WSP04772

• File Number: 8281.300
• Description: Colorado River Studies and Investigations - Colorado River Consumptive Uses and Losses Report
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/4/1991
• Title: Upper Colorado River Commission Staff Report
• Water Supply Pro - Doc Type: Report/Study

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In the UB series,
38) to sununarize
and type of use.

pie charts
Upper Basin

have been included
consump~ive uses

(UB-36 through
and losses, by

UB-
year

In the L.S series, the years 1971 through 1975 are often empty;
however, for those years, it cannot be assumed that the actual
consumptive use for the identified type of use is zero. The first
uses and Losses Report did not incorporate as much summary data 1n
the Lower Basin as did the later two reports. Similarly, the first
five years in this series may not be comparable because not all
consumpti ve use categories were included.

Coo:ments

The overall data
are substantial.
in agricul tural
Colorado, the
are decreased
been made' in
Colorado.

differences in the draft Uses and Losses Reports
In the Upper Basin, much of differences occurred
uses, mainly in Colorado, New Mexico and Utah. In
differences are mainly in agricul tUl"al uses, which
up to 150,000 acre-feet per year. These changes have
conjunction wi th data provided by the State of

The most striking differences are evident in New Mexico.
Irrigation uses have been decreased 1n the San Juan Basin in excess
of 60,000 acre-feet per year. Other changes, such as municipal and
industrial uses 1n New ~1exi co, were increased.

The changes in the Lower Basin are minimal, except for changes
New Mexico, which are significant. In my August 25, 1989, memo,
pointed out that the main stem channel losses were not reported
1981 through 1985. Fortunately, this has been included in
latest draft. However, I take strong exception to the data
years 1982 and 1984. As seen on
the chart to the right, the data
in these years are ,negative.
This is because the channel
losses are computed rather than
measured. All known - diversions
and evaporations are backed out
of the water balance in the
lower basin. Any water that is
unaccounted for is deemed to be
channel loss. While I do not
argue with this accounting
methodology, the logical lower
limit to this procedure should
be zero, rather than a negative
number. A naga ti ve number
suggests that there 1S water
added to the system in the lower
basin channel. In the context of
only happen when water is imported

RESERVOIR EVAPORATION
CHANNEL LOSSES

400

200

o

-200

-"""

-....

11 72 73 74- 715 71S n 76 n 60 111 82 83 54 56
Water Year

this
over

report,
the basin

such an even t can
boundary, such as

2

in
I
for
the
in