Blue Mesa Dam
Blue Mesa Dam, is located on the Gunnison River about 30 miles below Gunnison, and 1.5 miles below Sapinero, Colorado. Completed in 1966, the 390-foot tall (119 meters) [342 feet above streambed] zoned earth and rock-filled embankment is the uppermost dam on the Gunnison River. It contains three zones of selected rock, cobbles, sand, and clay totaling 3,093,000 cubic yards of materials (2,364,768 cubic meters) and has a crest length of 785 feet (239 meters). Blue Mesa Dam was the first to be built and is the largest of the three Aspinall Unit dams intended to store and control spring flows on the Gunnison River. Blue Mesa Reservoir is the largest body of water in Colorado stretching a distance of 20 miles (32 meters) with 96 miles (154 meters) of shoreline. When the reservoir is full at elevation 7,519 feet above sea level (2,293 meters) it has a total capacity of 940,800 acre-feet (1,160 million cubic meters) and a surface area of 9,180 acres (3,715 hectares).
Water is released from Blue Mesa Reservoir through large pipes called penstocks that extend through the dam and into the powerplant where the water turns turbines that generate electricity. Blue Mesa Powerplant contains two generating units with a total capacity of 86 megawatts. Additional water can be released through the outlet works and the spillway.
When potential dam sites were being investigated, cost studies indicated that it would be more economical to construct Blue Mesa Dam as an earthfill dam rather than a concrete dam. This resulted in a slight modification to the location the dam would be built which also had several additional benefits including reduced distance for hauling earthfill material, easier access to the powerplant, reduced embankment volumes, and better spillway alignment.