WSPC05202

• File Number: 7630.625
• Description: Wild and Scenic - Wild and Scenic Rivers Act
• State: CO
• Basin: Statewide
• Date: 8/13/1981
• Author: Various
• Title: Comments - RE-South Platte River Basin Interim Report
• Water Supply Pro - Doc Type: Report/Study

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DEPARTMENTF THE ARMY

OMAHA. DISTRICT CC '~PS OF ENGINEf.RS
6014 U.S. POST OFFIC: AND COURTHOUSE
()MA~;A NEBr; .\5KA 68102

REPLY TO
ATTENTION OF"

MROPD-P

10 September 1981

Mr. Dan Merr:iman
Colorado Water Conservation Board
823 State Centennial Building
1313 Sherman Street
Denver, CO 80203

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Dear Mr. Merriman:

This responds to the Colorado Water Conserva~ion Board's request for our
comments on the Interim Report - South Platte River E3.s~n Assessment. B3.sed
on a cursory review of the alternatives and their potential impacts, we have
the following comments.

The use of the mean undeveloped streamflow values frc.ll table 13 appears to
be questionable for evaluating the potential of some of the alternatives.
For example, under alternative 1, the flood control storage of Chatfield
Reservoir would be reallocated to allow 45,000 acre-feet of the flood con-
trol pool each year for municipal water supply storage. However, review
of the Waterton undeveloped streamflow data indicates that 45,000 acre-feet
were available in only 5 of the 26 years presented in table 13. Inflows
from Plum Creek would most likely not be enough to make 45,000 acre-feet
avai.lable many more than those 5 years. The same logic applies to al ter-
native 2 "mere 30,800 acre-feet were available in only 5 of the 26 years.
In the case of Two ForI,s Reservoir, flows from these 5 years could be stored
to average: 30,800 acre-feet peel. ,'{ear; hcwever, .Ulis "<cems mllikely. All of
the alternatives should be reevaluated to deterrrune if the proposed water
diversions are available every or most of the years.

1he monetary impacts do not seem to be presented properly, For example, the
75,000 acre-feet used for alternative 1 would not be available every year;
therefore, the estimated annual value of the water supply would be somewhat
less than $7,5 million. Also, it was asswned that the water would be used
only once, as a municipal water supply. The 50,000 acre-feet of alternative
1 would have a value as do~~stream irrigation water after it has been used
as a municipal or industrial water supply; therefore, the monetary balefits
should be adjusted to reflect multiple use of the water that is not consump-
tively used,