Transcript Colorado River Water Supply and 7 State Drought Plan Don Ostler Upper Colorado River Commission.

Colorado River Water Supply
and 7 State
Drought Plan
Don Ostler
Upper Colorado River Commission
The Colorado River Compact of
1922
• Divides the River into an Upper and Lower Basin
at Lee Ferry, Arizona
• Lower Division States – Az, Ca, Nv
• Upper Division States – Co, NM, Ut, Wy
• AZ, Nv, Ut and NM have lands in both basins
• 242,000 square miles drainage area
• Serves the Basin & Cheyenne, Denver, Colo.
Sprgs, Wasatch Front, Las Vegas, Phoenix,
Tucson, Southern California, Albuquerque
Upper Colorado River Commission
1922 Colorado River Compact
• Apportions 7,500,000 ac-ft/yr to both the
Upper and Lower Basins
• Lower Basin given the right to increase
consumptive use by 1,000,000 ac-ft/yr
Upper Colorado River Commission
1922 Colorado River Compact
• Provides that Mexico be supplied with
water, first from surplus over 16maf; and
borne equally by the Upper and Lower
Basins if no surplus
• Upper Basin shall not cause the flow at
Lee Ferry to be depleted below
75,000,000 ac-ft for any ten years
Upper Colorado River Commission
The Mexican Treaty of 1944
• Provides an annual delivery to Mexico of
1,500,000 ac–ft per year
• Provides an additional 200,000 ac-ft when
there is a surplus
• Allows the USA to reduce deliveries during
extraordinary drought in same proportion
as USA uses are restricted
Upper Colorado River Commission
Upper Colorado River Basin
Compact of 1948
• Division of Upper Basin water between
states
– 50,000 Ac-Ft to Arizona
– 51.75% Colorado
– 23.00% Utah
– 14% Wyoming
– 11.25% New Mexico
Is the water really there that was
assumed by the 1922 compact
drafters???
• How do their assumptions on available
supply compare to the 100+ years of
record???
• Should we rely on the current 100+ years
of record?
Upper Colorado River Commission
Hydrologic Determination
(Safe Annual Yield)
• Upper Basin Safe Annual Yield = 6.04 MAF
• Upper Basin consumptive uses = 5.76 MAF
(Colorado share = 2.95 MAF)
• Assumes a 6% chance of shortage
• 1922 Compact assumes 7.5 MAF/yr available
?????????
Upper Basin Consumptive Use
Source: Consumptive Uses and Losses Report - USDOI
6000
AF x 1000
5000
4000
3000
2000
1000
Annual Water Consumed
Linear (Annual Water Consumed)
19
7
19 1
7
19 2
1973
7
19 4
7
19 5
1976
7
19 7
7
19 8
1979
8
19 0
8
19 1
1982
8
19 3
8
19 4
1985
8
19 6
8
19 7
1988
8
19 9
9
19 0
1991
9
19 2
9
19 3
1994
9
19 5
9
19 6
1997
9
19 8
9
20 9
00
0
Year
Upper Colorado River Commission
Provided by: Eric Kuhn CRWCD
CURRENT WATER SUPPLY
CONDITIONS
– Major CRSP Reservoir Storage 6/30/06
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Reservoir
Fontenelle
Flaming Gorge
Blue Mesa
Navajo
Lake Powell
Upper Basin Tot.
Inflow %
60
54
53
21
53
Storage%
83
83
97
86
52
60
THE DROUGHT
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5 years of extreme drought (2000-2004)
Unregulated inflows 62,59,25,51,49 %
Powell fell to 33% capacity; 145 ft< full
2005 - 105% of ave. Powell + 31 feet
2006 – 73% of ave.
Is the drought over???
Basin States Drought Plan
• Shortage plan for the lower basin
– 200, 400, 600KAF shortage…..More??
• Coordinated operations of Powell and
Mead
– Equalization
– Elevation targeted releases
– Elevation targeted balancing of contents
– Reduce curtailment and shortage risk
Basin States Drought Plan
• Improve system efficiency
– Excess delivery to Mexico
– More regulatory storage/canal lining
• Extraordinary Conservation – water bank
– Fallowing farmland
• Augmentation projects
– Desalination projects
– Importation
Basin States Drought Plan
• Non-Colorado River system water
exchange process
– Non-Colorado River water provided to one
state in lieu of diverting Colo. R. water
– Providing state allowed to increase their
diversion of Colo. R. water by same amount
• Accounting process
Questions of Science, Certainty,
Risk, Politics and Urgency
• What amount of water should we plan on?
• What level of shortage risk shall we base
our usage plan on?
• How do we use less precise forms of data
in our water planning
• What weight do you assign to public
acceptability of a plan?
Upper Colorado River Basin
Compact of 1948
• Divides Upper Basin water between States
– 50,000 ac-ft to Arizona
– 51.75% to Colorado
– 23.00% to Utah
– 14.00% to Wyoming
– 11.25% to New Mexico
51.75% of 7.5maf = 3.86 maf/yr ??? Colorado
Upper Colorado River Commission
Hydrologic Determination
(Safe Annual Yield)
• Upper Basin Safe Annual Yield = 6.04MAF
• Upper Basin Consumptive Uses =
5.76MAF (Colorado share = 2.95MAF)
• Assumes 6% chance of shortage
• 1922 Compact Assumed 7.5 MAF
available??????????????