WSP12030

• File Number: 8441.400
• Description: Colorado Big Thompson Project - Reports
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 4/1/1987
• Title: Joint-Use Reservoir and Green Mountain Exchange Projects - Final Report
• Water Supply Pro - Doc Type: Report/Study

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3.2

ADMINISTRATION OF THE UPPER COLORADO RIVER

The administration ofthe Upper Colorado River is largely affected by two major water rights:

Cameo and Shoshone. The more senior of these and therefore higher priority, is the demand at

Cameo. It consists of a number of senior water rights for the Grand Valley Canal and the Grand

Valley Irrigation Project, some of which date to the late 1800's. The Grand Valley Irrigation Project

includes the Government Highline Canal and the Orchard Mesa Canal rights which are diverted from

the river at the Grand Valley Diversion Dam. ,he demand measured at the Cameo gage both for the

Grand Valley Canal and the Grand Valley Irrigation Project during the summer is normally In excess.

of 2000 cubic feet per second (cfs). However, if a check structure located at the atterbay of the

Orchard Mesa Power Plant is operated, whiCh allows the power plant tailwater to be used by the

Grand Valley Canal, the demand may be reduced to less than 2000 cfs.

The demand for water at Shoshone has a priority date of 1902 and a decreed diversion rate of

1250 cfs. It supplies the Public Service Company of Colorado's Shoshone hydroelectric plant in

Glenwood Canyon and is a year round non-consumptive use. The plant also has a junior water right

for 158 cfs with a priority date of 1929. In most years, when the 1902 right at Shoshone is satisfied,

there is sufficient water to meet the summer demand at Cameo. Downstream of the Shoshone Power

Plant, before reaching Cameo, the Colorado River flow is supplemented by tributary inflow largely

from the Roaring Fork River.

When flow is insufficient, a senior water right holder can place a call upon the river to which

junior rights must defer and reduce diversions. Many junior diversions in the Upper Colorado River

Basin have been protected from the Shoshone or Cameo calls by the replacementfunction of several

reservoirs. For example, the major function of the Williams Fork Reservoir is to allow for out-of-

priority diversions by the Denver systems, and one of the functions of Ruedi Reservoir isto protect

diversions by the Fryingpan-Arkansas Project. Green Mountain Reservoir also has a replacement

function which warrants the following detailed description because of its significance to this project.

Operation of Green Mountain Reservoir

Green Mountain Reservoir, located on the Blue River, is a feature of the CBT West Slope

Collection and Storage System constructed by the USBR. Construction of Green Mountain dam was

completed in 1943.

3.3