BOARD00101

• Board Meeting Date: 7/26/1999
• Description: Colorado River Basin Issues - Grand Canyon Protection Act - Adaptive Management Program Status Report
• Board Meetings - Doc Type: Memo

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1340
STATE OF COLOMDO

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Colorado Water ConseNation Board
Department of Natural Resources
1313 Sherman Street
Denver, Colorado 80203
Phone, 13031866.3441
FAX, 13031 866-4474

MEMORANDUM

Bill Owens
Governor

CregE..Walcher
Executive Director, DNR
Peter H. Evans
Director, eWeB

TO:

Peter Evans, Director

FROM: Randy Seaholm #
Chief, Interstate Streams Investigations

DATE: July 23,1999

SUBJECT: Operations of Lake Powell inWater Year 1999

You requested that I explain the operations at Glen Canyon Dam during water year 1999.
Attached are the Lake Powell and Lake Mead pages from the July 9, 1999 24-month
study.

By way of background, each year the Annual Operating Plan (AOP) process provides
guidance regarding reservoir storage and release conditions for the upcoming year, based
upon Congressionally mandated storage, release, and delivery criteria and determinations.
After meeting these requirements, specific reservoir releases may be modified as forecast
inflows change in response to climatic variability and to provide additional benefits for
the multiple project purposes.

The Operating Criteria for the Upper Colorado River Basin reservoirs provide that the
annual plan of operation shall include a determination of the quantity of water considered
necessary to be in Upper Basin storage at the end of the water year. Historically, the
Secretary as found after taking into consideration all relevant factors required by the
Operating Criteria, that the active storage in Upper Basin reservoirs forecast for
September 30th exceeds the storage required under Section 602(a) of the Colorado River
Basin Project Act under any reasonable range of assumptions which might be applied.
Therefore, "602(a) Storage" has not been the criterion controlling the release of water
from Glen Canyon Dam during recent water years. Attached is a page that shows how
602(a) storage requirements have been determined in past modeling efforts.

Section 602(a)(3) of the Colorado River Basin Project Act further provides for the
storage of Colorado River water in Upper Basin reservoirs that the Secretary of the
Interior finds necessary to assure deliveries to comply with Articles III ( c) and III ( d) of
the 1922 Colorado River Compact, without impairment to the annual consumptive use in
the Upper Basin. The Secretary is required to make this determination after consultation
with the Upper Colorado River Commission and representatives from the three Lower
Division States, and after taking into consideration all relevant factors including, historic