Colorado River Update

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Colorado River Update Riverside County Water
Symposium May 1, 2008
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Colorado River Update

• Overview of Basin and Basin Hydrology
• Overview of the New Interim Guidelines
• Current and Projected System Conditions
• Update on Some Key Activities

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• Colorado River Basin
• 16.5 million acre-feet (maf)
  allocated annually
• 13 to 14.5 maf of consumptive use annually
• 15.1 maf average annual natural inflow into
  Lake Powell over past 100 years
• 60 maf of storage
• Inflows are highly variable year-to-year
• Operation governed by the Law of the River

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Natural FlowColorado River at Lees Ferry Gaging
Station, ArizonaCalendar Year 1906 to 2005
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State of the System (1999-2008)
Based on April 24 Month Study
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Colorado River Drought

• 2000-2007 was the driest 8-year period in the
  100-year historical record
• Tree-ring reconstructions show more severe
  droughts have occurred over the past 1200 years
  (e.g., drought in the mid 1100s)
• Projected 2008 April through July runoff forecast
  122 of average (as of April 14, 2008)
• Not unusual to have a few years of above average
  inflow during longer-term droughts (e.g., the
  1950s)

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Annual Natural Flow at Lees FerryTree-ring
Reconstruction (Meko et al., 2007)25-Year
Running Mean
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Potential Impacts of Climate Change

• Wet get wetter and dry get drierand the
  Southwest likely to get drier
• Wide range of projected declines in Colorado
  River average inflow (0 to 40)
• Lots of research on-going (and needed)

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Impetus for the Interim Guidelines

• Eight years of unprecedented drought coupled with
  increased water use
• To date, there has never been a shortage in the
  Lower Basin and there were no shortage guidelines
• Operations between Lake Powell and Lake Mead were
  coordinated only at the higher reservoir levels
  (equalization)
• Note A U.S. action only Mexico deliveries in
  accordance with Treaty

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Interim Guidelines1 - A Robust Solution

• Operations specified through the full range of
  operation for Lake Powell and Lake Mead
• Encourage efficient and flexible use and
  management of Colorado River water through the
  ICS mechanism
• Strategy for shortages in the Lower Basin,
  including a provision for additional shortages if
  warranted2
• In place for an interim period (through 2026) to
  gain valuable operational experience
• Basin States agree to consult before resorting to
  litigation

• Issued in Record of Decision, dated December 13,
  2007 available at http//www.usbr.gov/lc/region/p
  rograms/strategies.html
• Mexico water deliveries are not directly effected
  by these guidelines

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Lake Powell Lake Mead Operational Diagrams
1 Subject to April adjustments that may result in
balancing releases or releases according to the
Equalization Tier. 2 These are amounts of
shortage (i.e., reduced deliveries in the United
States). 3 If Lake Mead falls below elevation
1,025 ft msl, the Department will initiate
efforts to develop additional guidelines for
shortages at lower Lake Mead elevations.
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Projections of Lower Basin ShortagesNo Action
(FEIS) New Interim GuidelinesProbability of
Occurrence of Any Amount
No Action (FEIS)
New Guidelines
Probability of Occurrence
Year
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2008 Upper ColoradoProjected AprJul Inflow
Flaming Gorge 75
Blue Mesa 147
Navajo 155
Lake Powell 122
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Colorado River Basin Storage (as of April 27,
2008)
Total system storage was 33.14 maf or 56 this
time last year
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Lake Powell Capacity
3,700 ft
24.3 maf
Equalization Tier
107 ft
3,636 ft
Equalization Elevation (WY 2008)
Upper Elevation Balancing Tier
43 ft
3,593 ft
11.12 maf (46 of Live Capacity)
3,575 ft
103 ft
Mid-Elevation Release Tier
3,525 ft
Lower Elevation Balancing Tier
Min Power Pool
3,490 ft
Inactive Pool (4.0 maf)
Dead Pool Elevation
3,370 ft
Dead Pool (1.9 maf)
Not to scale
As of April 27, 2008
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Lake Mead Capacity
1,219.6 ft
25.9 maf
Surplus Conditions
109 ft
15.9 maf
1,145 ft
Normal or ICS Surplus Conditions
1,111 ft
12.52 maf (48 of Live Capacity)
61 ft
1,075 ft
Shortage Conditions
Min Power Pool
1,050 ft
Inactive Pool (7.5 maf)
Lower SNWA Intake
1,000 ft
Dead Pool Elevation
895 ft
Dead Pool (2.0 maf)
Not to scale
As of April 27, 2008
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Current Activities

• On-going cooperation with Mexico
• Yuma Desalting Plant Alternatives
• Quagga Mussels
• Drop 2 Storage Reservoir
• Title XVI

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Colorado River Update For further
information http//www.usbr.gov/lc/region