Overview
Blue Mesa Dam is on the Gunnison river about 30 miles below Gunnison, and 1.5 miles below Sapinero, Colorado. The zoned earthfill embankment has a structural height of 390 feet, a crest length of 785 feet, and a volume of 3,080,000 cubic yards of materials.
The spillway consists of a concrete intake structure with two 25- by 33.5-foot radial gates, concrete-lined tunnel, concrete flip bucket structure, and stilling basin. Maximum discharge of the spillway is 34,000 cubic feet per second.
The outlet works consists of an intake structure, tunnel, and manifold anchor block. The outlet works is controlled by one 16- by 18-foot fixed-wheel gate in the intake structure and by two 84-inch ring-follower gates and two 84-inch hollow-jet valves in a gate house at the terminus of the outlet conduits. Maximum discharge from the outlet works is 5,000 cubic feet per second at maximum water surface elevation, with two 84-inch hollow-jet valves 62 percent open.
Blue Mesa Reservoir has a total capacity of 940,700 acre-feet and an active capacity of 748,430 acre-feet. At maximum water surface elevation, the reservoir occupies 9,180 acres.
The Blue Mesa Powerplant consists of two 30,000-kilowatt generators, driven by two 41.55-horsepower turbines. Each Turbine is designed to operate at a maximum head of about 360 feet.
One 16-foot-diameter penstock conveys water to the two turbines and also carries water for the outlet works. After branching from the main penstock, each of the penstock laterals is controlled by 156-inch butterfly valves. The main penstock is reduced by a wye branch to the outlet works control valves.
Geology
The area has undergone a rather complex geologic development. The stmtigraphic column consists of basement, pre-Cambrian granite, gneiss, and schist, overlain uncomfortably by the Jurassic, Entrada sandstone, and shale, In turn progressively overlain by the Morrison Mancos clay shales. Structurally, the sedimentary strata, underlying the volcanics and overlaying the granites, dip to the north, with the horizontal overlaying volcanics covering their erosional truncated edges. The contact between the granite and sedimentary rocks becomes progressively lower in elevation to the north of the river. On the south side of the river, it rises to the ground surface. A large normal fault parallels the canyon on the southwest side, cutting close to the river at Cimarron, below Blue Mesa Dam.
