Glendo, Fremont Power Plant and Gray Reef
In the late 1950s, the Glendo unit, which included Glendo Reservoir, Gray Reef dam and the Fremont Power Plant, was constructed under federal legislation allowing for multi-purpose projects. These included for the first time flood control, hydropower, irrigation, municipal water, fish, wildlife habitat and recreation. Glendo, which is a multiple-use project, became the only Wyoming project of all the reservoirs to include flood control capacity.
A 17-foot-diameter underground tunnel, four miles through granite that Lawson said one could drive a bus through, was mined to deliver Pathfinder water to the Fremont Canyon Power Plant at the head of Fremont Canyon above Alcova Reservoir. This left that stretch of river, known as the Cardwell Access, nearly dry.
Up until this time, when the irrigation season was over Sept. 30, the river was basically shut off and wouldn’t flow until around May 1.
“Irrigation was done,” Lawson said. And there was no place to store the water without losing it.
But Gray Reef, a new, small dam below Alcova completed in 1961, was able to provide river flow equalization much like Kortes. Combined with excess capacity in Glendo, in which Pathfinder water could be restored if necessary, Gray Reef allowed the Bureau of Reclamation to smooth the river’s flow so they could generate electricity even in winter, where uneven flows caused dangerous problems with ice. The minimum flow avoided the icing problems and inadvertently created another stretch of valuable trout fishery.