WSP11761

• 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 - Summary Report
• Water Supply Pro - Doc Type: Report/Study

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supplied by Green Mountain Reservoir. With the Replacement Reservoir(s) in operation, the water
that would have been released from Green Mountain Reservoir could instead be pumped to Dillon
Reservoir. This has been referred to as the "Green Mountain Pumpback" system.

PROJECT STUDY

Study of the Joint-Use Reservoir and Green Mountain Exchange Projects began in June

1985, when Boyle Engineering Corporation (Boyle) entered into contract with the Colorado Water

Resources and Power Development Authority. The Authority was created by the General Assembly

of the State of Colorado for the primary purpose of aiding in the planning, design, financing and

construction of water and hydroelectric power projects. There are nine members of the Authority,

eight of whom represen!.the major drainage basins in Colorado, and the ninth represents the City

and County of Denver. The Exchange Team, chaired by the Executive Director of the Authority, is a

subcommittee of the Metropolitan Water Roundtable and has served as an Advisory Committee

during the formulation and execution of the Study.

The purpose of this technical Study has been to estimate water yields for alternative Joint-
Use Reservoirs and alternative Green Mountain Exchange projects and to develop preliminary
designs and cost estimates based on an approximately uniform level of investigation. This
Inform!ltlon is required prior to any decision on the next level of development of these projects.

This Study has been conducted in three phases. In the first phase, existing data was

collected and evaluated for initial screening of nine reservoir sites identified by the Authority as

candidates for Joint-Use or Replacement Reservoirs. The candidate reservoir sites for this study

were selected based on the existence of a water right or claimed water right at the site and previous

studies conducted by the Colorado River Water Conservation District, the Denver Water Board, the

U.S. Bureau of Reclamation and others. The site selection was also based on geographic location

within the Colorado River drainage. The reservoir sites are displayed on Figure S.1.

An overview of previously published information about environmental concerns was

conducted for each reservoir site with the objective of eliminating sites with "fatal flaws". No

environmental issues were discovered which would eliminate any site from further consideration.

Three sites were eliminated through hydrological and geotechnical screening: Haypark, due to

insufficient water yield; Iron Mountain and Lower Piney because of geotechnical concerns.

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