WSP00353

• File Number: 8240.200.43.H.2
• Description: Grand Valley/Orchard Mesa -
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/11/1993
• Title: Analysis of the Orchard Mesa Check Operation Under Current and Historic Stream Administration Practices
• Water Supply Pro - Doc Type: Publication

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The study indicates that the Check was operated in 35 of the 46 years within the period 1945
through 1990. During these years the Check was implemented when the Colorado River flow at
Cameo dropped below approximately 2,000 cfs and continued until flows increased or the irrigation
season ended. The amount of the Check varied from less than 10 cfs to as much as 582 cfs. In
the 11 years when the Check did not operate the flows measured at the Cameo gage did not fall
below 2,000 cfs during the irrigation season. A summary of the check operation is contained in
Attachment 1.

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WA TER RIGHT ADMINISTRA TlON - GREEN MOUNTAIN RESERVOIR

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The Cameo demand and Shoshone Power Plant located in Glenwood Canyon are considered the

controlling water rights on the mainstem of the Colorado River above the State line. As natural

streamflows drop below the respective water demands, these senior water rights place a call on

the river. The call sets in motion a series of steps taken by the Division Engineer to administer the

river within the prior appropriation system. Releases from Green Mountain Reservoir are an integral

part of the river administration.

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The operating policy for Green Mountain Reservoir was published in the Federal Register on

December 22, 1983. The policy establishes that the reservoir will be operated pursuant to Senate

Document 80, decrees and stipulations entered into in consolidated cases 2782, 5016 and 5017,

and applicable Reclamation laws. Under the operating policy, 66,000 AF have been set aside out

of the reservoir's 100,000 AF power pool to be utilized to meet the demands of historic agricultural

and municipal/domestic beneficiaries on the western slope. The 66,000 AF pool was estimated

by the Bureau to be the maximum amount of water necessary to meet the demands of west slope

beneficiaries in a critically dry year.

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When the Cameo or Shoshone call is placed the Division Engineer reQuests that the Bureau of

Reclamation release water from Green Mountain Reservoir to help supplement natural streamflows.

The releases are made first to offset the consumptive use of irrigation and domestic water users

who have perfected their rights on or before January 1, 1984. This release allows these junior

users to continue to divert water when they otherwise would be out-of-priority to either the

Shoshone or Cameo demand.

The 66,000 AF pool can also be used to directly satisfy the agricultural demand at Cameo. If
releases of water for the junior west slope beneficiaries are insufficient to meet the Cameo

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