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Mancos Project
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Mancos Project History (58 KB) (pdf)
General Description| Plan| Development| Benefits


General Description

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.

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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.

Facility Descriptions
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 off-stream 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 conduit 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 reservoir.

Operating Agencies

Operation and maintenance of the project was transferred to the Mancos Water Conservancy District on January 1, 1963.

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Settlement and irrigation of the Mancos Valley began about 1876. The natural flow of the Mancos River during the months of July, August, and September was very low, and the irrigation water supply for those 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.


In 1937, Bureau of Reclamation investigations led to the conclusion that the Jackson Gulch Reservoir site, an offstream 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 Conservation and Utilization Act of August 11, 1939. Detailed project investigations, initiated in November 1940, followed approval of the project.


The project was approved by the President on October 21, 1940, under the Water Conservation and Utilization Program Act of August 11, 1939 (53 Stat. 1418), as amended October 14, 1940 (54 stat. 1119).


Construction began on July 24, 1941, and completed on May 18, 1950. The first water from Jackson Gulch Reservoir was delivered to the water users in 1949. Construction for this project was delayed by World War II. The Civilian Conservation Corps (CCC) started to build the dam under Bureau of Reclamation supervision. In March 1942, the CCC organization was disbanded and a group of Civilian Public Service assignees resumed the construction work by contract after the war ended. The major project works were completed between May 1947 and December 1948.

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A dependable supplemental water supply for project lands adds to the economy of the area. Principal crops are alfalfa, grass hay, irrigated pasture, wheat, oats, barley, and corn silage.

Domestic, Municipal and Industrial

The community of Mancos, to ensure a permanent source of domestic water for the future growth of Mancos Valley, has subscribed for reservoir storage. The reservoir also provides water for Mesa Verde National Park and the Mancos Rural Water Company.

Recreation, Fish & Wildlife

Jackson Gulch Reservoir has a surface area of about 220 acres at total capacity. The reservoir is stocked with trout by the Colorado Department of Natural Resources, Division of Wildlife. There are many good camping and picnicking sites, and hunting for the plentiful deer and elk in the area is permitted in season. Recreation facilities at the reservoir were developed and are managed by the Bureau of Reclamation.


The Mancos Water Conservancy District privately constructed and operates a 25-kv powerplant on this project.

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Last updated: May 11, 2011