PUB00027

• Year: 1990
• Title: Final Report Rio Grande Water Supply Study, Phase 1
• CWCB Section: Interstate & Federal
• Author: San Luis Valley Water Conservancy District
• Description: Reconnaissance level determination of the physically and legally available flow at 4 reservoir sites in the Rio Grande Basin upstream of Del Norte, Colorado
• Publications - Doc Type: Brochure

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compact commissioners were appointed and charged with preparing a compact which

equitably apportioned the waters of the Rio Grande.

In 1935, a Presidential mandate dictated that water development projects involving

the use of Rio Grande waters were not to be approved unless an opinion is obtained

from the National Resources Committee. The study of the National Resources

Committee, officially known as the Rio Grande Joint Investigation, was performed

during 1936 and 1937. At the time, the investigation (NRC, 1938) was believed to

have been the most comprehensive and detailed study ever made of water and land

resources of a river basin in the arid West.

The Rio Grande Joint Investigation was provided to the Rio Grande Compact

Commissioners in June, 1937 and provided factual data for further negotiations

between the three states. The Rio Grande Compact was signed by the Compact

Commissioners of Colorado, New Mexico and Texas on March 18, 1938. After

ratification by the state legislatures and consent of the U.S. Congress, it became

effective in 1940. A copy of the Compact is included as Appendix B.

The Rio Grande Joint Investigation also recommended a plan of development for the

San Luis Valley Project. As authorized by Congress in 1940 and described in House

Document 693, the San Luis Valley Project included a Rio Grande element (i.e. the

Wagon Wheel Gap dam), a Conejos River element (Platoro Reservoir), and a Closed

Basin element (i. e. Closed Basin Drain). The primary purposes of the San Luis

Valley Project were to assist Colorado in meeting its commitments to New Mexico and

Texas under the Rio Grande Compact and to assist the United States in meeting its

commitments to Mexico under the Treaty of 1906.

A 1947 "Supplemental Report, Conejos Division, San Luis Valley Project, Rio Grande

Basin, Colorado" prepared by the USBR recommended the construction of Platoro

Reservoir in the Conejos River Basin. Construction of Platoro Reservoir (67,800

af capacity) was initiated in 1949 and completed in 1951. Reservoirs constructed

after 1937 are subject to special restrictions of the Compact and therefore are

referred to as post-1937 or post-Compact reservoirs.

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