Glen Canyon Monthly

Operations Call 

Basin Hydrology and Operations 

April 12, 2023 
 

 

 

 

 

 

 

 

 

 

Background 

This briefing is being provided consistent with the 

provision in Attachment B - Section 1.1 of the LTEMP ROD 

which states: 

“Annually, Reclamation will develop a hydrograph based on the characteristics 

above. Reclamation will seek consensus on the annual hydrograph through 

monthly operational coordination calls with governmental entities, and regular 

meetings of the GCDAMP Technical Working Group (TWG) and AMWG. 

Reclamation will conduct monthly Glen Canyon Dam operational coordination 

meetings or calls with the DOI bureaus (USGS, NPS, FWS, and BIA), WAPA, and 

representatives from the Basin States and UCRC. The purpose of these meetings or 

calls is for the participants to share and seek information on Glen Canyon Dam 

operations. One liaison from each Basin State and from the UCRC may participate 

in the monthly operational coordination meetings or calls.” 

2 
Upper Basin Storage (as of April 10, 2023) 

3 

Reservoir 

Percent 

Current 

Live 

Storage 

Current 

Live 

Storage 

(maf) 

Live 

Storage 

Capacity 

(maf) 

Elevation 

(feet) 

Fontenelle 31 0.10 0.33 6,468.04 

Flaming 

Gorge 68 2.48 3.67 6,006.77 

Blue Mesa 37 0.30 0.83 7,448.48 

Navajo 58 0.96 1.65 6,029.83 

Lake Powell 23 5.27 23.31 3,520.18 

UC System 

Storage 31 9.25 29.79 

Total System 

Storage 32 18.97 58.48 
April Month and March WY Precipitation 

4 

Month to Date Precipitation WY Precipitation 
Climate Prediction Center Short-Term 

Precipitation Forecast 

5 
Upper Colorado SWE and Observed Inflows 

Available online at: https://waterwatch.usgs.gov/index.php?id=wwdur_cumrunoff 

6 
Glen Canyon Raw ESP Forecast Trends 

7 
 

 

Most Probable April Forecast 

Water Year 2023 

April – July 2023 Water Year 2023 

Forecasted Unregulated Inflow Unregulated Inflow Forecast 

as of April 5, 2023 as of April 5, 2023 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 800 109 

Flaming Gorge 1,200 124 

Blue Mesa 850 134 

Navajo 945 150 

Powell 11,300 177 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 1,095 102 

Flaming Gorge 1,548 110 

Blue Mesa 1,101 122 

Navajo 1,195 131 

Powell 14,472 151 

1

Averages are based on the 1991 through 2020 period of record. 

8 
9 
 

Upper Colorado Basin 

Hydrology and Operations 

Projections Based on January 

and March 2023 24-Month 

Study 

10 
 

 

 

 

 

Drought Response Operations Agreement (DROA) 

Flaming Gorge 2022 Plan Daily Releases 

DROA Volumes Released1 

Reservoir 

2021 

DROA 

Volume 

(kaf) 

2022 

DROA 

Volume 

(kaf) 

Total 

DROA 

Volume 

(kaf) 

Flaming Gorge 125 463 588 

Blue Mesa 36 0 36 

Navajo 0 0 0 

Volume in 

Powell 161 463 624 

1DROA operational year is from May through April. 

Flaming Gorge DROA final volume = 463 kaf 

11 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Upper Basin Reservoir Operations 

in Water Year 2023 

• Lake Powell will be operated consistent with the 2007 Interim Guidelines, the Upper Basin Drought Response 

Operations Agreement and Upper Basin Records of Decision 

• Lake Powell’s projected end of calendar year (CY) 2022 “tier determination” elevation in the August 2022 24-Month 

Study determines Lake Powell’s operating tier in CY 2023 

• Lake Powell will operate in the Lower Elevation Balancing Tier where Lake Powell and Lake Mead will balance contents with Glen Canyon 

Dam release volumes no less than 7.0 maf and no more than 9.5 maf 

• Consistent with the provisions of the 2007 Interim Guidelines, and to preserve the benefits to Glen Canyon Dam 

facilities from 2022 Operations into 2023 and 2024, Reclamation will consult with the Basin States on monthly and 

annual operations. Reclamation will also ensure all appropriate consultation with Basin Tribes, the Republic of 

Mexico, other federal agencies, water users and non-governmental organizations with respect to implementation of 

these monthly and annual operations. 

• The Glen Canyon Dam annual release has initially been set to 7.00 maf, and in April 2023 Reclamation will evaluate hydrologic conditions 

to determine if balancing releases may be appropriate under the conditions established in the 2007 Interim Guidelines; 

• Balancing releases will be limited (with a minimum of 7.00 maf) to protect Lake Powell from declining below elevation 3,525 feet at the 

end of December 2023; 

• Balancing releases will take into account operational neutrality of the 0.480 maf that was retained in Lake Powell under the May 2022 

action1. Any Lake Powell balancing release volume will be calculated as if the 0.480 maf had been delivered to Lake Mead 

in WY 2022; and 

• The modeling approach for WY 2023 will apply to 2024. 12 
 

 

Most Probable March Forecast 

Water Year 2023 

April – July 2023 Water Year 2023 

Forecasted Unregulated Inflow Unregulated Inflow Forecast 

as of March 3, 2023 as of March 3, 2023 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 620 84 

Flaming Gorge 880 91 

Blue Mesa 665 105 

Navajo 735 117 

Powell 8,000 125 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 916 85 

Flaming Gorge 1,264 90 

Blue Mesa 904 100 

Navajo 953 105 

Powell 10,869 113 

1

Averages are based on the 1991 through 2020 period of record. 

13 
14 
 

 

 

WY2023 March 24MS Official All scenarios are for discussion purposes to assist Reclamation in the GCD decision-making process. 

WY2023 Oct-22 Nov-22 Dec-22 Jan-23 Feb-23 Mar-23 Apr-23 May-23 Jun-23 Jul-23 Aug-23 Sep-23 Total 

Max Powerplant Release (kaf) 480 498 550 501 480 485 1,030 1,100 1,090 1,140 1,130 770 

7.0 maf LTEMP Pattern (kaf) 480 500 600 664 587 620 552 550 577 652 696 522 7,000 

Mar23 24MS Official 7.83 maf Pattern (kaf) 480 498 550 501 480 485 552 770 905 925 966 713 7,825 

15 
 

 

 

 

WY2023 Potential GCD Release of 9.0 maf All scenarios are for discussion purposes to assist Reclamation in the GCD decision-making process. 

WY2023 Oct-22 Nov-22 Dec-22 Jan-23 Feb-23 Mar-23 Apr-23 May-23 Jun-23 Jul-23 Aug-23 Sep-23 Total 

Max Powerplant Release (kaf) 480 498 550 501 480 485 1,030 1,100 1,090 1,140 1,130 1,130 

7.0 maf LTEMP Pattern (kaf) 480 500 600 664 587 620 552 550 577 652 696 522 7,000 

Mar23 24MS Official 7.83 maf Pattern (kaf) 480 498 550 501 480 485 552 770 905 925 966 713 7,825 

Mar-23 9.0 maf Pattern (kaf) 480 498 550 501 480 485 700 750 905 1,000 1,030 757 8,136 

16 
 

 

 

 

 

WY2023 Potential GCD Release of 9.5 maf All scenarios are for discussion purposes to assist Reclamation in the GCD decision-making process. 

WY2023 Oct-22 Nov-22 Dec-22 Jan-23 Feb-23 Mar-23 Apr-23 May-23 Jun-23 Jul-23 Aug-23 Sep-23 Total 

Max Powerplant Release (kaf) 480 498 550 501 480 485 1,030 1,100 1,090 1,140 1,130 1,130 

7.0 maf LTEMP Pattern (kaf) 480 500 600 664 587 620 552 550 577 652 696 522 7,000 

Mar23 24MS Official 7.83 maf Pattern (kaf) 480 498 550 501 480 485 552 770 905 925 966 713 7,825 

Mar-23 9.0 maf Pattern (kaf) 480 498 550 501 480 485 700 750 905 1,000 1,030 757 8,136 

Mar-23 9.5 maf Pattern (kaf) 480 498 550 501 480 485 700 900 990 1,000 1,050 752 8,386 17 
18 

PROVISIONAL INFORMATION – HFE STILL UNDER DISCUSSION 
 

 

 

 

 

 

Reclamation Operational Modeling

Model Comparison 

Colorado River Mid-term Modeling System (CRMMS) 

24 CRSS -Month Study Mode 

(Manual Mode) 

Ensemble Mode 

(Rule-based Mode) 

Primary Use 

AOP tier determinations and 

projections of current 

conditions 

Risk-based operational planning 

and analysis 

Long-term planning, comparison of 

alternatives 

Simulated Reservoir 

Operations Operations input manually Rule-driven operations 

Probabilistic or 

Deterministic 

Deterministic – single 

hydrologic trace 

Deterministic OR 

Probabilistic 30 (or more) 

hydrologic traces 

Probabilistic – 100+ traces 

Time Horizon (years) 1 - 2 1 - 5 1 - 50 

Upper Basin Inflow Unregulated forecast, 1 trace Unregulated ESP forecast, 30 traces Natural flow; historical, paleo, or 

climate change hydrology 

Upper Basin Demands Implicit, in unregulated inflow forecast Explicit, 2016 UCRC assumptions 

Lower Basin Demands Official approved or operational Developed with LB users 

19 
 

 

Most Probable End of CY 2023 Projection: 

3,552.00 feet (31% full) 

Min/Max Range: 3,539.35 to 3,580.99 feet 

Most Probable End of CY 2024 Projection: 

3,567.21 feet (36% full) 

Min/Max Range: 3,521.91 to 3,614.35 feet 

20 
 

Most Probable End of CY 2023 Projection: 

1,033.42 feet (25% full) 

Min/Max Range: 1,020.55 to 1,057.23 feet 

Most Probable End of CY 2024 Projection: 

1,017.58 feet (21% full) 

Min/Max Range: 1002.48 to 1,047.62 feet 

21 
Water Quality 

22 
7.823 maf 

7.823maf 

Penstock 

7.823maf 

April 15, 2023 

Penstock 

9.0maf 

April 15, 2003 

Penstock 
Penstock 

April 15, 2023 

Penstock 

April 15, 2023 

Penstock 

River Outlet 
Lake Powell March 7, 2023 Temperature elevation, ft

3500

3450 Deg C

24

22

3400 20

18

16

14

3350

12

10

8

3300 6

4

2

0

3250

3200

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220

Km from GCD

Lake Powell March 7, 2023 Temperature elevation, ft 

3500 

3450 

PenstockPenstock 

Deg C 

24 

22 

3400 20 

18 

16 

14 

3350 

12 

10 

8 

3300 6 

4 

2 

0 

3250 

3200 

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 

Km from GCD 
Lake Powell March 7, 2023 Dissolved Oxygen elevation, ft 

3500 

3450 

3400 

3350 

3300 

3250 

3200 

4 

4 

8 

8 

8 

8 

Penstock 

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 

mg/L 

14 

13 

12 

11 

10 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

Km from GCD 
10 

10 

10 

10 

10 

10 

20 

10 

20 

20 

20 

10 

20 

10 

20 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

20 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

20

20

3650 

3600 

elevation, ft10

10

Penstock 

River Outlet 20

Lake Powell Forebay Temperature Jan 2000 - March 2023 

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 10 20 20 2020 20 20 20 20

3550 

Deg C 

3500 

22 

20 

18 

16 

14 

12 

10 

8 

6 

3450 

3400 

3350 

3300 

4 

2 

3250 

3200 

24 

0 
8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8 

8

8

4 

4

8 

8 

4 

4 

4 

4 

4 

8

8 

8 

8 

8 

8 

8 

4 

8 

8 

8 4 

8 

8 

8 

8 

8 

8 

8 

8 

4 

8 

8

8 4 

8 

8 

8 

4 

4 

8 

4

8 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4

4 

4 

4 

8 

4 

8 

8 

4 

4 

4 

4

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4

4 

4 

8 

8

8

elevation, ft 

3650 

3600 

DO mg/L 

3550 

3500 

3450 

3400 

3350 

3300 

8

4

4

4

8 8 4

8

8

4

4

2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

4

8

4

8 8

14 

13 

12 

11 

10 

9 

8 

7 

6 

5 

4 

3 

2 

Penstock 

4

River Outlet 

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 

4

Lake Powell Forebay Dissolved Oxygen Jan 2000 - March 2023

8

3250 

3200 

1 
Questions? 

35