HYDROSPHEREResource Consultants

July 30, 2004

Severe and Sustained Drought

29th Colorado Water Workshop

The Project

• The beginnings

• Objectives – Hydrology– Impacts– Responses

What is a drought?

• Hydrologic drought– Consecutive flows below the mean flow– Depends on mean– Mean depends on period of record

• System drought– Low-flow conditions that cause distress– Depends on storage, deliveries, policy

The Drought

• System context is c. 1992

• 38-year scenario (1579-1616)

• Re-arranged to increase onset intensity

• Low flow period, recovery period

• 2000 - 10000–year return interval

• “Probable extreme drought”

SSD Drought Trace

SSD Scenario vs Natural Order

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Annu

al Flo

w, m

af Natural Order

Baseline

Impacts

• Reservoir storage

• Water availability

• Power and energy

• Water quality

• Social

• Economic

• Environmental

Reservoir Contents

Powell and Mead ContentsSSD Drought

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Conte

nts, m

af

Powell

Mead

Water Availability

DepletionsSSD Drought

0

1

2

3

4

5

6

7

8

9

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Deple

tions

, maf

Upper Division

Lower Division

Energy

System Hydropower GenerationSSD Drought

0

2000000

4000000

6000000

8000000

10000000

12000000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Gene

ration

, mWh Baseline

Water Quality

Salinity Below Hoover DamSSD Drought Baseline

0

200

400

600

800

1000

1200

1400

1600

1800

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Salin

ity, p

pm

Mitigation

• Actions identified in gaming

• Intrastate actions

• Interstate actions– Reverse equalization– Relaxation of compact

Lee Ferry Deliveries

Lee Ferry Depleted FlowsSSD Drought Scenarios

5

5.5

6

6.5

7

7.5

8

8.5

9

9.5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Annu

al Flo

w, m

af

Baseline

Scenario 1

Scenario 2

Powell

Lake Powell ContentsSSD Scenarios

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Cont

ents,

maf

Baseline

Scenario 1

Scenario 2

Mead

Lake Mead ContentsSSD Scenarios

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Conte

nts, m

af

Baseline

Scenario 1

Scenario 2

Depletions

DepletionsSSD Drought Scenarios

0

1

2

3

4

5

6

7

8

9

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Deple

tions

, maf

Upper Baseline

Lower Baseline

Upper Scenario 1

Upper Scenario 2

Lower Scenario 1

Lower Scenario 2

You are hereLee Ferry Natural Flows

SSD Drought vs. Current Conditions

200420032002

20012000

19991998

1997

1996

1995

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Annu

al Flow

, maf

Baseline

Current

Powell: SSD vs. CurrentLake Powell Contents

SSD Drought vs. Current Conditions

2004

2003

2002

2001

2000

199919981997

19961995

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Conte

nts, m

af

Baseline

Current

Lee Ferry: SSD vs. Current

Lee Ferry Depleted FlowsSSD Drought vs. Current Conditions

2004200320022001

2000

1999

19981997

1996

1995

0

2

4

6

8

10

12

14

16

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Annu

al Flo

w, m

af Baseline

Current

Mead: SSD vs. CurrentLake Mead Contents

SSD Drought vs. Current Conditions

2004

20032002

2001

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Drought Year

Conte

nts, m

af

Baseline

Current

The Wisdom of Chairman Yogi

• It’s like déjà vu all over again.

• It ain’t over till it’s over.

• Making predictions is hard, particularly about the future.

• The future ain’t what it used to be.

Upper Colorado River Compact Issues• Quantification of states’ depletions

• Quantification of PPRs

• Quantification and allocation of channel losses

• Quantification and allocation of reservoir evaporation

• Overdrafts

Intrastate Issues

• Quantification of entitlement

• Quantification of PPRs

• Avoidance of overdrafts

• Administration of curtailment

• Mechanisms for Subordination/Offsets

Modeling Issues

• Colorado River Compact

• Upper Colorado River Compact

• Mexico Treaty

• Intrastate rights

• Present Perfected Rights

• Physical models

• Probabilistic Forecasting