WSP07709

• File Number: 8281.300
• Description: Colorado River Studies and Investigations -- Colorado River Consumptive Uses and Losses Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1977
• Title: Colorado River System Consumptive Uses and Losses Report -- 1971-1975
• Water Supply Pro - Doc Type: Report/Study

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the Colorado River Basin is defined as ". . .all
of the dJainage area of the Colorado River
system ~nd all other territory within the
United states of America to which waters of
the Coldrado River system shall be benefI-
cially applied." The compact divided the Colo-
rado Riv~r Basin into two sub-basins-the
"Upper ~asin" and the "lower Basin," with
Lee Ferr~ as the division point on the river.
Lee Ferrx. located in Arizona. is a point in
the main~tream 1 mile below the mouth of
the paria\ River. For the purpose of thisre-
port. the !Great Divide Basin. a closed basin in
Wyoming, and the White River in Nevada have
not been ~onsidered as part of the Colorado
River sys~'em. Diversions from the system to
areas out~ide its drainage area are consid-
ered herein as exports and have not been
classifiedias to types of use.
Beneficial consumptive use is normally con-
strued to mean the consumption of water
brought a~out by human endeavors and in this
report incl:Udes use of water for municipal,
industrial.lagricultural, power generation,
export. recreation, fish and wildlife, and
other purp~ses. along with the associated
losses inci~ental to these uses.
The stor~ge of water and water in transit
may also act as losses on the system although
normally s~ch water is recoverable in time.
Qualitatively, what constitutes beneficial
consumptive use is fairly well understood;
however, a~ inability to exactly quantify these
uses has le~ to various differences of opinion.
The practical necessity of administering the
. various wat~r rights, apportionments, etc., of
the Colorad~ River has led to definitions of
consumptiv~ use or depletions generally in
terms of "h~w it shall be measured." The
Upper COlor$do River Compact provides that
the Upper C9'orado River Commission is to de-
termine the ~pportionment made to each
State by ". .1. the inflow-outflow method in
terms of manmade depletions of the virgin
flow at Lee ~erry. . . ." There is further pro-
vision that th:e measurement method can be
changed by t.(nanimous action of the Com-
mission. In cbntrast, article HAl of the decree
of the Supre,*e Court of the United States in

Arizona v. California defines, for the purpose of
the decree, "Consumptive use means diver-
sions from the stream less such return flows
thereto as are available for consumptive use
In the United States or in satisfaction of the
Mexican Treaty obligation." Nearly all the water
exported from the Upper Colorado River sys-
tem is measured; however, the remaining bene-
ficial consumptive use. for the most part.
must be estimated using theoretical methods
and techniques. In the Lower Colorado River
system tributaries to the mainstream, similar
methods must be employed to determine the
amount of water consumptively used.
Reservoir evaporation loss is a consumptive
use associated with the beneficial use of
water for other purposes. For the purpose of
this report, main stem reservoir evaporation is
,carried as a separate item for the Upper and
Lower Basins.
Channel losses within the system are nor-
mally construed to be the consumptive use by
riparian vegetation along the stream channel
(or conveyance route) and the evaporation
from the stream's water surface and wetted
materials. Seepage from the stream normally
appears again downstream or reaches a ground
water aquifer where it may be usable again. A
decided lack of data and acceptable methodol-
ogy along with the intermittent flow charac-
teristics of many Southwest streams com-
bine to make a reasonable determination of
channel loss difficult. Channel losses have
not been estimated for this report within the
Upper Basin nor on the tributaries of the
Lower Colorado River mainstream. Channel
losses on the mainstream below lee Ferry
have been estimated primarily by the
inflow-outflow method.

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Methodology and Data Collection

This initial report is based almost entirely on
data obtained from ongoing programs and cur-
rent reports. No new land use surveys were ini-
tiated.Available quantitative measurements
of water were used wherever their use aided
or complemented the determination of con-
sumptive use.

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