Page 1 

Glen Canyon Dam Technical Work Group 

Agenda Item Information 

June 24-25, 2014

Agenda Item 

Long-Term Experimental and Management Plan (LTEMP) EIS Update 

Action Requested 

 Information item only. 

Presenter 

Glen Knowles, Bureau of Reclamation (Reclamation) 

Previous Action Taken 

 Other 

December 2009: Secretary of the Interior Ken Salazar announced that the development of a 

Long-Term Experimental and Management Plan (LTEMP) for Glen Canyon Dam was 

needed. The Secretary emphasized the inclusion of stakeholders, particularly those in the 

Glen Canyon Dam Adaptive Management Program (GDAMP), in the development of the 

LTEMP. 

November 2011: Public scoping meetings were held in Phoenix, Flagstaff, Page, Salt Lake 

City, Las Vegas, and Denver. A webcast was also held to capture participation from those 

that could not attend in person. 

April 4-5, 2012: A public workshop was held in Flagstaff, AZ to receive feedback on the 

preliminary alternative concepts. 

April 30, 2012: The Secretary of the Interior responded to a recommendation from the 

AMWG by stating, “With respect to the report of the Socioeconomic Ad Hoc Group, I 

appreciate the comprehensive nature of the program and plan proposed, and the support of 

the AMWG for the implementation of these socioeconomic impact assessment studies. I am 

directing the interagency team for the Department of the Interior to communicate to the 

AMWG the specific studies and activities that should be prioritized for utilization as part of 

the ongoing National Environmental Policy Act process to develop a Long Term 

Experimental and Management Plan (LTEMP) for Glen Canyon Dam. The Technical Work 

Group can then identify information needs and research priorities not addressed through the 

LTEMP process so that the [Grand] Canyon Monitoring and Research Center can refine and 

develop a work plan.” 

August 30, 2012: Motion (moved by Larry Stevens and seconded by Ted Rampton): 

AMWG requests that the February 2013 AMWG meeting agenda include a detailed 

description of the LTEMP alternatives; time for discussion and identification of issues, 

questions, and concerns; and possible development of a recommendation from non-DOI 

AMWG members. 

Relevant Science 
LTEMP EIS, continued 

 Page 2 

Science and research completed since the GCDAMP was established will be used in the 

development of the EIS and assessment of impacts. 

Background Information 

The Department of the Interior (Department), through Reclamation and NPS, is preparing a draft 

EIS for adoption of the LTEMP for the operation of Glen Canyon Dam. The purpose of the 

proposed LTEMP is to utilize current, and develop additional, scientific information to better 

inform Departmental decisions and to operate the dam in such a manner as to improve and protect 

important downstream resources while maintaining compliance with the GCPA, the Law of the 

River, and the Endangered Species Act, among others, and to fully evaluate dam operations and 

identify management actions and experimental options that will provide a framework for adaptively 

managing Glen Canyon Dam over the next 15 to 20 years, consistent with the GCPA and other 

provisions of applicable Federal law. 

The presentation will review progress made since the last AMWG meeting in May 2014 including a 

review of the current set of draft alternatives, development of a hybrid alternative, and the schedule 

for completion of the LTEMP Draft EIS. 
Glen Canyon 

LTEMP EIS Up

Glen Knowle

GCDAMP Technical W

June 24, 201
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Overview• Alternatives• Modeling and SDM

• Emerging Hybrid Alternative• Experimental Design

• Schedule

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Alternatives Being Analyzed in EIS1. No‐Action Alternative (NA)2. Balanced Resource Alternative (BR)

3. Condition‐Dependent Adaptive Strategy (CDA)

4. Resource Targeted Condition‐Dependent Alternative 5. Seasonally Adjusted Steady Flows (SASF)

6. Year‐Round Steady Flows (YRSF)

• Note that BR, CDA & RTCD were modeled with several 

versions with various options turned on or off.
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Completion of Modeling and Structured Decision • The majority of the modeling for the LTEMP Draft EIS 

completed, but interpretation, quality checking and p

continues as well as other qualitative and quantitative 

• Structured decision making process has been comple

has provided input both to stakeholder views and to th

information for experimental design.

• A decision regarding a preferred alternative has not a

not be made based solely on the structured decision or the modeling results, but will also use the informatgathered in the context of many other important sour

information such as public comments, additional mod

results, empirical data review, qualitative analysis, and policy analysis.
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Multi‐criteria Decision Analysis

StakeholderFederal State Tribe 

JL USFWS AZDWR AZGFD SRP UAMPS CREDA Hopi Hualapai Navajo 

No Action 0.474 0.506 0.493 0.444 0.504 0.491 0.508 0.516 0.521 0.490 

Balanced Resource BR1 0.485 0.503 0.522 0.448 0.526 0.529 0.523 0.514 0.532 0.509 

BR2 0.460 0.441 0.470 0.408 0.536 0.550 0.542 0.470 0.482 0.470 

CDAS 1 0.599 0.537 0.487 0.500 0.480 0.444 0.452 0.565 0.582 0.524 

2 0.590 0.514 0.473 0.512 0.456 0.418 0.441 0.566 0.577 0.521 3 0.390 0.437 0.406 0.375 0.474 0.466 0.481 0.429 0.416 0.401 4 0.552 0.507 0.467 0.492 0.487 0.453 0.474 0.534 0.533 0.505 

RTCD 1 0.584 0.532 0.536 0.501 0.519 0.505 0.495 0.574 0.595 0.550 

2 0.577 0.537 0.545 0.510 0.498 0.479 0.476 0.581 0.605 0.557 3 0.414 0.489 0.509 0.416 0.507 0.513 0.504 0.481 0.488 0.474 4 0.557 0.541 0.549 0.506 0.517 0.499 0.497 0.568 0.587 0.556 5 0.412 0.483 0.499 0.411 0.489 0.494 0.485 0.476 0.485 0.465 6 0.424 0.499 0.518 0.420 0.515 0.526 0.506 0.485 0.495 0.477 

SASF 0.560 0.467 0.403 0.486 0.329 0.291 0.318 0.514 0.525 0.439 

YRSF 0.565 0.539 0.449 0.506 0.434 0.370 0.395 0.528 0.547 0.498 

Best performing alternative for this stakeholder's weightingsAlternative performs better than No ActionAlternative performs worse than No ActionWorst performing alternative for this stakeholder's weightings
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Desired Characteristics of a Hybrid Alternati• Performs well relative to all resource goals and objecti• Meets humpback chub recovery goals

• Increase and retain sediment• Maintain or increase the hydropower resource

• Performs well on recreation metrics• Performs well on other resource metrics (cultural, veg

etc.)

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Characteristics of an Emerging Hybrid Altern

Component NotesMonthly volumes RTCDDaily fluctuations 10x/9x with 8k cap 10x fluctuations Jun‐Aug, 9x fluctuati

of year. Maximum daily range of 8,000 

Proactive spring HFEs Yes Test (only in >10 maf year)

Spring HFEs Yes Limit to 45 K for 96 hr

Fall HFEs Yes More flexibility in duration, up to 336 

Rapid response HFE NoTrout management flows Yes Test and continue if performs well

Low summer flows Yes

Test in second 10 years if needed, adj

14 or 15 C for Jul, Aug, Sep (only in ye

temp is achievable based on release t

Mechanical removal of

trout

Yes Condition dependent

Load curtailment Yes before,

test after

Load curtailment post‐HFE would occ

month of HFE only

Vegetation control Yes Adaptive vegetation restoration activi

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Review of Sediment Results

Preliminary Results—Do Not Cite or Distribute

• Hydrology is biggest driver, as for all resources• Frequency of HFEs and fluctuation levels are also importan• Low summer flows move water to April which causes great

sediment transport in the spring.

– Low summer flows do transport less sediment in the summer but 

completely compensate for the sediment lost in Spring.

– CDAS1 (w/o LSF) retains approximately 100 ktons more than CDAS

end of water year

– Approximately the same difference in sediment transport betwee

RTCD2

• TMFs have little to no impact on SLI. There is little effect on 

especially by end of year

• Load curtailment has increased SMBI by 9 kton (annual diff

RTCD)

Preliminary Results—Do Not Cite or Distribute 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Screening Tool Estimates of Sediment Transport to SepFluctuation and Monthly Volume Effects

Preliminary Results—Do Not Cite or Distribute

Annual Sediment

Transport (MT)

Annual Sedi

Transport (%

Monthly

Pattern

Fluctuation

Level

(high/low

demand) 8.23 maf 12 maf 8.23 maf 

CDAS 7/7 321,111 1,944,581 89.6% 

RTCD 7/7 271,883 1,794,444 75.9% RTCD 10/9/8k cap 324,063 1,807,467 90.4% RTCD 12/10 361,083 2,065,655 100.8% 

MLFF 5K, 6K, 8K 358,266 1,858,317 100.0% 

Preliminary Results—Do Not Cite or Distribute 

Lower sediment transport than original CDAS and RTCD
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Review of Hydropower Results• Differences can be tied to frequency of HFEs and fluct

levels

• Value of Generation: RTCD1 produces $4M/year more 

value than CDAS1

• Value of Capacity: RTCD1 has $4.9M/year more capaci

than CDAS1

• Both RTCD and CDAS include 2,500 cfs down ramp rate 

an improvement relative to No Action (was 1500 cfs in 

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Screening Tool Estimates of Hydropower Value to Sepa

Fluctuation and Monthly Volume Effects

Preliminary Results—Do Not Cite or Distribute

Annual Hydropower

Value ($M)

Annual Hydropo

(%MLFF

Monthly

Pattern

Fluctuation

Level

(high/low

demand) 8.23 maf 12 maf 8.23 maf 

CDAS 7/7 210 305 97.0% 

RTCD 7/7 210 305 97.2% RTCD 10/9/8k cap 214 306 99.1% RTCD 12/10 216 310 99.8% 

MLFF 5K, 6K, 8K 216 307 100.0% 

Preliminary Results—Do Not Cite or Distribute 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Review of HBC Results

Preliminary Results—Do Not Cite or Distribute

• Biggest factors affecting the number of chubs in altern

were steady flows, TMFs or frequency of HFEs

• Hydrology (wet vs. dry) makes more difference to trou

production than does the differences between most a

• Hybrid alternative should perform better for HBC than 

comparable to CDAS1 and RTCD1. Performs better tha

YRSF for HBC

Preliminary Results—Do Not Cite or Distribute 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Lowest Adult HBC pop. (x1,000)

NA BR1 BR2CDAS1CDAS2CDAS3CDAS4RTCD1RTCD2RTCD3RTCD4RTCD5RTCD6

05

1015

Minimum Adult HBC population size (x1000)

LSF LSF LSF 

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Fluctuation levels• 10x/9x/8k cap explanation• 10 = a 10x factor of monthly volume (in kaf) to get ma

daily change (in cfs)

In a 700 kaf month, maximum daily change = 7000 cfs

This factor applies to June, July and August.

• 9 = a 9x factor for the other 9 months of the year• 8k cap = a maximum daily change of 8000 cfs, which is 

as current MLFF constraint.
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Comparison of RTCD 10/9 8k cap with MLFF

8.23 maf year

RTCD with 10/9 with 8k max MLFF

MonthlyVolume (kaf)

Mean dailyflow Daily Change

MonthlyVolume (kaf)

Mean daily

flow Daily Change

October 643 10451 5783 600 9758 6000 November 642 10781 5774 600 10083 6000 December 716 11643 6443 800 13011 6000 January 781 12707 7032 800 13011 6000 February 691 12449 6222 600 10804 6000 March 730 11870 6569 600 9758 6000 April 650 10922 5849 600 10083 6000 May 672 10935 6052 600 9758 6000 June 704 11829 7039 650 10924 6000 July 767 12471 7668 850 13824 8000 August 659 10721 6592 900 14637 8000 September 575 9668 5177 630 10588 6000 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Comparison of RTCD 10/9 8k cap with MLFF

12 maf year

RTCD with 10/9 with 8k max MLFF

MonthlyVolume (kaf)

Mean daily

flow Daily Change

MonthlyVolume (kaf)

Mean dailyflow Daily Change

October 643 10451 5783 600 9758 6000 November 642 10781 5774 600 10083 6000 December 716 11643 6443 800 13011 6000 January 1282 20858 8000 1000 16263 8000 February 1135 20435 8000 800 14405 6000 March 1198 19484 8000 900 14637 8000 April 1067 17929 8000 1000 16806 8000 May 1104 17950 8000 1100 17890 8000 June 1155 19417 8000 1200 20167 8000 July 1259 20471 8000 1400 22769 8000 August 961 15632 8000 1500 24395 8000 September 839 14097 7549 1100 18486 8000 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Benefits of Hybrid Alternative Relative to Original AlterConsidered• Blends multiple alternatives that were weighted highly by a 

variety of stakeholders in structured decision analysis proce

• Uses the monthly volume pattern of RTCD that more closel

power demand to improve hydropower performance and sconservation

• Represents an improvement over CDAS and RTCD in terms 

sediment transport and conservation

• Preserves beneficial effects of TMFs on humpback chub nu

• Tests a variety of condition‐dependent elements to improv

and humpback chub conservation

• Maintaining an 8000 cfs fluctuation cap has benefits for sed

recreation

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Elements of an Experimental Design• For all experiments, identify:

– Hypotheses being tested

– Design of monitoring component

– Adaptive response to information generated by experiment th

and easy to adapt to new information

– Implementation of multiple tests and avoidance of confoundin

the extent practicable

– Focus is on management tools as a suite as opposed to a focus 

separating out effects of individual treatments

– Continued monitoring for unintended/unexpected results and 

off‐ramps as needed

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Timeline• Post Modeling Discussions

– Hybrid Alternative Components

– Experimental Design– Peer Review

• Preliminary Draft #1 to cooperators and tribes – end of July

– No preferred alternative

– Tribes to provide input, others use as informational

• Preliminary Draft #2 to cooperators, tribes and GCMRC – end of 

– Plan to have a preferred alternative

– Will include tribal input

• Public Draft – end of October

– Will include full hydropower and ratepayer analysis
Glen Canyon 

LTEMP EIS Up

Glen Knowle

GCDAMP Technical W

June 24, 201
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Overview• Alternatives• Modeling and SDM

• Emerging Hybrid Alternative• Experimental Design

• Schedule

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Alternatives Being Analyzed in EIS1. No‐Action Alternative (NA)2. Balanced Resource Alternative (BR)

3. Condition‐Dependent Adaptive Strategy (CDA)

4. Resource Targeted Condition‐Dependent Alternative 5. Seasonally Adjusted Steady Flows (SASF)

6. Year‐Round Steady Flows (YRSF)

• Note that BR, CDA & RTCD were modeled with several 

versions with various options turned on or off.
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Completion of Modeling and Structured Decision • The majority of the modeling for the LTEMP Draft EIS 

completed, but interpretation, quality checking and p

continues as well as other qualitative and quantitative 

• Structured decision making process has been comple

has provided input both to stakeholder views and to th

information for experimental design.

• A decision regarding a preferred alternative has not a

not be made based solely on the structured decision or the modeling results, but will also use the informatgathered in the context of many other important sour

information such as public comments, additional mod

results, empirical data review, qualitative analysis, and policy analysis.
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Multi‐criteria Decision Analysis

StakeholderFederal State Tribe 

JL USFWS AZDWR AZGFD SRP UAMPS CREDA Hopi Hualapai Navajo 

No Action 0.474 0.506 0.493 0.444 0.504 0.491 0.508 0.516 0.521 0.490 

Balanced Resource BR1 0.485 0.503 0.522 0.448 0.526 0.529 0.523 0.514 0.532 0.509 

BR2 0.460 0.441 0.470 0.408 0.536 0.550 0.542 0.470 0.482 0.470 

CDAS 1 0.599 0.537 0.487 0.500 0.480 0.444 0.452 0.565 0.582 0.524 

2 0.590 0.514 0.473 0.512 0.456 0.418 0.441 0.566 0.577 0.521 3 0.390 0.437 0.406 0.375 0.474 0.466 0.481 0.429 0.416 0.401 4 0.552 0.507 0.467 0.492 0.487 0.453 0.474 0.534 0.533 0.505 

RTCD 1 0.584 0.532 0.536 0.501 0.519 0.505 0.495 0.574 0.595 0.550 

2 0.577 0.537 0.545 0.510 0.498 0.479 0.476 0.581 0.605 0.557 3 0.414 0.489 0.509 0.416 0.507 0.513 0.504 0.481 0.488 0.474 4 0.557 0.541 0.549 0.506 0.517 0.499 0.497 0.568 0.587 0.556 5 0.412 0.483 0.499 0.411 0.489 0.494 0.485 0.476 0.485 0.465 6 0.424 0.499 0.518 0.420 0.515 0.526 0.506 0.485 0.495 0.477 

SASF 0.560 0.467 0.403 0.486 0.329 0.291 0.318 0.514 0.525 0.439 

YRSF 0.565 0.539 0.449 0.506 0.434 0.370 0.395 0.528 0.547 0.498 

Best performing alternative for this stakeholder's weightingsAlternative performs better than No ActionAlternative performs worse than No ActionWorst performing alternative for this stakeholder's weightings
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Desired Characteristics of a Hybrid Alternati• Performs well relative to all resource goals and objecti• Meets humpback chub recovery goals

• Increase and retain sediment• Maintain or increase the hydropower resource

• Performs well on recreation metrics• Performs well on other resource metrics (cultural, veg

etc.)

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Characteristics of an Emerging Hybrid Altern

Component NotesMonthly volumes RTCDDaily fluctuations 10x/9x with 8k cap 10x fluctuations Jun‐Aug, 9x fluctuati

of year. Maximum daily range of 8,000 

Proactive spring HFEs Yes Test (only in >10 maf year)

Spring HFEs Yes Limit to 45 K for 96 hr

Fall HFEs Yes More flexibility in duration, up to 336 

Rapid response HFE NoTrout management flows Yes Test and continue if performs well

Low summer flows Yes

Test in second 10 years if needed, adj

14 or 15 C for Jul, Aug, Sep (only in ye

temp is achievable based on release t

Mechanical removal of

trout

Yes Condition dependent

Load curtailment Yes before,

test after

Load curtailment post‐HFE would occ

month of HFE only

Vegetation control Yes Adaptive vegetation restoration activi

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Review of Sediment Results

Preliminary Results—Do Not Cite or Distribute

• Hydrology is biggest driver, as for all resources• Frequency of HFEs and fluctuation levels are also importan• Low summer flows move water to April which causes great

sediment transport in the spring.

– Low summer flows do transport less sediment in the summer but 

completely compensate for the sediment lost in Spring.

– CDAS1 (w/o LSF) retains approximately 100 ktons more than CDAS

end of water year

– Approximately the same difference in sediment transport betwee

RTCD2

• TMFs have little to no impact on SLI. There is little effect on 

especially by end of year

• Load curtailment has increased SMBI by 9 kton (annual diff

RTCD)

Preliminary Results—Do Not Cite or Distribute 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Screening Tool Estimates of Sediment Transport to SepFluctuation and Monthly Volume Effects

Preliminary Results—Do Not Cite or Distribute

Annual Sediment

Transport (MT)

Annual Sedi

Transport (%

Monthly

Pattern

Fluctuation

Level

(high/low

demand) 8.23 maf 12 maf 8.23 maf 

CDAS 7/7 321,111 1,944,581 89.6% 

RTCD 7/7 271,883 1,794,444 75.9% RTCD 10/9/8k cap 324,063 1,807,467 90.4% RTCD 12/10 361,083 2,065,655 100.8% 

MLFF 5K, 6K, 8K 358,266 1,858,317 100.0% 

Preliminary Results—Do Not Cite or Distribute 

Lower sediment transport than original CDAS and RTCD
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Review of Hydropower Results• Differences can be tied to frequency of HFEs and fluct

levels

• Value of Generation: RTCD1 produces $4M/year more 

value than CDAS1

• Value of Capacity: RTCD1 has $4.9M/year more capaci

than CDAS1

• Both RTCD and CDAS include 2,500 cfs down ramp rate 

an improvement relative to No Action (was 1500 cfs in 

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Screening Tool Estimates of Hydropower Value to Sepa

Fluctuation and Monthly Volume Effects

Preliminary Results—Do Not Cite or Distribute

Annual Hydropower

Value ($M)

Annual Hydropo

(%MLFF

Monthly

Pattern

Fluctuation

Level

(high/low

demand) 8.23 maf 12 maf 8.23 maf 

CDAS 7/7 210 305 97.0% 

RTCD 7/7 210 305 97.2% RTCD 10/9/8k cap 214 306 99.1% RTCD 12/10 216 310 99.8% 

MLFF 5K, 6K, 8K 216 307 100.0% 

Preliminary Results—Do Not Cite or Distribute 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Review of HBC Results

Preliminary Results—Do Not Cite or Distribute

• Biggest factors affecting the number of chubs in altern

were steady flows, TMFs or frequency of HFEs

• Hydrology (wet vs. dry) makes more difference to trou

production than does the differences between most a

• Hybrid alternative should perform better for HBC than 

comparable to CDAS1 and RTCD1. Performs better tha

YRSF for HBC

Preliminary Results—Do Not Cite or Distribute 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Lowest Adult HBC pop. (x1,000)

NA BR1 BR2CDAS1CDAS2CDAS3CDAS4RTCD1RTCD2RTCD3RTCD4RTCD5RTCD6

05

1015

Minimum Adult HBC population size (x1000)

LSF LSF LSF 

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Fluctuation levels• 10x/9x/8k cap explanation• 10 = a 10x factor of monthly volume (in kaf) to get ma

daily change (in cfs)

In a 700 kaf month, maximum daily change = 7000 cfs

This factor applies to June, July and August.

• 9 = a 9x factor for the other 9 months of the year• 8k cap = a maximum daily change of 8000 cfs, which is 

as current MLFF constraint.
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Comparison of RTCD 10/9 8k cap with MLFF

8.23 maf year

RTCD with 10/9 with 8k max MLFF

MonthlyVolume (kaf)

Mean dailyflow Daily Change

MonthlyVolume (kaf)

Mean daily

flow Daily Change

October 643 10451 5783 600 9758 6000 November 642 10781 5774 600 10083 6000 December 716 11643 6443 800 13011 6000 January 781 12707 7032 800 13011 6000 February 691 12449 6222 600 10804 6000 March 730 11870 6569 600 9758 6000 April 650 10922 5849 600 10083 6000 May 672 10935 6052 600 9758 6000 June 704 11829 7039 650 10924 6000 July 767 12471 7668 850 13824 8000 August 659 10721 6592 900 14637 8000 September 575 9668 5177 630 10588 6000 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Comparison of RTCD 10/9 8k cap with MLFF

12 maf year

RTCD with 10/9 with 8k max MLFF

MonthlyVolume (kaf)

Mean daily

flow Daily Change

MonthlyVolume (kaf)

Mean dailyflow Daily Change

October 643 10451 5783 600 9758 6000 November 642 10781 5774 600 10083 6000 December 716 11643 6443 800 13011 6000 January 1282 20858 8000 1000 16263 8000 February 1135 20435 8000 800 14405 6000 March 1198 19484 8000 900 14637 8000 April 1067 17929 8000 1000 16806 8000 May 1104 17950 8000 1100 17890 8000 June 1155 19417 8000 1200 20167 8000 July 1259 20471 8000 1400 22769 8000 August 961 15632 8000 1500 24395 8000 September 839 14097 7549 1100 18486 8000 
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Benefits of Hybrid Alternative Relative to Original AlterConsidered• Blends multiple alternatives that were weighted highly by a 

variety of stakeholders in structured decision analysis proce

• Uses the monthly volume pattern of RTCD that more closel

power demand to improve hydropower performance and sconservation

• Represents an improvement over CDAS and RTCD in terms 

sediment transport and conservation

• Preserves beneficial effects of TMFs on humpback chub nu

• Tests a variety of condition‐dependent elements to improv

and humpback chub conservation

• Maintaining an 8000 cfs fluctuation cap has benefits for sed

recreation

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Elements of an Experimental Design• For all experiments, identify:

– Hypotheses being tested

– Design of monitoring component

– Adaptive response to information generated by experiment th

and easy to adapt to new information

– Implementation of multiple tests and avoidance of confoundin

the extent practicable

– Focus is on management tools as a suite as opposed to a focus 

separating out effects of individual treatments

– Continued monitoring for unintended/unexpected results and 

off‐ramps as needed

Preliminary Results—Do Not Cite or Distribute
Glen Canyon Dam

Long‐Term Experimental and Management Plan EIS

Timeline• Post Modeling Discussions

– Hybrid Alternative Components

– Experimental Design– Peer Review

• Preliminary Draft #1 to cooperators and tribes – end of July

– No preferred alternative

– Tribes to provide input, others use as informational

• Preliminary Draft #2 to cooperators, tribes and GCMRC – end of 

– Plan to have a preferred alternative

– Will include tribal input

• Public Draft – end of October

– Will include full hydropower and ratepayer analysis