The South Fork Dam

The South Fork Dam. . You are now standing on what remains of the South Fork Dam. Completed in 1853, the dam was made chiefly of earth. Layers of clay one-foot-thick or less were built up one by one. Each layer was covered with a skim of water, or “puddled,” to help it settle and harden. Five large outlet pipes were installed under the dam to discharge water safely. Slopes were faced with stone. The dam's only inadequacy was its spillway (on the other side) which was too small., Although well-engineered for its time, years of neglect and unsound alterations had made the dam unsafe. By 1889, the water control tower had burned down, and the iron outlet pipes had been removed, making it impossible to control the lake level. Earlier breaches in the dam had been improperly filled with stone, dirt, brush, and even manure. The dam had settled and sagged at the center, inviting a washout. In addition, fish screens had reduced the capacity of the spillway to handle overflow., On May 31, 1889, under the force of rising floodwaters, the dam gave way, creating the gaping hole in front of you. From here the flood wave thundered 14 miles downstream to Johnstown, killing more than 2,200., “The dam itself, or the parts of it which were left standing, showed undoubtedly that it was well and thoroughly built....” , American Society of Civil Engineers, January 15, 1890