Both Andrew and Thomas Carnegie had been members of the South Fork Fishing and Hunting Club , a highly exclusive wealthy businessman 's club which operated a mountaintop retreat overlooking Lake Conemaugh , one of the largest man-made lakes of the day . Lake Conemaugh was formed by the construction of the South Fork Dam in 1853 , but had been drained and abandoned prior to its purchase by the South Fork organization . The club , which formed in 1879 , maintained the South Fork Dam and refilled the reservoir . Andrew and Thomas built a cottage near the clubhouse , and often stayed there . The South Fork Dam failed on May 31 , 1889 , resulting in the disastrous Johnstown Flood
Johnstown Flood
Johnstown Flood
Thomas M. Carnegie