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 7 of 12

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Alternative Id: Modify CBT West Slope Facilities Operations
Alternative Ie: Denver Water system modified operations
Alternative If: Bypass diversions to storage

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. Alternative Ig: Reduce constraints on CROP'S

The StateMod model calculated that the effects of supplying the 20,000 acre-feet on reservoir storage,
reservoir yield, reservoir operations, hydropower generation, ffiBfleI water deliveries, channel constraints, and
the Check Case Settlement willwould vary among these alternatives. These effects are briefly summarized in
this report and presented in detail in the Technical Memoranda. The results discussed below and in the
Technical Memoranda assume that the StateMod model accurately simulated reservoir operations in this
study. That asslImption has been questioned Some study participants have questioned that assumntion,lH'lll,ffi
some oases, diSjlroyed BY study partisipaflls. However, the study participants res agreed the studies were
sufficient and to document the results of the study and move on to discussing what can realistically be
accomplished to meet the 20,000 acre-foot goal.

The study showed that the above alternatives were generally able to replace the 20,000 acre-feet
releaselbypass by diverting to storage under the reservoirs' refill rights. This replacement was generally done
within a period of several months, In some cases (e.g. Granby Reservoir) the replacement was not completed
for several years. In the case of Granby Reservoir, replacement of the 20,000 acre-feet releaselbypass to the
IS-Mile Reach was probably delayed because Granby Reservoir does not have a decreed refill priority._ In
general, however, replacement of the 20,000 acre-feet by diverting to storage under the reservoirs' refill rights
proved to be more efficient, effective, and less costly, than some of the measures incorporated into the above
alternatives for providing sources of replacement water for the 20,000 acre-feet releaselbypass.

Because of this, replacement of the 20,000 acre-feet should be done by diverting to storage under the
reservoirs' refill rights rather than utilizing some of the specific strategies included in the above alternatives
for replacement One issue that will have to be addressed is that most existing refill rights are not decreed for
this new use. Therefore, most of the reservoirs would require new junior refill rights for this new use.

The only Expanded CROP alternative that the study showed was not feasible in its proposed form was
Alternative Ib, Ruedi Reservoir Operations, which was not able to make the full 20,000 acre-feet
releaselbypass because of: (I) downstream channel constraints and (2) limited physical water availability ef
flew which prevented the replacement of the 20,000 acre-feet in Ruedi Reservoir under the Reservoir's refill
right For these reasons, the consultant team recommends that Ruedi Reservoir's contribution to the
20,000 acre-feet releaselbypass be limited to 7,000 acre-feet or less,

The ~Coordinated Reservoir Augmentation Project::- consists of Alternatives If and Ig. The "Coordinated
Reservoir Augmentation Project:: attempts to minimize the risk to individual facilities by placing
responsibility on as many facilities as possible for supplying some portion ofthe 20,000 acre-feet to the 15-
Mile Reach. Analysis of this alternative indicates that the 20,000 acre-feet can generally be replaced in the
various facilities by diverting to storage under the reservoirs' refill rights or a new refill right The
~Coordinated Reservoir Augmentation Project:: may also be necessary because of the limited release capacity
at some of the reservoirs, For example, Green Mountain Reservoir was restricted from making both the
estimated CROP bypasses and the 20,000 acre-feet release in one of the eight years of the study period in
which the 20,000 acre-feet release would be required.

Technical Memorandum No.7 (Appendix H) utilized both a proportionate release among nine reservoirs, and
an equal release among three reservoirs to model the -~Coordinated Reservoir Augmentation Project: A
Modified -~Coordinated Reservoir Augmentation Project:: was developed in which responsibility for

Flood Protection. Water Project Plarming and Finance. Stream and Lake Protection
Water Supply Protection. Conservation Planning