WSPC12586

• File Number: 8210.215
• Description: Colorado River Basin Organizations-Entities - Colorado River Workgroup
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 5/13/2004
• Author: Unknown
• Title: Proposed Modeling Assumptions - Drought Management Assessment - Scenario Number 1 - Draft - 05-13-04
• Water Supply Pro - Doc Type: Report/Study

000874

Proposed Modeling Assumptions
Drought Management Assessment
Scenario #1

1) Future hydrology will be generated from the historic record of natural flows (from 1906
through 1995) using the hldex Sequential Method. 90 simulations will be run.

2) Reservoir starting conditions (all system reservoirs) are based on projected water level
elevations for January 1, 2005, and the model will be run through 2074.

~

3) Future water demands for Lower and Upper Basin diversions::will ~ based on depletion
projections prepared by the Basin States and published inNiqllroe II, Appendix G, of the
Final Environmental Impact Statement for the Impl~tio~eement, hladvertent
Overrun and Payback Policy, and Related Federal ActiOits (SIA~), with the
exception of the Imperial Irrigation District (IID~achella Wat'ei'Vistrict
(CVWD), and the Metropolitan Water Distri~South~ California ~).
Depletion schedules under normal conditiQris fOr lID, MWn, and C~e as
specified by the Colorado River Water Delivery ~~tExhibit B) agO will include
paybacks for 2001 and 2002 (Exhibit C). Reference~; tlti all other depletion schedules are
as follows: - -
a) Future water demands under no~ditions for ~erJ..ower Basin diversions,
SIA-FEIS, Volume II, Appendix lt~ent A. ~=--
b) Future water demands under surpldicond~alll:iOwer Basin diversions, SIA-
FEIS, Volume II, ~dix G, A~ C. _-
c) Future water ~~l Upper Btf!in diversitfns, SIA-FEIS, Volume II,
Appendix ~chmeti€i. ~
;7.'. --- = . ~.... .
- - -
- - ~
- --. -
4) Under normal condi~~~~l).Bcheifule for the Mexican delivery will be set to
1.572 ~?'~addi~mi1 72 k~ Mexico's basic apportionment reflects the
av~ over-detl\eies to ~~o for the period 1964-2003 (excluding years when there
~ood control teiises on~orado main stem or Gila River). UnderLake Mead
nooit~trol release cQiWitionslfe., a flood control surplus), Mexico will receive up to
1.7 maG- c, ...... ;;

5) Bypasses to thi:if:ien~de Santa Clara in Mexico will be assumed to be 109,000 acre-
feet per year (th~_rical average from 1990- 2003) and will not be counted as part of
the Treaty delive15" Replacement of the bypassed water will not be assumed to occur in
the future.

6) Upper Basin reservoir operating rules (excluding Lake Powell) will be those used in the
SIA-FEIS. Under those rules, operation of reservoirs above Lake Powell is independent
of Lake Powell's operation.

7) Lake Mohave and Lake Havasu will be operated in accordance with their existing rule
curves.

Draft: Subject to Change

1

Last Revision: May 13, 2004