The Colorado River:Interim Guidelines for Lake Powell and Lake Mead

National Integrated Drought Information System WorkshopOctober 1, 2008

Colorado River Basin

• Operation governed by the “Law of the River” including:– Colorado River Compact (1922)– Boulder Canyon Project Act (1928)– U.S. Mexican Water Treaty (1944)– Colorado River Storage Project

(1956)– Supreme Court Consolidated Decree

(1964 and following)– Colorado River Basin Project Act

(1968)• System operated on a “tight

margin”• Variable hydrology• Large amount of storage capacity

Short-termScheduling

Long-termPlanning

Mid-termOperations

Real-timeControl

Spatial Resolution/Time Horizon Operational Activity Decisions

Basin-wide over decades

Basin-wide over 1-2 years

Sub-basin over 4-6 weeks

Single project over 1-7 days

Operating Criteria and Guidelines

Annual Operating Plan

Water and PowerSchedules

Unit CommitmentEconomic Dispatch

Automatic Generationand Control

• In 2004, five years of unprecedented drought, coupled with increased water use, led to increased tensions among the Basin States

• There had 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 (through “equalization”)

Impetus for the Interim Guidelines

Interim Guidelines1 - A Robust Solution

• Operations specified through the full range of operation for Lake Powell and Lake Mead

• Encourage efficient and flexible water use and management in the Lower Basin through the Intentionally Created Surplus (ICS) mechanism

• Strategy for shortages in the Lower Basin2, including a provision for additional shortages if warranted

• In place for an interim period (through 2026) to gain valuable operational experience

• Basin States agree to consult before resorting to litigation1. Issued in Record of Decision, dated December 13, 2007; available at http://

www.usbr.gov/lc/region/programs/strategies.html

2. Mexico water deliveries are not directly effected by these guidelines

Lake Powell & Lake MeadOperational 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.

Colorado River Basin Storage (as of September 29, 2008)

Current StoragePercent

FullMAF

Elevation (Feet)

Lake Powell 60% 14.53 3627

Lake Mead 46% 12.00 1106

Total System Storage

57%* 34.10 NA

*Total system storage was 32.10 maf or 54% this time last year

Min Power Pool

3,490 ft

3,627 ft 14.53 maf(60% of Live Capacity)

3,370 ft Dead Pool Elevation

Lake Powell Capacity3,700 ft 24.3 maf

Dead Pool (1.9 maf)

Inactive Pool (4.0 maf)

Not to scale

72 ft

138 ft

As of Sep 29, 2008

3,636 ft

8 ft

3,575 ft

Lower Elevation Balancing Tier

Mid-Elevation Release Tier

3,525 ft

Equalization Tier

Upper Elevation Balancing Tier

Equalization Elevation(WY 2008)

Lake Powell Projected EOM Water Surface Elevation and StorageSeptember 24 Month Study

3500

3550

3600

3650

3700

Jan-

06

Mar

-06

May

-06

Jul-0

6

Sep

-06

Nov

-06

Jan-

07

Mar

-07

May

-07

Jul-0

7

Sep

-07

Nov

-07

Jan-

08

Mar

-08

May

-08

Jul-0

8

Sep

-08

Nov

-08

Jan-

09

Mar

-09

May

-09

Jul-0

9

Sep

-09

Nov

-09

Jan-

10

Ele

vatio

n (

fee

t) .

5

7

9

11

13

15

17

19

21

23

Sto

rag

e (

ma

f) .

Most Probable ElevationHistoric ElevationMost Probable StorageHistoric Storage

Lower SNWA Intake1,000 ft

1,106 ft 12.00 maf(46% of Live Capacity)

895 ft Dead Pool Elevation

Lake Mead Capacity1,219.6 ft 25.9 maf

Dead Pool (2.0 maf)

Inactive Pool (7.5 maf)

Not to scale

115 ft

As of Sep 29, 2008

1,145 ft

55 ft1,075 ft

Shortage Conditions1,050 ft

Surplus Conditions

Normal or ICS Surplus Conditions

Min Power Pool

15.9 maf

Lake Mead Projected EOM Water Surface Elevation and StorageSeptember 24 Month Study

1050.00

1070.00

1090.00

1110.00

1130.00

1150.00

1170.00Ja

n-06

Mar

-06

May

-06

Jul-0

6

Sep

-06

Nov

-06

Jan-

07

Mar

-07

May

-07

Jul-0

7

Sep

-07

Nov

-07

Jan-

08

Mar

-08

May

-08

Jul-0

8

Sep

-08

Nov

-08

Jan-

09

Mar

-09

May

-09

Jul-0

9

Sep

-09

Nov

-09

Jan-

10

Ele

vatio

n (

fee

t) .

11

12

13

14

15

16

17

Sto

rage

(m

af)

.

Most Probable ElevationHistoric ElevationMost Probable StorageHistoric Storage

The Colorado River:Interim Guidelines for Lake

Powell and Lake Mead

For further information:http://www.usbr.gov/lc/region