GCDAMP Technical 

Management Work Group 

Basin Hydrology, Operations and

Water Quality 

November 7, 2023 

1 
Upper Basin Storage (as of November 5, 2023) 

2 

Reservoir 

Percent 

Current 

Live 

Storage 

Current 

Live 

Storage 

(maf) 

Live 

Storage 

Capacity 

(maf) 

Elevation 

(feet) 

Fontenelle 80 0.27 0.33 6,497.07 

Flaming 

Gorge 88 3.23 3.67 6,029.09 

Blue Mesa 72 0.59 0.83 7,491.80 

Navajo 68 1.12 1.65 6,045.46 

Lake Powell 37 8.69 23.31 3,572.32 

UC System 

Storage 47 14.02 29.79 

Total System 

Storage 43 24.94 58.48 
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Upper Colorado SWE and Observed Inflows 

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

4 
 

 

Observed Water Year 2023 

April – July 2023 

Observed Unregulated Inflow 

as of October 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 October 1, 2023 

Reservoir Inflow 

(kaf) 

Percent 

of Avg1 

Fontenelle 1,266 118 

Flaming Gorge 1,847 131 

Blue Mesa 1,060 117 

Navajo 1,218 134 

Powell 13,421 140 

1

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

5 
 

 

Most Probable November Forecast 

Water Year 2024 

April – July 2024 

Forecasted Unregulated Inflow 

as of November 1, 2023 

Reservoir Inflow 

(kaf) 

Change 

from 

October 

Percent 

of Avg1 

Fontenelle 655 -30 89 

Flaming Gorge 855 -70 89 

Blue Mesa 595 0 94 

Navajo 479 -40 76 

Powell 5,700 -535 89 

Water Year 2024 

Unregulated Inflow Forecast 

as of November 1, 2023 

Reservoir Inflow 

(kaf) 

Change 

from 

October 

Percent 

of Avg1 

Fontenelle 998 -27 93 

Flaming Gorge 1,329 -9 94 

Blue Mesa 841 -4 93 

Navajo 668 -92 73 

Powell 8,624 -776 90 

1

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

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7 
 

Upper Colorado Basin 

Hydrology and Operations 

Projections Based on 

October 2023 24-Month 

Study 

8 
 

 

 

 

 

 

Upper Basin Reservoir Operations 

Water Year 2024 

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

release 7.48 maf 

• 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. 

9 
 

 

 

 

 

 

 

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 -224 229 

Blue Mesa 36 0 -15 21 

Navajo 0 0 0 0 

Total DROA 

Volume 

(kaf) 

161 328 -239 250 

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 

10 4DROA volumes through September 2023 
11 
 

650 kaf 

550 kaf 

470 kaf 

Reclamation balanced contents between Lakes Powell and Mead by the end of the water year, as nearly as practicable, as required under the Lower 

Elevation Balancing Tier, Section 6.D.1 of the 2007 Interim Guidelines 12 
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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 

15 
 

 

16 

Most Probable End of CY 2023 Projection: 

3,570.94 feet (37% full) 

Min/Max Range: 3,570.50 to 3,570.50 feet 

Most Probable End of CY 2024 Projection: 

3,582.86 feet (41% full) 

Min/Max Range: 3,549.44 to 3,657.44 feet 
 

Most Probable End of CY 2023 Projection: 

1,067.89 feet (35% full) 

Min/Max Range: 1,067.55 to 1,068.19 feet 

Most Probable End of CY 2024 Projection: 

1,060.53 feet (32% full) 

Min/Max Range: 1,051.57 to 1,063.11 feet 

17 
Upper Colorado Basin 

Hydropower

Maintenance 

18 
Glen Canyon Dam Power Plant Unit Outage Schedule for 2024 

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Questions? 

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