WSP08519

• File Number: 8281.300
• Description: Colorado River Studies and Investigations - Colorado River Consumptive Uses and Losses Report
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 6/1/1991
• Title: Colorado River System Consumptive Uses and Losses Report 1981 - 1985
• Water Supply Pro - Doc Type: Report/Study

Consumpti"e Uses and Losses

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water surface and wetted materials.
Seepage fro/n the stream normally ,
appears agliin downstream or reaches a
ground-water aquifer where it may be
usable agaiil. A decided lack of data
and acceptable methodology along with
the intermittent flow characteristics of
many Sou~west streams combine to
make a reasonable determination of
channellos$ difficult. Channel losses
have not be~n estimated for this report
within the Vpper Basin nor on the
tributaries Of the Lower Colorado River
main stem. 'Channel losses on the main
stem below Lee Ferry and below Hoover
Dam were estimated.

METHODOLOGY AND DATA
ADEQUACY

This report is based almost entirely on
data obtained from ongoing programs
and currentireports. Quantitative
measurements of water use were used
wherever a"ailable, but the m~ority of
the basin water use was theoretically
calculated, The following sections
describe these calculations for both the
Lower Colorado River Main Stem and
the Upper ahd Lower Colorado River
Basin tributju'ies.

Colorado River
BasIn Trll)utarles

In the tributary areas of the basin,
records of diversions and return flows
are not complete enough to allow direct
calculation of consumptive water use.
Theoretical !ind indirect methods of
estimating cOnsumptive use must then
be relied upQn. In the New Mexico
portion of the Gila River Basin, the

annual consumptive use of water'iis
reported by the New Mexico Interstate
Stream Commission, pursuant to
article VII of the March 9, 1964, decree
of the United States Supreme Court in
Arizona va. California, et al.

Agriculture

The percentages of irrigation
consumptive use range between 64 and
69 percent for the Uppel' Basin tribu-
taries and between 73 and 81 percent
for the Lower Basin tributaries. Both
percent ranges exclude main stem
evaporation. The annual irrigated
acreage of most crops grown within each
reporting area was estimated from
information published in the yearly .
State Agriculture Statistics. Inifated
pasture and some minor crops not
reported by the State statistics were
estimated from information in the 1978
and 1983 National Census of Agriculture
with supporting information from the
comprehensive framework study and
various other local reports. The total
irrigated acreage values for the Upper
and Lower Basins are shown in
tables UC-7 and LC-9, respectively.

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Since most of these data were presented
on a county basis, it was necessary to
separate them into smaller reporting
areas for computational purposes. This
was accomplished using land inventory
maps and relationships developed for
the comprehensive framework study.

These subbasins generally follow
tributary stream basin and State
boundaries. A representative climatic
station was selected for each subbasin.
Using historical records of temperature,