Hold Back the Dam, Boys! The Story of the Minnedosa Spillway Failure - May 1948

The Minnedosa Dam was constructed in 1912 by the newly formed Minnedosa Power Company. The lake impounded by the dam soon became the centerpiece of this burgeoning town in southwest Manitoba, Canada, supplying a source of electrical power, recreation, and pride to the community. Like many dams even today, the dam owners and the surrounding community reaped the benefits provided by the dam, but did not understand nor care to understand its behavior and performance. Years of warning signs of potential problems with the dam were swept under the proverbial rug; nothing could sway the growing prosperity of the town.
The spring of 1948 began like many others before. Heavy snow melt occurred during the spring thaw but little attention was paid to high lake levels or increased spillway discharges. That all changed on the morning of Saturday, May 1, 1948, when a local fisherman noticed large cracks in the spillway and soil and gravel being steadily washed downstream. Alarms were quickly raised throughout the town and surrounding region. However, valiant attempts by the community were not enough to save the spillway, and three days later, on the evening of Tuesday, May 4, 1948, the Minnedosa spillway failed catastrophically by overturning into the large scour hole that had formed at its toe.
While the mechanics of this failure are fascinating and there are many technical lessons to be learned, this is a story of the human factor. It is a story of greed by big business; failures in the transfer of knowledge; willful, yet blissful ignorance of the forces at hand; and a community who came together and risked everything to save their lake and their town.