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

'-'io
",,)
:';:0
-" (-,
", en

i
.:~

_ ~ 'i

:.',':
:';J';~~

,",)

- ;'!

(;}

';','';l

z-,,?
:J
'.' ~
!,_.'..

,..-J,;
~- :~
c',_ -~

~, .1

J
",:0)

In the upper reaches of the study area, the Blue River and Muddy Creek flow into the

Colorado River near Kremmling. Four dam sites are located in this vicinity, Alternative Wolford

Mountain Sites A' and C are located to the north of Kremmling on Muddy Creek. The Red Mountain

Site is 1 mile east of Kremmling on the Colorado River, and the Azure Site is 10 miles downstream to

the southwest of Kremmling on the Colorado River in lower Gore Canyon.

To the south of Kremmling, the existing Green Mountain Reservoir regulates the Blue River

to allow for out-of-priority diversions by the Colorado-Big Thompson Project and to provide water for

Western Colorado needs. Further up the Blue River, Dillon Reservoir stores flows which can be

diverted through the Roberts Tunnel. West of this area, closer to the confluence of the Eagle and

Colorado Rivers Is the Wolcott Site. It is located on a minor tributary to the Eagle River just north of

the town of Wolcott. It is an off-stream storage site that would be filled with water pumped from the

Eagle River, and, alternatively could also receive flows pumped from ttle Colorado River by a longer

route with a tunnel.

Hydrologic conditions prevailing in the Upper Colorado River Basin were evaluated to

estimate the yield from each reservoir site and to assess the ability of the proposed reservoirs to

meet the objectives of a Joint-Use Reservoir or to function as a Replacement Reservoir for the

Green Mountain Exchange Project. These hydrologic analyses included estimation of historic and

natural streamflows in conjunction with evaluating historic water use, Water rights and other legal

and institutional arrangements were examined that could affect river administration in the basin. In

addition, various levels of water development in the basin were examined to estimate potential

future water utilization. To effectively perform such hydrologic analyses, a review was made of

several existing hydrologic simulation models for their potential applications. The Boyle

Engineering Stream Simulation Model (BESTSM) was selected because of its unique capabilities for

handling the various hydrologic conditions encountered in the study area. BESTSM accounts for

monthly water volumes of inflows, diversions, return flows, river gains and losses, and outflows for

each segment of the stream system and allocates water based on the Colorado water rights priority

system and other legal and institutional arrangements.

5