BOARD01355

• Board Meeting Date: 5/19/2003
• Description: WSP Section - Colorado River Basin Issues - Coordinated Facilities Operations Study
• Board Meetings - Doc Type: Memo

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Agenda Item 27 - Coordinated Facilities
May 19-20, 2003 Board Meeting
Page 9 of 12

years when this release would not be required, Therefore, the Webster Hill Reservoir alternative would
produce yield with a greater reliability than is required. It makes sense as a next step to analyze the economy
of scale of building Webster Hill Reservoir to provide both the 10,825 acre-feet committed by the water users
and the 20,000 acre-feet that is the subject ofthis study.

Feasibility of Power Plant Operations and Scheduling Alternatives

Alternative Sa, East Slope Power Operations and Scheduling, was investigated as one component of Alternative
I d, CBT West Slope Facilities Operations. This alternative primarily consisted of: (1) delaying winter deliveries
through the Adams Tunnel, (2) using these delayed winter deliveries to replace the releaselbypass of the 20,000
acre-feet from Granby Reservoir to the IS-Mile Reach and (3) replacing the delayed deliveries to east slope
reservoirs by diversions to storage in these reservoirs under the east slope priorities,

Alternative Sa was not modeled because:

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This alternative cannot be fully investigated using StateMod and the Cl data set. StateMod and
the CI data set only cover the Colorado River basin in Colorado and do not presentlv extend to
east slope facilities and systems, Specifically, StateMod and the Cl data set cannot be used to
detennine the quantity of deliveries through the Adams Tunnel that could be replaced through
use ofNCWCD's east slope water rights,

The Bureau of Reclamation in its October 12, 2001 letter to the Colorado River Water
Conservation District concludes that it is not feasible for a number of reasons to delay winter
and early spring deliveries of west slope water to the east slope via the Adams Tunnel in order
to keep east slope reservoir storage relatively low.

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Alternative I d was found to be an apparently feasible alternative for supplying the 20,000 acre-feet from
Granby Reservoir without the possible source of replacement water resulting from Alternative Sa.

Alternative Sb, Shoshone Power Plant, focused on general, not selective, removal of the Shoshone Power
Plant priority call. Analysis of this alternative indicated that general removal of this priority call would result
in an increase in stored water in those reservoirs, which could supply the 20,000 acre-feet to the IS-Mile
Reaeh,Reach: thereby reducing the risk of lower storage and/or lower reservoir yields accruing to those
reservoirs. Elimination of the Shoshone priority call decreased the value of Shoshone power production by an
average of approximately $116,000 per year. Therefore, it appears that Alternative Sb could be an efficient
and effective component of Alternative 6a, Insurance Pool, discussed below, Further sensitivity analysis of
this alternative was completed to determine the effects of removing the Shoshone priority call on November
through April Colorado River flows at the head of the IS-Mile Reach. Results of this analysis indicate that
the average monthly reduction in flows at the head of the IS-Mile Reach was approximately 6 cfs.

Feasibility of Other Alternatives

Alternative 6a, Insurance Pool, would establish an insurance pool to reduce the risk oflower storage and yields
to individual facilities providing all or a portion of the 20,000 acre-feet to the IS-Mile Reach. Two possibilities
for establishing an insurance pool were considered and investigated:

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Increasing the number of facilities providing a portion of the 20,000 acre-feet to the IS-Mile
reach, thereby spreading the risk among a larger number of facilities. Allocating responsibility
for the 20,000 acre-feet release among several reservoirs is necessary because oflimited release
capacity in Green Mountain Reservoir, which prohibits Green Mountain Reservoir from

Flood Protection. Water Project Planning and Finance. Stream and Lake Protection
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