Download - May 1 Water Talks - Dr. Terry Fulp
The Colorado River and its Future
San Diego County Water Authority
Water Talks
May 1, 2012
The Colorado River and its Future Outline
• Background
• Coordinated operation of
Lake Powell and Lake
Mead
• Current state of the system
• Looking ahead
Colorado River Basin Background
7.5 maf
7.5 maf 2.8 maf
4.4 maf
0.3 maf
14 %
51.75 % 23 %
11.25 %
0.050 maf
1.5 maf
Summary Points:
• System is over-allocated
• Hydrology is highly variable and storage capacity is critical
• System is operated on a tight margin
Historical Colorado River Water Supply & Use
(Annual)
Major Upper
Basin
Reservoirs
Glen Canyon
Aspinall
Flaming Gorge
Navajo
Upper
Basin
Hoover Dam
Major Lower Basin Reservoirs
Davis Dam
Parker Dam
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
110%
Pe
rce
nt
of
Ca
pac
ity
January 1937 - March 2012
Lake Powell and Lake Mead Percent of Live Capacity
Mead Percent of Capacity Powell Percent of Capacity
During the 2000's drought, Lake Powell declined to elevation 3,555.1 ft, or 33% capacity, in April 2005
During the 2000's drought, Lake Mead declined to elevation 1,081.9 ft, or 38% capacity, in November 2010
Both reservoirs began WY 2000 at 95% capacity
Lake Mead began to fill in April 1936 and first filled to 100% capacity in July 1941
Lake Powell began to fill in June 1963 and first filled to 100% capacity in June 1980
During the 1950's drought, Lake Mead declined to a low elevation of 1,083.2 ft, or 40% capacity, in April 1956
Water Budget at Lake Mead
Inflow = 9.0 maf (release from Powell + side inflows)
Outflow = - 9.6 maf
(AZ, CA, NV, and Mexico delivery
+ downstream regulation and gains/losses)
Mead evaporation losses = - 0.6 maf
Balance = - 1.2 maf
Given basic apportionments in the Lower Basin, the allotment to Mexico, and an 8.23 maf release from Lake Powell, Lake Mead storage declines about 12 feet each year
Interim Guidelines for Operation of Lake
Powell and Lake Mead
• Key provisions:
– Operation for Lake Powell and Lake Mead is specified throughout the full range of operation
– Strategy for shortages in the Lower Basin is specified, including a provision for additional shortages if warranted
– Mechanism (Intentionally Created Surplus or ICS) is established to encourage efficient and flexible water use in the Lower Basin
• In place for an interim period (through 2026)
• Do not include provisions for Mexico
• ICS may be created through a variety of measures
• There is a 5% “system assessment” when ICS is created (except for system efficiency projects)
• ICS balance subject to 3% annual evaporation loss each year after creation
• Delivery of ICS may occur in years after creation
Intentionally Created Surplus (ICS)
Warren H. Brock Storage Reservoir
Colorado River Basin Storage (as of April 29, 2012)
Current Storage Percent
Full MAF
Elevation
(Feet)
Lake Powell 64% 15.51 3,636
Lake Mead 54% 14.00 1,124
Total System
Storage* 62% 37.19 NA
*Total system storage was 31.57 maf or 53% this time last year
2012 Upper
Colorado
Forecasted
Apr–Jul Inflow1 as of April 16
Flaming Gorge – 80%
Blue Mesa – 47%
Navajo – 57%
Lake Powell – 46%
1 Percent of average is based on the period of record from 1981-2010.
Water Year Snowpack and Precipitation as of April 30, 2012
Source: CBRFC
Chart developed with
Snotel data as of
4/30/2012
Colorado River
Basin above
Lake Powell
Water Year
Precipitation1
(year-to-date)
77%
Current
Snowpack1
29%
1 Percent of average is based on the period of record from 1971-2000.
State of the System (Water Years 1999-2012)1
109%
62% 59%
25%
52% 49%
104%
71% 70%
102%88%
73%
139%
61%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0
5
10
15
20
25
30
35
40
45
501
99
9
200
0
200
1
200
2
200
3
200
4
200
5
200
6
200
7
200
8
200
9
201
0
201
1
201
2
Pe
rce
nt C
ap
ac
ityV
olu
me
in
MA
F
End of Water Year
Unregulated Inflow into Lake PowellPowell-Mead Storage and Percent Capacity
Powell and Mead Storage (MAF) Unregulated Inflow into Powell (MAF) Powell and Mead Percent Capacity
1 Values for water year 2012 are projected. Unregulated inflow is based on the latest CBRFC forecast. Storage and percent capacity are based on the April 2012 24-Month Study.
2 Percentages at the top of the light blue bars represent percent of average unregulated inflow into Lake Powell for a given water year. Water years1999-2011 are based on the 30-year average from 1971 to 2000. Water year 2012 is based on the 30-year average from 1981-2010.
2
Historical and Projected Colorado River Water
Supply & Use
• Study Objectives
• Assess future water supply and demand imbalances through 2060
• Assess risks to basin resources
• Develop/evaluate options and strategies for resolving imbalances
• Email: [email protected]
• Website:
http://www.usbr.gov/lc/region/programs/crbstudy.html
• A planning study – will not result in any decisions, but will provide the technical foundation for future activities
Colorado River Basin Water Supply and
Demand Study
The Colorado River and its
Future
For further information:
http://www.usbr.gov/lc/region