WSPP282

• File Number: 8240.200.39.C
• Description: Colorado River Threatened-Endangered - RIPRAP - CFOPS - Water Availability
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/1/2003
• Author: Brown and Caldwell
• Title: Phase 2 Coordinated Facilities Water Availability Study for the Endangered Fishes of the Upper Colorado River - Tech Memo Number 12 - Comments-Responses to 01-01-03 - Draft - 03-01-03
• Water Supply Pro - Doc Type: Report/Study

000686

EXECUTIVE SUMMARY

The comments received are attached with specific responses in Track Changes format. Changes in
response to these comments will be included in the final report.

The reviewers in their comments noted many occurrences of "Why did this parameter go up when it
should have gone down?" There were also a number of comments questioning the
applicability/acceptability of the Ground Rules, Assumptions and Analysis Procedures agreed to at
the start of the investigation. These Ground Rules, Assumptions and Analysis Procedures are
repeated in Chapter 2 of the Draft Final Report and a copy of Chapter 2 is attached for your review.
In response to these and other comments Brown and Caldwell offers the following:

.

We have been working on this project since 1999.

.

We have revised the C1 Data Set five times to model reality better. These revisions
are detailed in the series of Technical Memoranda and the Phase 1 and Phase 2 Final
Reports.

.

StateMod was revised by CWCB and the State Engineer's Office to model reality
better. These changes are detailed in the Phase 2 Final Report.

.

We modeled 19 alternatives and did various modifications of these alternatives.

.

Sensitivity analysis was performed to determine the feasibility of making the 20,000
acre-feet release under future forecast depletion conditions.

Despite all these changes and modifications of StateMod and the C1 Data Set, the basic conclusions
have not changed:

\~

1.

Based on the 1975-91 hydrology study period and the assumptions and procedures
incorporated in the StateMod monthly time step modeling with the revised C1 Data
Set, there is adequate available storage and there are adequate available water rights
to fill the storage thereby facilitating the release/bypass of 20,000 acre-feet in those
years when the peak flow of the Colorado River at Palisade is between 12,900 and
26,600 cfs. Furthermore, based on the results of this investigation and the review of
these results by study participants, the required 20,000 acrecfoot release/bypass was
made in 8 years of ~he 17 year study period without reducing existing projects' yields.
This basic conclusion is true for a number of the alternatives, and combinations of
alternatives, investigated.

P,\Data \GEN\CWCB\19665\Repon Phase 2\ Technical Memorandum No. 12\ TechMemo12.2.28.03.doc

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