WSP04347

• File Number: 8282.600.10
• Description: Colorado River Operating Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/1977
• Author: USDOI/BOR
• Title: Operation of the Colorado River Basin 1977 Projected Operations 1978
• Water Supply Pro - Doc Type: Publication

Projected Plan of Operation
under Criteria for Current Year

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Looking upstream from east shore near Flaming Gorge
Dam.

Determination of "602(a) Storage"

Section 602(a)(3) of the Colorado River Basin Proj.
ect Act of September 30, 1968 (Public Law 90-
537), provides for the storage of Colorado River
water not required to be released under article
III(c) and Ill(d) of the Colorado River Compact in
Upper Basin reservoirs to the extent the Secretary
finds it to be reasonably necessary to assure Com-
pact deliveries without impairment of annual con.
sumptive uses in the Upper Basin, Article II of the
"Criteria for Coordinated Long.Range Operation of
Colorado River Reservoirs," pursuant to the act,
provides that the annual plan of operation shall
include a determination by the Secretary of the
quantity of water considered necessary as of Sep-
tember 30 of the current year to be in storage as
required by section 602(a) of Public Law 90-537
after consideration of all applicable laws and rele.
vant factors including, but not limited to: (a) his.
toric stream flows; (b) the most critical period of
record; (c) probabilities of water supply; (d) esti.
mated future depletions in the Upper Basin, includ.
ing the effects of recurrence of critical periods 01
water supply; (e) the "Report of the Committee on
Probabilities and Test Studies to the Task Force on
Operating Criteria for the Colorado River," dated
October 30, 1969, and such additional studies as
the Secretary deems necessary; (f) the necessity to
assure that Upper Basin consumptive uses are not
impaired because of fa'rlure to store sufficient wa.
ter to assure deliveries under section 602(a)(I)
and (2) of Public Law 90-537,

Taking into consideration these and other relevant
factors, the Secretary has determined that the ac.
tive storage in Upper Basin reservoirs forecast for
September 30, 1978, on the basis of average run.
off during the current year exceeds the "602(a)
Storage" requirement under any reasonable range
of assumptions which might be realistically applied
to those items which he is directed to consider in
establishing this storage requirement. Therefore,
the accumulation of "602(a) Storage" is not the
criterion governing the release of water during the
current year.

Storage in Lake Powell on September 30, 1977,
was 4.1 million acre.feet less than the storage in
Lake Mead on that date. Even with a minimal
scheduled release from Lake Powell of 8.23 mil.
lion acre.feet and assuming average runoff for wa-
ter year 1978, the Lake Powell active storage fore'
cast for September 30, 1978, is about 2.9 million
acre. feet less than the Lake Mead active storage
forecast for that date,

Therefore, the plan of operation during the current
year is based on a minimal release of 8,230,000
acre. feet of water from Lake Powell, in accordance
with section 602(a)(3) of Public Law 90-537.

Water skIIng on lake Powell, Utah-Arizona.