GCDAMP Technical Work 

Group

Basin Hydrology and Operations

June 16, 2021
Upper Basin Storage (as of June 14, 2021)

Reservoir

Percent 

Current 

Live 

Storage

Current 

Live 

Storage

(maf)

Live 

Storage 

Capacity 

(maf)

Elevation

(feet)

Fontenelle 64 0.27 0.33 6,489.80

Flaming 

Gorge 84 3.15 3.75 6,024.63

Blue Mesa 47 0.39 0.83 7,463.47

Navajo 67 1.13 1.70 6,041.47

Lake Powell 35 8.46 24.32 3,561.76

UC System 

Storage 43 13.47 31.09

2
Precipitation: June and Seasonal

3
Soil Moisture Comparison: June 2020 and 2021

4
Current SWE and Observed UC Runoff

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

5
Most Probable June Final Spring Forecast and 

WY 2021 Forecast

April – July 2021

Forecasted Unregulated Inflow

as of June 2, 2021

Reservoir

Unregulated 

Inflow

(kaf)1

Percent 

of 

Average2

Fontenelle 345 48

Flaming Gorge 395 40

Blue Mesa 310 46

Navajo 335 46

Powell 1,800 25

Water Year 2021

Forecasted Unregulated Inflow

as of June 3, 2021

Reservoir

Unregulated 

Inflow

(kaf)

Percent 

of 

Average1

Fontenelle 589 54

Flaming Gorge 677 46

Blue Mesa 506 53

Navajo 463 43

Powell 3,367 31

Powell decreased 1.53 maf from April Forecast of 4.9 maf (45%)

1 April-July includes observed volumes for April and May. 

2 Percent of average based on the period of record from 1981-2010.

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7
Upper Colorado Basin

Projected Operations 

for Water Year 2021 

Based on June 2021 

Modeling

8
Drought Response Operations Agreement (DROA)

• Formal notification that the January 2021 Minimum Probable 24 Month Study (24-MS) run projected 

Powell to fall below 3,525 feet in 2022 was provided pursuant to the DROA.

• February through June Minimum Probable 24-MS continued to indicate elevations below 3,525 feet in 2022.

• Operating under enhanced monitoring and coordination under the DROA.

• Operating with monthly analysis of min/most/max with the parties specified in the DROA. 

• The May most probable 24-Month Study elevation projected Lake Powell reaching 3,525.57 feet as 

early as March 2022.

• The June most probable 24-Month Study elevation projects Lake Powell reaching below 3,525 feet as 

early as February 2022

• The UCRC announced on May 20, 2021 that the parties are beginning the process of developing a 

drought response operations plan in accordance with the DROA.

• Consultation with the states of Arizona, California, and Nevada will occur prior to finalization of the developed plan.

• The developed plan will be finalized if Reclamation’s April 24-Month Study Most Probable forecast shows Lake Powell 

falling to a target elevation of 3,525 feet or below within a 12-month period.

• If the Secretary of Interior determines there is imminent need to protect Lake Powell elevations from dropping below 

3,525 feet, she has the discretion to take emergency action after consulting with the Colorado River Basin States.

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10
Lake Powell & Lake Mead Operational Table

Projected Tiers for Water/Calendar Year 20221 

based on June 24-Month Study with an 8.23 maf release

11 1 Lake Powell and Lake Mead operational tier determinations will be based on the August 2021 24-Month Study projections and documented in the draft 2022 AOP.
Lake Powell WY 2022 Operating Tier Scenarios

Based on June 2021 24-Month Study Inflow Scenarios

Inflow 

Scenario

Operating Tier/

Release Volume

June DROA* 

Minimum Probable

Lower Elevation Balancing

7.00 maf

June Most Probable Mid-Elevation Release

7.48 maf

June DROA* 

Maximum Probable

Mid-Elevation Release

7.48 maf

12

*The Drought Response Operations Agreement (DROA) can be found online at: 

https://www.usbr.gov/dcp/finaldocs.html.
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16
Lake Mead End of Month Elevations 

Projections from the June 2021 24-Month Study Inflow Scenarios

17
Glen Canyon Dam Power Plant Unit Outage Schedule for 2021

18
Glen Canyon Dam Power Plant Unit Outage Schedule for 2022

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21
Water Quality

22
Temperature Profile of Lake Powell near Glen Canyon Dam

5/14/2021

23
Cross Sectional Temperature Profile of Lake Powell

5/14/2021

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Questions/Discussion

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