WSP09055

• File Number: 8281.100
• Description: Colorado River Studies and Investigations -- Availability of Water-Hydrologic Determination
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1988
• Title: Hydrologic Determination - 1988 - Water Availability from Navajo Reservoir and the Upper Colorado River Basin for Use in New Mexico
• Water Supply Pro - Doc Type: Report/Study

,
"

, ,
....'

, ,
, "
: ,Basin, consensus on the appropriate procedure for employing
limited further investigation into this possibility at that

the CRSS model
time.

Co")
(:)
N
-J
C.'"
00

On July 10, 1985, the Secretary of the New Mexico Interstate Stream Commis-
sion formally requested that Reclamation continue to pursue a review based
on the CRSS of water availability in the Upper Colorado River Basin with
the focus toward a re-determination of the water supply available for use
in New Mexico. This investigation is a result of that request and will'
further examine the use of the CRSS data base for Upper Basin yield
estimations.

. ,-,,-'

III. Hydrologic Investigation

The Oepart*ent of Interior's,past position on water availability in the
upper Basin assumed that up to 5.8 MAF of water could be safely depleted
annually in the Upper Basin. This number was derived from an annual
virgin flow data base and developed with three assumptions: (1) the lowest
34-year period of natural runoff; (2) assigned tolerable shortages to
irrigated agriculture; and (3) delivery of half the Mexican Treaty
commitment from the Upper Basin.

Throughout the hydrologic investigation, and as demonstrated in the at-
tached tables, present Colorado River Storage project (CRSP) operating,
policy, along with required Upper Basin water deliveries, combine to form
the underlying assumptions that are integral to a hydrologic determination
of water availability from Navajo Reservoir and the upper Colorado River
Basin for use in New Mexico. To determine required water deliveries for
the Upper Basin, the then current depletion projections were employed by
the Bureau in,a "demand data base" for the 1984 hydrologic investigation.
This depletion schedule for the Colorado River System is periodically
updated and the current version can be found in the Bureau publication,
Quality of Water - Colorado River Basin Progress Report No.13 ~ January
1987. The report updates depletion projections for the river system
through year 2010. These projections were then extended through year 2040
to serve in the demand data base for this 1988 investigation and can be
found in Appendix I of the report.

The extended depletion schedule is based on the
Basin level of depletions will reach 5.8 MAF in

hypothesis that
the year 2040.

the Upper
The examin-

3