Technical Working Group

Glen Canyon Operations

Basin Hydrology and Water Quality

January 26, 2023

1
Upper Basin Storage (as of January 25, 2023)

Percent Current Live 

Current Live Storage Elevation Reservoir Live Storage Capacity (feet)

Storage (maf) (maf)

Fontenelle 52 0.17 0.33 6,482.52

Flaming 68 2.50 3.67 6,007.47 Gorge

Blue Mesa 36 0.29 0.83 7,447.25

Navajo 52 0.85 1.65 6,018.09

Lake Powell 24 5.48 23.31 3,523.91

UC System 31 9.43 29.79 Storage

Total System 33 19.10 58.48 Storage

2
January Month and WY Precipitation

3

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

Precipitation Forecast

4
Upper Colorado SWE and Observed Inflows

5

Available online at: https://waterwatch.usgs.gov/index.php?id=wwdur_cumrunoff
6 https://www.nrcs.usda.gov/Internet/WCIS/AWS_PLOTS/basinCharts/Proj/WTEQ/stdHUC2/14_Upper_Colorado_Region.html
 

 

 

Most Probable January Forecast

Water Year 2023 

April – July 2023 Water Year 2023 

Forecasted Unregulated Inflow Unregulated Inflow Forecast 

as of January 5, 2023 as of January 5, 2023 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 700 95 

Flaming Gorge 950 98 

Blue Mesa 605 95 

Navajo 570 91 

Powell 6,700 105 

Powell midmonth = 7,500 maf (117%) 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 990 92 

Flaming Gorge 1,323 94 

Blue Mesa 838 93 

Navajo 790 87 

Powell 9,498 99 

Powell midmonth = 10,418 maf (109%) 

1

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

7 
8

January 2023 WY MidMonth

April-July 7.50 maf (117%)

Most Prob: 10.42 maf (109%)
Upper Colorado Basin

Hydrology and Operations

Projections Based on January 

2023 24-Month Study

9
Upper Basin Drought Response Actions

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• The Bureau of Reclamation announced on May 3, 2022, two separate urgent drought response 

actions that will help prop up Lake Powell by nearly 1 million acre-feet (maf) of water over the next 

12 months (May 2022 through April 2023). To protect Lake Powell, more water will flow into the lake 

from upstream reservoirs and less water will be released downstream:

• Under a Drought Contingency Plan adopted in 2022, approximately 500 thousand acre-feet (kaf) of water 

will come from Flaming Gorge Reservoir, located approximately 455 river miles upstream of Lake Powell 

(2022 Plan). 

• For more information: https://www.usbr.gov/uc/DocLibrary/Plans/20220429-2022DroughtResponseOperationsPlan-ApprovalMemo508-DOI.pdf. 

• Another 480 kaf will be left in Lake Powell by reducing Glen Canyon Dam’s annual release volume from 

7.48 maf to 7.00 maf (GC Operational Adjustment), in accordance with Sections 6 and 7.D of the 2007 

Interim Guidelines.

• For more information: https://www.usbr.gov/uc/DocLibrary/Plans/20220503-2022DROA-GlenCanyonDamOperationsDecisionLetter508-DOI.pdf

• Glen Canyon Dam will hold back a total of 523 kaf during the months of December 2022 through April 

2023. There are continued discussions when and how that water will be released later in the year. 
Historical Future

Flaming Gorge 2022 Plan Daily Releases

Flaming Gorge DROA release as of January 22 = 393 kaf

Drought Response Operations Agreement (DROA)

11

Reservoir

2021 

DROA 

Volume

(kaf)

2022 

DROA 

Volume

(kaf)

Total 

DROA 

Volume 

(kaf)

Flaming Gorge 125 500 625

Blue Mesa 36 0 36

Navajo 0 0 0

Volume in 

Powell 161 500 661

DROA Volumes Released1

1DROA operational year is from May through April. 
• 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.

Upper Basin Reservoir Operations 

in Water Year 2023

12
13 
14 
Colorado River Mid-term Modeling System (CRMMS)

24-Month Study Mode CRSS

(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)

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

1 - 2 1 - 5 1 - 50

15

Reclamation Operational Modeling

Model Comparison
16

Most Probable End of CY 2022 Projection: 3,524.59 

feet (24% full)

Min/Max Range: 3,516.91 to 3,524.60 feet

Most Probable End of CY 2023 Projection: 

3,527.00 feet (24% full)

Min/Max Range: 3,481.67 to 3,589.18 feet
Lake Mead End of Month Elevations1

Projections from the January 2023 24-Month Study Inflow Scenarios

17

Most Probable End of CY 2023 Projection: 

1,026.91 feet (23% full)

Min/Max Range: 1,017.45 to 1,057.23 feet

Most Probable End of CY 2024 Projection: 

1,017.57 feet (21% full)

Min/Max Range: 996.16 to 1,047.62 feet

The chart above displays projected “physical” elevations for Lake Mead.
Upper Colorado Basin

Hydropower 

Maintenance

18
Glen Canyon Dam Power Plant Unit Outage Schedule for 2023

19
Glen Canyon Dam Power Plant Unit Outage Schedule for WY2024

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24 
Water Quality

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10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230

Lake Powell Temperature Dec 2022

3200

3250

3300

3350

3400

3450

3500

1

3

5

7

9

11

13

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19

21

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Deg C

elevation, ft

Km from Dam

Penstock

River Outlet
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4

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10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230

Lake Powell December 2022 Dissolved Oxygen

3200

3250

3300

3350

3400

3450

3500

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2

3

4

5

6

7

8

9

10

11

12

13

14

mg/L

elevation, ft

Penstock

Km from Dam

River Outlet


Penstock


Questions?

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