Gold and silver mines were in abundance in the San Juan mountains of Colorado during the 1890’s. Fuel for powering the mines and mills extracting and refining these precious minerals was not. Telluride, Colorado entrepreneur Lucien L. Nunn set out to capitalize on his acquisition of regional water rights and his knowledge of waterpower as a solution for providing electricity to the mines. Nunn’s efforts culminated in the 1891 construction of the Ames Powerhouse and the first alternating current hydroelectric powerplant in the United States. Over the next several years, Nunn and the Telluride Power Company made improvements to the Ames plant, including the construction of three water storage reservoirs consisting of Lake Hope Reservoir dam, Middle Reservoir dam, and Trout Lake Reservoir dam to ensure reliable and sustainable hydroelectric power for the area.
Persistent and locally heavy rainfall occurred over southwestern Colorado and northwestern New Mexico from a general storm system passing through the region during the first six days of September 1909. Around noon on Sunday September 5, a localized storm produced heavy rainfall in the Middle Dam drainage basin. Two hours later, Middle Dam failed sending flood waters into Trout Lake reservoir and failing its dam. Downstream consequences from the dam failures were catastrophic including threat to life and the destruction of property, transportation rails and roads, and communication lines, followed by a lengthy delay of goods and services.
This paper uses historical reports and accounts of the 1909 failure of Middle Dam and presents the findings alongside modern dam safety engineering analyses of hydrology, failure mode(s), 2D dam breach modeling with terrain modification, downstream consequences, and risk. Results show how researching, evaluating, and modeling historic dam failures can strengthen our knowledge, regulation, and assessment of dam safety risks 115 years later
