Glen Canyon AMWG

Basin Hydrology and Operations

August 16, 2023

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Upper Colorado Basin System Conditions (as of August 10, 2023)

Reservoir

Percent 

Current 

Live 

Storage

Current 

Live 

Storage

(maf)

Live 

Storage 

Capacity 

(maf)

Elevation

(feet)

Fontenelle 95 0.32 0.33 6,503.90

Flaming 

Gorge 90 3.32 3.67 6,031.29

Blue Mesa 88 0.73 0.83 7,508.15

Navajo 75 1.24 1.65 6,055.39

Lake Powell 39 9.15 23.31 3,578.23

UC System 

Storage 50 14.87 29.93

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Upper Colorado SWE and Observed Inflows

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https://waterwatch.usgs.gov/index.php
 

Drought Response Operations Agreement (DROA) 

Completed DROA Volumes1,2 

Reservoir 

2021 

DROA 

Volume 

(kaf) 

2022 

DROA 

Volume 

(kaf) 

2023 

DROA 

Volume 

(kaf)4 

Total 

DROA 

Volume 

(kaf) 

Flaming 

Gorge 125 3283 -193 260 

Blue Mesa 36 0 0 36 

Navajo 0 0 0 0 

Total DROA 

Volume 

(kaf) 

161 328 -193 296 

1

DROA operational year is from May through April. 

2Positive values indicate Drought Response Operations Releases and negative 

values indicate Drought Response Operations Recovery 3 463 kaf of DROA releases prior to DROA release suspension on March 6, 2023. 

-135 kaf of DROA recovery from March 7, 2023 through April 30, 2023 

4 4DROA recovery through June 2023 
Most Probable August Preliminary Observed and 

Forecast Water Year 2023 

April – July 2023

Preliminary Observed 

Unregulated Inflow 

as of August 1, 2023 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 951 129 

Flaming Gorge 1,457 151 

Blue Mesa 833 131 

Navajo 1,028 163 

Powell 10,619 166 

Water Year 2023 

Unregulated Inflow Forecast 

as of August 1, 2023 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 1,251 116 

Flaming Gorge 1,810 128 

Blue Mesa 1,083 120 

Navajo 1,265 139 

Powell 13,750 143 

1

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

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Most Probable August Forecast

Water Year 2024 

April – July 2024 

Forecasted Unregulated Inflow 

as of August 1, 2023 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 690 94 

Flaming Gorge 920 95 

Blue Mesa 620 97 

Navajo 577 92 

Powell 6,420 100 

Water Year 2024 

Unregulated Inflow Forecast 

as of August 1, 2023 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 1,030 96 

Flaming Gorge 1,380 98 

Blue Mesa 895 99 

Navajo 845 93 

Powell 10,000 104 

1

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

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Upper Colorado Basin 

Hydrology and Operations 

Projections Based on August 

2023 24-Month Study 

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Upper Basin Reservoir Operations 

Water Years 2023 and 2024

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• 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 water year (WY) 2023 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

• Lake Powell WY 2024 will operate in the Mid-Elevation Release Tier where Lake Powell will release 

7.48 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 nongovernmental organizations with respect to implementation of these monthly and annual operations.
Lake Powell & Lake Mead Operational Table

Lake Powell Operational Tier Determination Run (aka “Exhibit Run”) with an 8.23 maf Release1

3,568.57 ft

Jan 1, 2024 

Projection

1 10 Lake Powell and Lake Mead operational tier determinations will be documented in the draft 2024 AOP.
 

 

 

 

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. 

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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 

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Reclamation Operational Modeling

Model Comparison 
Most Probable End of CY 2023 Projection:

3,573.68 feet (38% full)

Min/Max Range: 3,568.78 to 3,583.38 feet

Most Probable End of CY 2024 Projection:

3,589.09 feet (43% full)

Min/Max Range: 3,550.94 to 3,656.00 feet

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Most Probable End of CY 2023 Projection:

1,065.27 feet (34% full)

Min/Max Range: 1,064.74 to 1,066.20 feet

Most Probable End of CY 2024 Projection:

1,057.43 feet (32% full)

Min/Max Range: 1,048.13 to 1,060.93 feet

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Glen Canyon Dam Power Plant Unit Outage Schedule for 2024

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Questions?

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