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

~. Introduction' ,
". The Colorado River system is composed of
~".) portions of sevenIState~Arizona, California,
.,~ Colorado, Nevada" New Mexico, Utah, and
-, Wyoming. It has a drainage area of about
""'242,000 square Tiles and repres~nts about
one-fifteenth of toe area of the U ntted States.
This report incorporates annual estimates of
consumptive uses land losses of water from the
system from 197[ to 1975. Wherever
available, water Jse reports prepared in
accordance with Ihgal requirements concerning
the operation of t~e Colorado River were
utilized. Base dat~ needed to estimate onsite
consumptive useslwere taken largely from.
existing reports and studies and from ongoing
. programs. Where qurrent data were not
available. estimat~d values were developed by
various techniques ~nd reasoned judgment. No
new surveys or spedal studies were undertaken
for this initial report.. In general, methodology
followed the techni4ues normally used within
the system for estinjating water use.)'NOtI1~n~ in
this report is intendqd to interpret the provIsions
of the Colorado River Compact (45 Stat. 1057),
the Upper Colorado kiver Basin Compact (63
Stat. 31), the WaterjTreaty of 1944 with the
United Mexican Stat~s (Treaty Series 994; 59
Stat. 1219), the decree entered by the
Supreme Court of the; United States in Arizona v.
California, et al. (37E$ U.S. 340), the Boulder
Canyon Project Act (45 Stat. 1057), the Boulder
Canyon Project Adjus~ment Act (54 Stat. 774;
43 U.S.C. 618a), theiColorado River Storage
. ,
Project Act, (70 Stat. ;105; 43 U.S.C. 620), or
the Colorado River Ba$in Project Act (B2 Stat.
885; 43 V.S.C. 150!;).

Authority

The authority for thi$ report is contained in
Public Law 90-537, tHe Colorado River Basin
Project Act of 1968. Title VI, section 601(b)(l)
of the act reads as follqws:
(b) The Secretary is ~irected to-
(1) Make reports!as to the annual
consumptive uses and losses of water from
the Colorado River system after each
successive five-year, period, beginning with
the five-year periOd!starting on October 1,
1970. Such report~ shall include a

detailed breakdown of the beneficial
consumptive use of water on .
State-by-State basis. Specific figures on
quantities consumptively used from the
major tributary streams flOWing into the
Colorado River shall also be included on a
State-by-State basis. Such reports shall
be prepared in consultation with the
States of the lower basin individually and
with the Upper Colorado River
Commission, and shall be transmitted to the
President, the Congress, and to the
Governors of each State signatory to the
Colorado River Compact.

Plan of Study

After initial meetings with representatives of
the Lower Basin States and the Upper Colorado
River Commission, a proposed plan of study was
presented for comment. Comments received
largely concerned water accounting pro-
cedures, particularly the lack of uniformity
and consistency within the system. This issue
is longstanding and is related to the
interpretation and implementation of the legal
documentary controlling the operation of the
Colorado River. In November 1974, a pre.-
liminary report was prepared which
included estimates of beneficial consumptive
use. Comments received from the States were
essentially the same as for the plan of study. In
the Upper Basin, the principal comment
concerned the use of 1965 data bases
developed for the Upper Colorado Region
Comprehensive Framework Study,
particularly irrigated acreage. In the Lower
Basin, the main concerns were the lack of
credit for unmeasured return flows originating
from mainstream diversions and the failure to
quantitatively recognize that ground water
overdraft in the Gila River Basin satisfies a
major portion of the beneficial consumptive
use. To the degree possible, these concerns
are addressed within.this report.

UPPER COLORAOO RIVER

The major tributary streams selected as
reporting areas in the Upper Colorado River
Basin are: Green River (Wyoming, Utah,
Colorado); Upper Main Stem (Colorado,
Utah), and San Juan-Colorado (Colorado,
3