvania and New York (learn more about the Erie Canal here).  The lake covered 425 acres and was 50 feet deep at the dam. Both the dam and the reservoir were the largest in the U.S. at the time. But as the canal system was replaced for transportation by railroads, the dam and lake became obsolete and fell into poor condition.

            A group of wealthy residents of Pittsburgh, including Andrew Carnegie and Andrew Mellon, bought the lake and dam in 1879 as a private fishing and recreational resort for themselves and their families.  They made repairs to keep the dam intact, but the work was shoddy, performed by unqualified laborers.  They also modified the dam in two ways.  First, they lowered the dam by two feet to allow a wider road across the top.  Second, they fitted the spillway with screens to keep the fish they stocked into the lake from escaping.

Destruction in downtown Johnstown (photo by National Park Service)

            These changes proved catastrophic.  When the heavy rainfall raised the water far above usual levels, large amounts of debris washed from the shorelines to the dam, clogging the screened spillway.  The water built higher and began to flow over the top of the lowered dam.  Spillways exist at dams to prevent water from ever going over the top of a dam, because the downstream side will erode under the rush of water coming over the top. 

            Conditions continued to worsen throughout the day of May 31.  By mid-afternoon, warnings were being issued that the dam was in peril, but the news was slow getting downstream to Johnstown.  At 3:15 PM, the dam burst.  Twenty million tons of water blew through the dam, forming a wall of water 40 feet high, raging downstream at 40 miles per hour.

the main street of Johnstown after the flood (photo by E. Benjamin Andrews)

            The wall hit Johnstown about 4 PM, with virtually no warning.  The devastation was massive.  Four square miles of downtown Johnstown were completely destroyed, including 1600 homes.  At total of 2,209 people died; 99 entire families were wiped out.  A railroad bridge through town became clogged with debris that grew to a 30-acre pile; it started on fire, killing 75 people who had sought refuge there from the raging waters.

            The scale of the response matched the scale of the tragedy.  The Red Cross, which had begun during the Civil War and was led by Clara Barton, came to Johnstown and stayed for months, building shelters and caring for the injured and homeless.  This effort was the beginning of the ongoing work of the Red Cross when disasters strike across the world.  Lawsuits were filed against the wealthy dam owners for negligence, but no judgments were ever made because of the difficulty of proving fault.

            The story of the Johnstown Flood teaches several lessons.  First, dams are essential features of modern infrastructure. The U.S. has more than 87,000 dams, and the worldwide total is many times that.  Dams provide stable water supplies, prevent flooding, and generate power.

            Second, however, is that dams are dangerous.    If they are not built properly and maintained properly, they will fail. Hundreds of dam failures occur annually, although most are small and few take human life.  The cause is almost always water flowing over the top of the dam, just as was the case in the Johnstown Flood (read about the world’s biggest dam disaster here).

            And, third, although dams, particularly large dams, are not popular in the United States now (the golden era of dam building in the U.S. was from 1950 to 1980), they are very popular throughout the world.  New dams continue to be built across most of the developing world, where the needs for water and power outweigh the environmental concerns that drive American decision-making.


Degen, Paula and Carl.  2013.  The Johnstown Flood of 1889.  Eastern National, 64 pages.  The Johnstown Flood.  Available at:  Accessed May 7, 2019.

Johnstown Flood Museum.  Statistics about the great disaster.  Available at:  Accessed May 7, 2019.

National Park Service.  Johnstown Flood National Memorial.  Available at:  Accessed May 7, 2019.

This Month in Conservation

February 1
Afobaka Dam and Operation Gwamba (1964)
February 2
Groundhog Day
February 3
Spencer Fullerton Baird, First U.S. Fish Commissioner, Born (1823)
February 3
George Adamson, African Lion Rehabilitator, Born (1906)
February 4
Congress Overrides President Reagan’s Veto of Clean Water Act (1987)
February 5
National Wildlife Federation Created (1936)
February 6
Colin Murdoch, Inventor of the Tranquilizer Gun, Born (1929)
February 7
Karl August Mobius, Ecology Pioneer, Born (1825)
February 8
President Johnson Addresses Congress about Conservation (1965)
February 8
Lisa Perez Jackson, Environmental Leader, Born (1982)
February 9
U.S. Fish Commission Created (1871)
February 10
Frances Moore Lappe, author of Diet for a Small Planet, born (1944)
February 11
International Day of Women and Girls in Science
February 12
Judge Boldt Affirms Native American Fishing Rights (1974)
February 13
Thomas Malthus Born (1766)
February 14
Nature’s Faithful Lovers
February 15
Complete Human Genome Published (2001)
February 16
Kyoto Protocol, Controlling Greenhouse-Gas Emissions, Begins (2005)
February 16
Alvaro Ugalde, Father of Costa Rica’s National Parks, Born (1946)
February 17
Sombath Somphone, Laotian Environmentalist, Born (1952)
February 17
R. A. Fischer, Statistician, Born (1890)
February 18
World Pangolin Day
February 18
Julia Butterfly Hill, Tree-Sitter, Born (1974)
February 19
Lincoln Boyhood National Memorial Established (1962)
February 20
Ansel Adams, Nature Photographer, Born (1902)
February 21
Carolina Parakeet Goes Extinct (1918)
February 22
Nile Day
February 23
Italy’s Largest Inland Oil Spill (2010)
February 24
Joseph Banks, British Botanist, Born (1743)
February 25
First Federal Timber Act Passed (1799)
February 26
Four National Parks Established (1917-1929)
February 27
International Polar Bear Day
February 28
Watson and Crick Discover The Double Helix (1953)
February 29
Nature’s Famous Leapers
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