WSPC05293

• File Number: 8283.200
• Description: Colorado River - Colorado River Computer Models - CRDSS
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 10/14/1994
• Author: Various
• Title: CRDSS - Colorado River - General - Newspaper Articles-Press Releases - October through December 1994
• Water Supply Pro - Doc Type: News Article/Press Release

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DEC-03-1993 13:49
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FROM USEPA REGION 8 OEA

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Should the region experience only a moderate Increase in temperllture (20C) and 11
large Increa~e in precipitatIon (20%), one would see roughly a 20 percent increase
in mean annual runoff, a 30 to 60 percent increase in storage and a 40 percenj
Increase in power production, .

"Normally, Lake Powell never falls below the level needed to generate hydr~lectrkity. If
nverage runoff decreases b~ only 5 percent, hydroelectric generation at Glen Canyon Da~
wlll &top 20 percent of the lImll, If average runoff drops by 20 percent, then hydroelectricity
ieneration drops 60 percent. These drops would have dramatic effects across the
Southwest," accordIng to Peler Glefck. I

,
Dell\'crles or Water to the Central Arizona Project (CAP) ;
. Under current conditIons annual deliveries of water to the Central Arizona Project'
(CAP) are expected to equal or exceed scheduled dellvenes 60 percent of the time, while'
deliveries fait to their minimum level 20 percent of the time. Normally, dellverles to CAP:
never fall below the minimum of 451 thousand acre-feet per year, which is the level at!
which mUl'dctpal and industr!!!! usage wo\;ld be impaIred, Even slight decrea~es in runoff,1
however, have a major impact on CAP water deHveries, . A permanent reduction in!
Colorado RjYer average runoff of only 5 percent would cause the frequency of deliveriesi
to CAP to fall substantially, so that full supplies are only delivered in 35 pere,ent of the,
years, Moreover, under thi., scenario, CAP recejves only the mlnlm\ll1:l delivery SO percent1j
of the years.

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Under current conditions, Mexico receIves IS15 thousand acre.feet per year. If,
average annual runoff drops 10 percent, the allocation model delivers to Mel(ico less than
their full treaty amount fn 5 percent ot the years; under the .20 percent runoff scenarIo,
Mexico experiences Colorado River shortages 35 percent of the time. Although the delivery
data suggest that M exfco Is affected only in extreme cases, decreased !lows in the lower I
halin willlesd to poor quallty of water delivered to Mexico almost all the time, In fact,:
Il.lllower basin users would suffer a significant decline in water quality. I

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Deliveries or Water to MexIco

For free coplcs of fhe full report, Rlease COlllacf the U.S. E"viromnental Protection Agency
publica/lortS distribution: Ordm can be fa;;ed to [phone]. Phone orders go to ($13)
891.6561. The repM Iltle is; 'The Colorado River Easln and CUmutic Change.. The report
number is EPA. 1230.R.93.009.