Mio Hydroelectric Plant / Hydroelectric Power

The Mio Hydroelectric Plant was the fourth of six hydros built on the lower Au Sable River between 1909 and 1924 by Consumers Power Company, later Consumers Energy. Completed in 1916, it was the first hydro to pass excess river flow through concrete passageways or conduits built into the foundation of the powerhouse rather than over the dam through an above ground gated spillway, which was more costly. Known as a conduit spillway, it was invented and patented by William W. Tefft, a civil and hydraulic engineer for Consumers Power. (A gated spillway was also built.) In 1988 an aboveground concrete emergency spillway was built on the west side of the powerhouse to meet then current federal dam safety standards. Hydroelectric Power Flowing water has long provided power to mines and mills. With advances in electricity in the 1880s, waterpower was soon used to generate electricity. The first public demonstration of hydroelectric power in the country occurred on July 24, 1880, when sixteen carbon arc street lamps lit up Grand Rapids using a belt driven dynamo (generator) powered by a water turbine at the Wolverine Chair Factory. Michigan's extensive water resources were harnessed to power electric generating equipment, first at existing dams and mills and later at sites built expressly for hydroelectric generation. The electricity from these plants provided power for homes and businesses and helped fuel Michigan's growth as one of the nation's premier industrial states.