WSP02976

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1979
• Title: An Economic Evaluation of the Salinity Impacts From Energy Development - The Case of the Upper Colorado River Basin
• Water Supply Pro - Doc Type: Report/Study

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industrial water use are based on information
from the 1975 Water Assessment. Future
irrigation development is based on authorized
projects as reported by the U. S. Department
of the Interior and presented in Table 4. A
summary of the information used for 1985 and
2000 levels of water use is presented
in Table 5.

QQper Basin water supply -
Ehysical and le~al considerations

The amount of water available to the
Upper Basin states depends on both natural
and legal considerations. Consequently,
estimated amounts vary with the methods by
wh ich the stud ies were made and leg a 1 prov i-
s ions interpreted. In addition to state
laws which provide for intrastate control of
water, use of water in the Upper Colorado
River Basin is governed principally by three
documents: the Colorado River Compact of
1922, the Mexican Treaty of 1944, and the
Upper Colorado Basin Compact of 1948 (Hansen
1976). Among other provisions, the Colorado
River Compact of 1922 apportions to the Upper
and Lower Basins, each in perpetuity, exclu-
sive beneficial consumptive use of 7,500,000
acre-feet of water annually from the Colorado
River Basin. It further establishes the
obligation of the Upper Basin states not to
cause the flow of the Colorado River at Lee
Ferry to be depleted below 75 million acre-
feet for any period of 10 consecut ive years.
This provision is interpreted as requiring

delivery of 7.5 MAF annually to the Lower
Basin. The Mexican Treaty of 1944 ~uarantees
Mexico delivery of 1,500,000 acre-feet of
water annually from the Colorado River. The
Upper Colorado River Basin Compact of 1948
divides the water apportioned to the Upper
Basin among the Upper Basin states and
establishes principles to govern deliveries
of water to meet the Lee Ferry flow obliga-
t ion. By the compact, the Upper Basin
portion of Arizona is granted consumptive
use of 50,000 acre-feet annually and the
other states each receive percentages of the
remaining consumptive use as follows:
Colorado, 51.75 percent; New Mexico, l1.25
percent; Utah, 23.00 percent; and Wyoming
14.00 percent.

The two most familiar and widely accept-
ed figures for the annual Upper Colorado
River Basin water supply are the Department
of Interior's 5.8 MAF and the Upper Colorado
River Commission's 6.3 MAF (Hansen 1976).
The Department of the Interior figure is
based on delivery of 8.25 MAF to the Lower
Basin. Of this, 0.75 MAF is to satisfy the
Mexican Treaty and operate storage projects
to meet Upper Basin needs and downstream ob-
ligations through critical low-flow periods.
The 6.3 MAF suggested by the study for the
Upper Colorado River Commission is based on
delivery of 7.5 MAF per year to the Lower
Basin with no allowances made to satisfy
the Mexican Treaty and with no shortages
required of Upper Basin users. If these
differences in operating assumptions are

Table 4. Project of new irrigation lands (acres).

Subbasin and Count}

2000

1985

Subbasin 1
Subbasin 2
Savery - Pot Hook (Moffat)
Subbasin 3
Uintah Unit (Duchesne)
Deferred Indian lands
Central Utah Project - Jensen Unit
(Uintah)

Subbas in 4
Fruitland Mesa (Gunnison)
Subbasin 5
West-Divide (Garfield - C)
Sub bas i n 6
Monderu (Delores)
San Miguel (San Mi9uel)
Subbasin 7
Navajo Indian Irrigation
(San Juan - NM)
Animas - La Plata (La Plata)

()

o
o
o
4,300
D

14,400
7,800
17,000
~40

11 ,300

9,000

34,000
11 ,5DO

600
3,700

1,360
o

72,000
46,000

o
o

Total

9,960

223,440

Source: U.S. Department of the Interior, Quality of Water Colorado River
Basin, Progress Report No.8, January 1977, p. 63.

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