Dennis Kubly

Upper Colorado RegionSalt Lake City, Utah

Selective Withdrawal on

Glen Canyon Dam

TWG Update Jan 26, 2006
Glen Canyon Dam and Powerp

• Concrete Ar• 710 feet high• 27 MAF Sto• Eight Franci• 1,320 MW c

RECLA
Pre- and Post-Dam Water Temperature 

-5

05

1015202530

0 50 100 150 200 250 

Time (days)

Temperature (OC )

Pre-DamPost-Dam

Jan Feb Mar Apr May Jun Jul Aug Sep Oct 
REMOVE JEOPARDY

Develop a program

of 

experimental flows

Implement a selective

withdrawal program and 

determine feasibility

Develop a manag

for the

Little Colorado 

Determine responses of

endangered fish

to temperatures and flows

Establish a second spawning

aggregation of humpback chub

below Glen Canyon Dam

Develop actions to help ensure 

continued existence of

razorback sucker

Elements of the Reasonable and Prudent Altern

RECLA
Uncontrolled 

OverdrawFixed Inlet

Overview

Operating Range/Minimum 

Reservoir Elevation: 30’/3670’

Field Cost Estimate $13.5M
T

e

m

p

e

r

a

t

u

r

e

(

C

)

05

10152025

GlenCanyonDam

LittleColoradoRiver

HavasuCreek

Conditions below Glen Canyon Dam with 

TemperaturePreferred byHumpbackChub

RiverTempIncreTempContr
What Could go Wrong?

• Entrainment of non-native fish from L

Powell

• Modification/degradation of food base• Increase in parasites and diseases• Increase in non-native fish competitor

predators

RECLA
Probability of Future Lake Powell Elevation Exceedances in Ju

0

0.20.40.60.8

1

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

2022

2024

2026

2028

2030

2032

2034

2036

2038

2040

2042

2044

2046

Y

Probability of Occu rren ce 
Alternative 4: Release Temperature

Modify Intakes 

05

10152025

1/1/92 7/1/92 12/31/92 7/1/93 12/31/93 7/1/94 12/31/94 

R e le a s e T e m p erature ( C ) 2 of 8 structures 3 of 8 structures

4 of 8 structures 8 structures
5

10152025

1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 

Water Temp (C)

Elev 3570'Elev 3560'Elev 3550'Elev 3540'Elev 3530'Elev 3520'

Modeled Glen Canyon Dam Release Tem

No Action Release Temperature 

05

10152025

January March May July September Novemb

Release Water Temperature (C)
External Frame

Operating Range/ Minimum Reservoir Elevation: 190’/3510’Field Cost Estimate $59M

Overview
Projected Release Temperature from Two TCD External 

05

10152025

January March May July September Novemb

Release Water Temperature (C)Reservoir elevation 3550 ft Reservoir elevation 3700ft
Statistical Percentiles Following Historic Record

Powell Pool Elevation

3,4503,5003,5503,6003,6503,7003,750

1964 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 2023 2028 2033 2038 2043 

Year

Powell Pool Elevation (ft)

Historic 10% 5Max H Max 10 MMin H Min 10 M
Controlled 

Overdraw

Or

Stacked Frame 

Overview

Operating Range/Minimum 

Reservoir Elevation: 70’/3600’

Field Cost Estimate $21-36M
Projected Release Temperature from Two TCD Controlled Over

05

10152025

January March May July September Novemb

Release Water Temperature (C)

Reservoir elevation 36

Reservoir elevation 3700ft 
Probability of Operation

El. 3700 to El. 3575 90%El. 3670 to El. 3600 45%El. 3670 to El. 3590 50%El. 3700 to El. 3600 75%El. 3700 to El. 3510 99%

Percent of Time that TC

Operated Over the 10 Y

Period*

Operational Range-Reservoir 

Water Surface Elevations

*During months of May through October. Based on Riverware mode
Projected Release Temperature from Two TCD Units and No 

05

10152025

January March May July September Novembe

Release Water Temperature (C)
Lake Powell Release 2006 Temperature Scenarios

68

10121416182022

1/1/2006 2/20/2006 4/11/2006 5/31/2006 7/20/2006 9/8/2006 10/28/2006 12/1

Date

Temp, °C