Summary Report ‎(Working Draft)‎ Modeling of Reservoir Management Strategies for Lakes Powell and Mead December 2005

• Description: Summary Report ‎(Working Draft)‎ Modeling of Reservoir Management Strategies for Lakes Powell and Mead December 2005
• State: CO
• Title: Summary Report ‎(Working Draft)‎ Modeling of Reservoir Management Strategies for Lakes Powell and Mead December 2005
• Water Supply Pro - Doc Type: Meeting

Modeling Results for
Colorado River Basin States' Modeling of
Colorado River and Reservoir Management Strategies
Powell Normal Operations
1) Lake Powell follows a forecast driven, spring runoff operation (January through
July) that attempts to fill Lake Powell to a July target storage (23.822 MAF or
500 KAF of space) and a fall operation (August through December) that
attempts to draw down the reservoir to a December target storage (21.900 MAF
or 2.422 KAF of space). Lake Powell's spring and fall operational release is
constrained in each month to be within a minimum and maximum range. The
range is set to 390 KAF per month and 1,500 KAF per month respectively,
reflecting the current limits on release rates of 6,500 cfs and 25,000 cfs.
2) Lake Powell's operation satisfies a minimum objective release to the Lower
Basin of 8.23 MAF over each water year (October through September) if those
releases do not result in Powell's elevation being below 3370 feet (top of dead
pool). At times when Lake Powell does not have enough water to meet the
minimum objective release, a mass balance is used to determine how much
water is released (inflow plus water in storage above dead pool minus losses).
3) Lake Powell makes equalization releases (in excess of the minimum objective
release) if the EOWY content in Lake Powell is forecasted to be greater than
Lake Mead's EOWY content and the 602(a) storage criterion is met. The 602(a)
storage value is computed as documented in the ISG -FEIS, Volume II,
Attachment J, with the addition that no equalization will occur for the years up to
and including 2016 if Lake Powell is projected to be below 14.85 MAF
(elevation 3630 feet) on September 30, per the Final Environmental Assessment
Adoption of an Interim 602(a) Storage Guideline.
4) Beach/Habitat Building Flows (BHBF) are triggered as documented in the SIA-
FEIS.
Note: These assumptions are identical to those documented in the ISG -FEIS,
Volume II, Attachment J, with the following exceptions:
• In those studies, the minimum objective release was maintained if those
releases did not result in Lake Powell's elevation being below 3490 feet
(minimum power pool). However, when the minimum objective release
resulted in Lake Powell going below minimum power pool of elevation 3490
feet, releases from Lake Powell were adjusted in order to protect the
minimum power pool.
• The interim 602(a) storage criterion involving Lake Powell's elevation of
3630 feet was not used in those studies.