Generating capacity: 9 megawatts
950 Ennis Lake Road
Ennis, MT 59729
Madison Dam is a four-unit hydroelectric plant on the Madison River at the head of Bear Trap Canyon, about 10 miles north of Ennis, Mont. The units have a total generating capacity of 9 megawatts. (One megawatt can satisfy the average energy needs of 750 households.)
Madison Dam is 257 feet long and 35 feet high. An earlier dam and powerhouse originally went into operation in 1901; they were replaced in 1905-06. Its reservoir is 2.6 miles long and has a storage capacity of 27,200 acre-feet. The dam is classified as a “run-of-river” project because it can generate electricity using the water that flows down the river, without the need to store additional water supplies.
Madison Dam is one of eight hydroelectric plants and one reservoir along the Missouri and Madison Rivers covered under PPL Montana’s Project 2188 operating license. Through this license, PPL Montana works with state and federal agencies and private groups to implement a diverse array of environmental stewardship projects to protect habitats on or near the banks of the Missouri and Madison rivers.
Recreational floaters and kayakers are drawn to the white-water stretches of Bear Trap Canyon, which opens into a valley populated by a number of ranches and farms.
South of Madison Dam, just north of the Idaho border near Yellowstone Park, is PPL Montana’s Hebgen Lake.