1952 Failure of Frenchman Creek Dam

The Frenchman Creek Dam was constructed in 1951 and was tested early in its life…it failed the test. A long winter that included record snowfalls ended in April 1952 with warming temperatures, filling many rivers in the Missouri Basin, including Frenchman Creek. The first flows over the spillway were on April 6, and the reservoir continued to rise over the next week. On April 15, the reservoir was spilling over the west dike, which was considered an emergency spillway. Later that day, with nearly 10-feet of flow over the spillway, the embankment breached. Photo documentation and reports demonstrate that the embankment did not overtop. Based on a review and evaluation of various documentation of the failure, including photographic documentation of the failure progression, experts concluded that an internal erosion initiated along the left spillway wall, progressing to a full embankment breach.
This paper explores the previous investigations and documentation including review and presentation of photos taken during and after the failure, along with opinions on cause from early reports from the failure.