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Mancos Project Colorado: Montezuma County Upper Colorado Region Bureau of Reclamation The Mancos Project in the southwest corner of Colorado consists of the Jackson Gulch Dam and Reservoir, the Inlet Canal, and the Outlet Canal. Project lands extend downstream about 10 miles. The project can furnish a supplemental water supply to 13,746 acres. PLAN The offstream reservoir is fed by the 2.6-mile-long Inlet Canal from the West Mancos River. Water from the reservoir is returned to the original streambed at a point higher than the project lands through the 2.2-mile-long Outlet Canal. The greater part of the distribution system was constructed by local interests prior to 1900. Facilities constructed by the Bureau of Reclamation furnish supplemental water to an established agricultural area and provide a domestic water supply for Mesa Verde National Park, Mancos Rural Water Co., and the town of Mancos. Jackson Gulch Dam and Inlet Canal Jackson Gulch Dam is a rock-faced earthfill structure 180 feet high with a concrete cutoff wall. The reservoir is Jackson Gulch Darn Region Revision 9/82 (From Project Data Book) offstream on Jackson Gulch, 5 miles north of Mancos, and has a total capacity of almost 10,000 acre-feet. The dam does not have a spillway. The 280-cubic-foot-per- second-capacity outlet works is a concrete pressure con- duit from trashrack to gate chamber, and a steel pipe from gate chamber to two hollow jet valves. The Inlet Canal extends from the West Mancos River to the reser- voir. DEVELOPMENT Early History Settlement and irrigation of the Mancos Valley began about 1876. The natural flow of the Mancos River dur- ing the months of July, August, and September is very low, and the irrigation water supply for these months was inadequate. By 1893, when a State adjudication of water was made, late summer demands for irrigation water far exceeded the supply. To alleviate the shortage, three small reservoirs storing approximately 1,500 acre-feet of water were built by local irrigation organizations. Investigations In 1937, Bureau of Reclamation investigations led to the conclusion that the Jackson Gulch Reservoir site, an off- stream storage basin, was the only site of sufficient size to furnish an adequate project water supply. At that time, the project did not appear economically feasible but it received further consideration under the Water Conser- vation and Utilization Act of August II, 1939. Detailed project investigations, initiated in November 1940, followed approval of the project. Authorization The project was approved by the President on October 21, 1940, under the Water Conservation and Utilization Program Act of August II, 1939 (53 Stat. 1418), as amended October 14, 1940 (54 Stat. lII9).