CS5B - Concurrent Session 05B: Frazzled – The 1972 Frazil Ice Failure of Keshena Falls Dam

In the spring of 1972, the turbulent, rain swollen waters of the Wolf River cascaded over the granitic bedrock falls above Keshena Falls Dam within the Menominee Indian Reservation, Wisconsin. As air temperatures plummeted in the days following heavy rains and break up of winter ice, the cascading waters were super-cooled, turning the river into a nearly 300-foot-wide frazil ice machine. The flowing ice particles, fragments of the region’s glaciated past, buckled the 13-foot-high timber-crib Keshena Falls Dam, itself a remnant of log drives on the Wolf River dating to the 19th Century. The breach released frigid water and ice towards the town of Keshena, WI located less than one mile downstream. The falls of the Wolf River were once the “drum” which drew the sturgeon, a traditional source of sustenance for the Tribe, home to spawn within the Tribe’s lands. Since the dam failure, the falls have instead become a damaging source of flooding as a large portion of the ice flows generated by the upper falls are no longer obstructed by the dam enroute to town. Furthermore, a hydroelectric plant which once operated at the dam providing electricity to tribal members has also been abandoned. This presentation will examine the cause and impacts of this little-known dam failure based on research of historical documentation available from the Wisconsin Department of Natural Resources Dam Safety Program and interviews with tribal officials. The results of this research highlight a dam failure case history which continues to impact the downstream community over 50 years after the event. The results also highlight ice loading, an often-overlooked potential dam failure mechanism, and this presentation will provide a discussion of the primary engineering considerations associated with ice loading on dams.