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. 001865 " '3 Bureau of Reclamation - Rehabili~ation Program Operating Irrigation Projects - Orchard Mesa Division Grand Valley Project - Colorado Preliminary Inventory General Dsecription The Orchard Mesa Division, Grand Valley Project, Colorado, located south of Colorado river, extends from the town of Palisade along a narrow mesa to a point south of Grand Junction. The gross project area, about 10,000 acres, includes 456 acres, originally the East Palisade Irrigation District, now included with and supplied by the Orchard Mesa Irrigation District, organized under Colorado law. Most of the former East Palisade lands are supplied by gravity from the main power canal of the Orchard fuesa District, although small pumping plants supply some tracts above that canal. Orchard Mesa proper is supplied by two canals, with the following acproximate specifications: No.1, Nominal capacity, 80 second-feet; Lift, 44 feet; Length, 14.9 miles; No.2, Nominal capacity, 60 second-feet; Lift, 130 feet; Length, 20.8 miles. These canals eever respecitvely, 6,300 and 3,200 acres. actual irrigated area at present about 8,500 acres. Irrigation water is pumped by four direct connected reaction turbine -- cen- trifugal pump units, two for each lift, operating under a gross power head of 78 feet. Each turbine and pump are fed from the same pensoock, so that the lifts as shown are only the pumpi~lift from the water level of the main canal to that of the distribution canals. The main power canal is supplied by the main canal of the Grand Valley Project, near the upper end of tunnel No.3, 4.60 miles below the Grand River Diversion dam of that project. Here the water of Orchard Mesa crosses under Colorado river in a 9 foot circular concrete siphon and is carried for 3.50 mimes, half in bench or box flwne and half in the old canal alignment to the pump- ing plant on the left bank 6jj Colorado river, one mile south of Palisade. Alongside the Orchard Mesa pumping plant, the power plant of the Grand Valley Project contains two 1,500 kilowatt generators driven by reaction turbines with individual pensollcks. The turbines discharge into a tailrace used by both plants, which in some 500 feet empties into Color2do river. The power plant has the use of 400 second-feet during the irrigation season and for the rest of the year the whole capacity of the power canal, nominally 800 second-feet. when flow of Colorado river falls below about 2,000 second-feet the combined demand of all Grand Valley irrigation systems exceeds available water. Under this condition tail aster from these plants is checked up where the tailrace falls into the river and diverted about one-fourth mile upstream and returned to the river where it can be rediverted by the Grand Valley Irrigation Company. The Company, owner of an original decree for 520.81 second-feet is the senior of all appropri- ators fram Colorado river in Colorado and must be supplied, but Oy-passing this water permits of a double use. The usual pvwer release being on the order of 725 second-feet, not only the original decree of the Grand Valley Company, ,but its junior supplemental decree lIhich brings its total to 640.49 second-feet are thus adequately supplied. Operation of this by-pass, which has become more frequent in recent years gas disclosed some of its shortcomings as treated later herein. ===-