The marker is one of three placed on front of Johnstown City Hall at the flood level of 21'. The marker reads:
High Water (underlined)
21'
May 31, 1889"The Johnstown Flood (locally, the Great Flood of 1889) occurred on Friday, May 31, 1889, after the catastrophic failure of the South Fork Dam, located on the south fork of the Little Conemaugh River, 14 miles (23 km) upstream of the town of Johnstown, Pennsylvania, United States. The dam ruptured after several days of extremely heavy rainfall, releasing 14.55 million cubic meters of water. With a volumetric flow rate that temporarily equaled the average flow rate of the Mississippi River, the flood killed 2,209 people and accounted for $17 million of damage (about $534 million in 2022 money).
The American Red Cross, led by Clara Barton and with fifty volunteers, undertook a major disaster relief effort. Support for victims came from all over the U.S. and eighteen foreign countries. After the flood, survivors suffered a series of legal defeats in their attempts to recover damages from the dam's owners. This led to American law changing from a fault-based regime to one of strict liability.
The city of Johnstown, Pennsylvania, was founded in 1800 by Swiss immigrant Joseph Johns (anglicized from "Schantz") where the Stonycreek and Little Conemaugh rivers joined to form the Conemaugh River. It began to prosper with the building of the Pennsylvania Main Line Canal in 1836 and the construction of the Pennsylvania Railroad and the Cambria Iron Works in the 1850s. By 1889, Johnstown's industries had attracted numerous Welsh and German immigrants. With a population of 30,000, it was a growing industrial community known for the quality of its steel.
The high, steep hills of the narrow Conemaugh Valley and the Allegheny Mountains to the east kept the development of Johnstown close to the riverfront areas. The valley had large amounts of runoff from rain and snowfall. The area surrounding the city is prone to flooding due to its location on the rivers, whose upstream watersheds include an extensive drainage basin of the Allegheny plateau. Adding to these factors, slag from the iron furnaces of the steel mills was dumped along the river to create more land for building. Developers' artificial narrowing of the riverbed to maximize early industries left the city even more flood prone. The Conemaugh River, immediately downstream of Johnstown, is hemmed in by steep mountainsides for about 10 miles (16 km). A roadside plaque alongside Pennsylvania Route 56, which follows this river, proclaims that this stretch of valley is the deepest river gorge in North America east of the Rocky Mountains.
High above the city, the Commonwealth of Pennsylvania built the South Fork Dam between 1838 and 1853 as part of a cross-state canal system, the Main Line of Public Works. Johnstown was the eastern terminus of the Western Division Canal, supplied with water by Lake Conemaugh, the reservoir behind the dam. As railroads superseded canal barge transport, the Commonwealth abandoned the canal and sold it to the Pennsylvania Railroad. The dam and lake were part of the purchase, and the railroad sold them to private interests.
Remains of South Fork Dam showing construction details of the dam, as it appeared in 1980
Henry Clay Frick led a group of Pittsburgh speculators, including Benjamin Ruff, to purchase the abandoned reservoir, modify it, and convert it into a private resort lake for their wealthy associates. Many were connected through business and social links to Carnegie Steel. Development included lowering the dam to make its top wide enough to hold a road and putting a fish screen in the spillway. Workers lowered the dam, which had been 72 feet high, by 3 feet. These alterations are thought to have increased the vulnerability of the dam. Moreover, a system of relief pipes and valves, a feature of the original dam which had previously been sold off for scrap, was not replaced, so the club had no way of lowering the water level in the lake in case of an emergency.
The Pittsburgh speculators built cottages and a clubhouse to create the South Fork Fishing and Hunting Club, an exclusive and private mountain retreat. Membership grew to include more than fifty wealthy steel, coal, and railroad industrialists. Lake Conemaugh at the club's site was 450 feet (140 m) in elevation above Johnstown. The lake was about 2 miles (3.2 km) long, about 1 mile (1.6 km) wide, and 60 feet (18 m) deep near the dam. The dam was 72 feet (22 m) high and 931 feet (284 m) long."
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