— Those living in Johnstown and other Conemaugh Valley communities in 1889 were well aware of the threat represented by the huge impoundment of water behind the South Fork Dam.
A wet spring, leading up to a record-setting overnight storm May 30 had rivers out over their banks in many areas, including downtown Johnstown.
“At 7 a.m., the rivers were still in their channels although the lower end of Main Street from Walnut to the Point was under water,” Nathan Daniel Shappee wrote in his 1940 doctoral dissertation. “Residents in the flooded area were busily engaged in removing their furniture in boats and wagons.”
Both the Cambria Iron Co.’s lower works and the Gautier plant closed for the day.
At the South Fork Fishing and Hunting Club, manager F.J. Unger had crews cutting a trench around the southwestern end of the dam to prevent over-topping and relieve pressure on the already leaking structure.
In their study published last year, Pitt-Johnstown researchers Uldis Kaktins, Carrie Davis Todd, Stephanie Wojno and Neil Coleman say it appears the crews were trying to reopen a spillway that had been removed by the club. Reports of water first over-topping the dam at the southwestern end provides more evidence of the auxiliary spillway’s existence, they say.
Wrong for 124 years?
Water reached the top of the dam around 11:30 a.m., eroding the earthen mound and saturating the substandard clay the UPJ geology experts contend was used during the club’s reconstruction of the dam.
The new research has also shed light on the actual failure of the dam, which the authors estimate came around 2:50 p.m. on May 31, 1889. They note that eyewitnesses gave a range of times from 2:45 to 3:15 p.m., with 3:10-3:15 being the most widely accepted.
But that isn’t possible, Kaktins said, noting that the clock at the South Fork signal tower was stopped at 3:08 p.m. when it was knocked off its foundation.