WSP03373

• File Number: 8281.300
• Description: Colorado River Studies and Investigations - Colorado River Consumptive Uses and Losses Report
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/8/1991
• Title: Analysis of the draft Colorado River System Consumptive Uses and Losses report 1981-1985 -- Part 1 of 2
• Water Supply Pro - Doc Type: Report/Study

.

In the UB serles,
38) to summari ze
and type of use.

pie charts
Upper Basin

have been included
consumptive uses

year

(UB-36 through
and losses, by

UB-

~
,-;')
(:;,
~
-J
~

In the LS serIes, the years 1971 through 1975 are often empty;
~owever, for those years, it cannot be assumed that the actual
consumptive use for the identified type of use 1S zero. The first
uses and Losses Report did not incorporate as much surrunary 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
consumptive use categories were included.

Cooments

The overall data
are substantial.
in agricul tural
Colorado, the
are decreased
been made
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 agricultural uses, which
up to 150,000 acre-feet per year. These changes have
conjunction with data provided by the State of

in

The most striking differences are evident 1n New Mexico.
Irrigation uses have been decreased in the San Juan Basin 1n excess
. of 60,000 acre-feet per year. Other changes, such as municipal and
industrial uses 1n New ~1exico, 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 1S because the channel
losses are computed rather than
measured. All known' diversions
and evaporations are backed out
of the water balance 1n the
lower basin. Any water that 1S
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 negative number
suggests that there is water
added to the sys tem in the lower
basin channel. In the contex~ of this
only happen when water is imported

.

in
I
for
the
1n

RESERVOIR EVAPORATION
CHANNEL LOSSES

(...OOO~t)
000

...0

200

o

-2QO

-.000

-000

71 12 73 14 10 70 n 18 18 80 81 62 8S M ~
Water Year

over

report,
the basin

such an event
boundary, such

can
as

2