15. Johnstown and the South Fork Dam
Johnstown, on the eastern end of the Allegheny Portage Railroad, created a reservoir for the canal’s western division. South Fork Dam, an earthen dam, created an artificial lake, which the residents of the region called Lake Conemaugh. It held approximately 20 million tons of water, reserved to maintain water levels in the canal and aqueduct which connected Johnstown to the Ohio and Monongahela Rivers in Pittsburgh. Like Hollidaysburg, Johnstown boomed with the opening of the portage, its canal basin lined with warehouses, shipping facilities, boatyards and docks. By 1850, with the canal and portage operating at their peak, Johnstown’s population neared 1,300, over three times that when Main Line first opened.
The South Fork Dam was sold to the Pennsylvania Railroad as part of that corporation’s purchase of the Allegheny Portage Railroad in the late 1850s. The Pennsylvania in turn sold the dam and the reservoir to private interests. It became the site of the South Fork Fishing and Yacht Club in 1879. Ten years later, the unmaintained dam failed after a period of heavy rains, releasing the contents of the reservoir to sweep down on Johnstown in the famous flood which killed more than 2,200 people. A stone bridge, built as part of the Allegheny Portage Railroad, briefly withstood the torrent for a time before it too was swept away in the floodwaters.