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Glen Canyon Dam Technical Work Group 

Agenda Item Information 

June 24-25, 2014

Agenda Item 

Basin Hydrology, Operations and 2015 Hydrograph 

Action Requested 

 Propose a motion for AMWG 

Presenter 

Katrina Grantz, Hydraulic Engineer, Bureau of Reclamation, Upper Colorado Region 

Previous Action Taken 

 By AMWG: At the August 2013 meeting, the AMWG passed a motion to recommend to the 

Secretary of the Interior her approval of the DOI-DOE Proposed Hydrograph for Water Year 

2014. Previous year hydrographs (water years 2012 and 2013) were also reviewed by the TWG, 

and the AMWG and approved by the Secretary of the Interior. 

Relevant Science 

The TWG and AMWG have been presented with sediment and financial results from the DOIDOE analysis of operational scenarios for the 2012, 2013, and 2014 Hydrographs. These analyses 

were based upon the USGS sand retention model and Western’s GTMax power/financial model. In 

May 2014, the AMWG was presented with a range of possible operational scenarios for a potential 

water year 2015 hydrograph. The anticipated range of conditions and objectives for 2015 remain 

similar to the previous years; therefore, the targeted approach adopted as the 2012, 2013 and 2014 

Hydrographs is recommended again for the 2015 Hydrograph. 

Background Information 

The first portion of the presentation is intended to provide pertinent information to TWG members 

on current water supply and forecasted hydrologic conditions within the Upper Colorado River 

Basin. The presentation will focus on projected reservoir conditions and operations at Lake 

Powell/Glen Canyon Dam for the remainder of water year 2014 and provide an outlook for 2015. 

The second portion of the presentation will cover the potential range of annual release volumes 

from Lake Powell in water year 2015 and the proposed 2015 Hydrograph. 
Basin Hydrology, Operations 

2015 Hydrograph

Glen Canyon Dam Technical Work G

June 25, 2014

Katrina A

Hydraulic Enginee

Bureau of 
• Upper Colorado River Bas

Hydrology

• Glen Canyon Dam Operati

(WY 2014 and 2015) 

2
3

Upper Basin 

Snowpack 

on April 1, 2014

http://www.usbr.gov/uc/water/notice/Graphs/Upper_C

Upper Colorado Basin Hydrolog
Past 30 days of inflow and pool ele
5

June Mid-month: 7.25 (101%)
WY2014 Operations under Interim Guid

determined in August 2013 24-Month Study

Scenario Operational Tier Annual Release Volume

Minimum

Probable

Mid-Elevation 

Release 7.48 maf

Most

Probable

Mid-Elevation 

Release 7.48 maf

Maximum 

Probable

Mid-Elevation 

Release 7.48 maf

* Note that in the Mid-Elevation Release Tier, there is no provision for an April adjustment to the operating tier. 

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7
8

Water Year 2015 Operating Tier 

will be determined in August 2014
9

Water Year 20

Most: 9.0 

Max: 11.4 

Min: 9.0 m
Unit 

Number

Oct 

2013

Nov 

2013

Dec 

2013

Jan 

2014

Feb 

2014

Mar 

2014

Apr 

2014

May 

2014

Jun 

2014

Jul 

2014

12345678

Units 

Available 5 66 6 66

Capacity 

(cfs) 14,200 18,000 17,900 16,600 17,000 17,00

Capacity 

(kaf/month) 900 1040 1120 1100 750 850 950 950 1010 1050 

Max (kaf) 1 -- -- -- -- -- -- -- -- 600 800 

Most (kaf) 2 481 696 601 800 600 504 502 493 600 800 

Min (kaf) 1 -- -- -- -- -- -- -- -- 600 800 

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Glen Canyon Power Plant Provisional Unit Outage Schedule for Wate

(up

6

13,800

17,000

5

6

10,300

16,600

4

5

20,000

14,300

6

4

13,600

10,300

5

1 Projected release, based on April 2014 Min and Max Probable 

Inflow Projections and 24-Month Study model runs

2 Projected release, based on June 2014 Most Probable Inflow 

Projections and 24-Month Study model runs
Unit 

Number

Oct 

2014

Nov 

2014

Dec 

2014

Jan 

2015

Feb 

2015

Mar 

2015

Apr 

2015

May 

2015

Jun 

2015

Jul 

2015

12345678

Units 

Available 5766 4 6 66

Capacity 

(cfs) 13,800 20,600 17,200 17,200 10,700 17,200 17,200 17,20

Capacity 

(kaf/month) 870 1180 1060 1060 630 880 1020 930 1020 1060 

Max (kaf) 1 600 600 800 950 700 800 1000 1200 1200 1250 

Most (kaf) 2 600 600 800 800 650 650 600 650 800 1000 

Min (kaf) 1 600 600 800 800 650 650 600 650 800 1000 

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Glen Canyon Power Plant Provisional Unit Outage Schedule for Wate

1 Projected release, based on April 2014 Min and Max Probable 

Inflow Projections and 24-Month Study model runs

2 Projected release, based on June 2014 Most Probable Inflow 

Projections and 24-Month Study model runs

6

10,400

17,200

4

5

17,200

13,600

6

(up
DOI-DOE Hydrograph

Development 

for Water Year 2015

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2015 Hydrograph Developm

• Start 2012, 2013, and 2014 hydrograph

– “Targeted Approach” 

• Consider operating experiences and inpu• Continue to work within existing environm

compliance 

13
2015 Hydrograph Concep

• Objective: retain sand inputs high in the system 

anticipation of a potential HFE in fall 2015

• Target lower August through October releases• Avoid shifting “extra” water to June (which cools 

temperatures at the mouth of the LCR)

• Move water from August to other equal value mo

hydropower (Dec/Jan, Jul)

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Dave Trueman

dtrueman@usbr.gov

(801) 524-3759

Manager

Resource Management Division

Upper Colorado Region

Salt Lake City, UT

Objective: better preserve August 

and September sand inputs for 

potential HFE in November. 

Typical 

greatest 

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Typical months of higher 

release volumes:

July and August

(also Dec, Jan)
Decreasing releases in the 

1,000kaf to 800kaf range can 

significantly decrease sand 

transport. Less difference seen at 

lower flow volumes.

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Temperature Considerations

• Last year (2013) FWS suggested we look at way

improve temperatures at the mouth of the LCR eseason (June)

• LCR temperatures were found to drop by about 

as releases are increased from 600 to 800 kaf

• Avoid shifting “extra” water into June• June release target will be:

– 600 to 650 kaf for annual releases below 9.0 maf– 800 kaf for annual releases of 9.0 maf to less than 9.5 maf– 900 kaf for annual releases of 9.5 maf to less than 10 maf– Greater than 900 kaf for annual releases 10 maf and greate

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2015 Targeted Release Volum

• August releases targeting 800kaf, and adjusted to accoun

hydrologic uncertainty. 

– If there is a HFE in November 2014, August 2015 releases that wer

above 800 kaf may be reallocated to November

• September releases adjusted to the forecast as follows:

– 600 kaf/month for annual releases below 9.0 maf– 700 kaf/month for annual release from 9.0 maf up to 10.0 maf– 800 kaf/month for annual release from 10.0 maf up to 11.0 maf– 900 kaf/month for annual release from11.0 maf up to 12.0 maf– Up to powerplant capacity for high equalization releases

NOTE: Propose similar release targets and language as 2013 hydrograph (was in Upper Elevation Balancing Tier), also accounting for powerplant capaconstraints.

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2015 Projected Annual Rele

(Based on April and June 2014 modeling

)

• Minimum probable: 9.0 maf release 

Upper Elevation Balancing, with 9.0 release; extremely small chance of 8.23 or 7.4

• Most probable: 9.0 maf release 

Upper Elevation Balancing, with 9.0 release

• Maximum probable: ~11 maf release 

Upper Elevation Balancing, with April adjustment to equalization

• GCD Operating Tier will be determined in August• If Upper Elevation Balancing Tier, potential for April adjus

equalization. 

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2015 Possible Hydrograp

7.48 maf release

• Flows are already low – no difference from typical ML

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2015 Possible Hydrograp

8.23 maf release

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2015 Possible Hydrograp

9.0 maf release

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2015 Possible Hydrograp

11 maf release

• Lots of water to move: limited flexibility, powerplant capac

anticipated, minimal ability to affect sand retention or temp

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2015 Hydrograph Next Ste

• Continue to coordinate with DOI-DOE Ag• No additional modeling for 2015

– We have already analyzed the range of annu

release volumes in past years:

• Projected hydropower impacts: GTMax• Projected sediment retention: Sand Budget model• Projected temperature impacts

• If acceptable to TWG, TWG will move to 

for recommendation to Secretary at AuguAMWG meeting.

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Questions?

Katrina Grantz

801-524-3635

kgrantz@usbr.gov

Hydraulic Engineer, Glen Canyon

Reclamation, Upper Colorado Region

Resource Management Division

Water Resources Group

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2015 Proposed Language

• Annual Release Volumes will be determined by the 2007 Interim Guidelines and shall be reviewed and adopted thr

annual operating plan process. 

•• Monthly Release Volumes will be adjusted each month based on the most current inflow forecast, the projected An

Volume, powerplant capacity, and the magnitude of a potential High Flow Experiment.

•• Release objective for June is to avoid reallocating releases from August into June and is intended to provide warm

at the mouth of the Lower Colorado River early in the season for endangered fish. The 2015 June release target vadjusted with the projected annual release volume to: 600 to 650 kaf for annual releases below 9.0 maf800 kaf for annual releases of 9.0 maf to less than 9.5 maf900 kaf for annual releases of 9.5 maf to less than 10 mafGreater than 900 kaf for annual releases 10 maf and greater

•• Release objective for August of 800 kaf is intended to reduce the erosion of August sediment inputs in anticipation 

However, due to hydrologic uncertainty and powerplant capacity constraints in other months, the August 2015 relea

may be adjusted. Should a HFE be conducted in November 2014, August 2015 releases scheduled above 800 ka

to November. 

•• Release objective for September is intended to reduce the erosion of August sediment inputs in anticipation of a po

2015 September release target volume will be adjusted with the projected annual release volume to: 

• 600 kaf for annual releases below 9.0 maf • 700 kaf for annual releases of 9.0 maf to less than 10.0 maf • 800 kaf or greater for annual releases of greater than 10.0 maf; up to powerplant capacity for high equalization rele

•• Monthly Release Volumes will generally strive to maintain 600 kaf levels in the shoulder months (spring and fall) an

December/January and July/August timeframes to meet Western’s minimum power needs. 

•• Additionally, the Bureau of Reclamation will continue to apply best professional judgment in conducting actual oper

response to changing conditions throughout the water year. Such efforts will continue to be undertaken in coordina

DOI/DOE agencies to consider changing conditions and adjust projected operations in a manner consistent with thparameters as stated above and pursuant to the Law of the River. 
2012 

Hydrograph Language
FY 2013 Hydrograph

Reclamation proposes to use a similar design to FY 2012 Hydrogra

developed by DOI Team and recommended by AMWG, the “TarMethod”:

• August releases are limited using percentage method to conserv

inputs with an emphasis on the primary sediment input period of October.

• Only September and October would differ from the 2012 Hydrog

because they will not be steady, but will revert to ROD fluctuatio

• September and October releases would be adjusted to the forec

follows:

– 600 kaf/month for annual releases below 9.0 maf– 700 kaf/month for annual release from 9.0 maf up to 10.0 m– 800 kaf/month for annual release from 10.0 maf up to 11.0 m– 900 kaf/month for annual release from11.0 maf up to 12.0 m– Up to powerplant capacity for high equalization releases
2014 Hydrograph langua

• Annual Release Volumes will be determined in compliance with the 2007 Interim 

consultation with the Basin States as appropriate).

• Monthly release Volumes are anticipated to shift depending upon: (1) the Annua

and (2) the magnitude of a potential High Flow Experiment.

• Monthly Release Volumes may vary within the targets identified below. Any rem

operational flexibility will be used for existing power production operations undeFluctuating Flow (MLFF) alternative selected by the 1996 ROD and contained in t

compliance with all applicable NEPA compliance documents (HFE EA, NNFC EA

• 2007 IG).• Release objective for June is 600 kaf to 650 kaf .

• Release objective for August is 800 kaf.• Release objective for September and October is 600 kaf to 630 kaf (or less).• Monthly Release Volumes will generally strive to maintain 600 kaf levels in the s

and 800 kaf in December/January and July/August timeframe.

• Additionally, the Bureau of Reclamation will continue to apply best professional 

conducting actual operations and in response to changing conditions througho

Such efforts will continue to be undertaken in coordination with the DOI/DOE agconsultation with the Basin States as appropriate, to consider changing conditioprojected operations in a manner consistent with the objectives of these parameabove and pursuant to the Law of the River.

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