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January 24-Month Study

Date: January 16, 2024

From: River Operations Group, Salt Lake City

To: All Colorado River Annual Operating Plan (AOP) Recipients

Current Reservoir Status

December Inflow

(unregulated)

(acre-feet)

Percent of

Average

(percent)

January 15

Midnight Elevation

(feet)

January 15, Midnight

Reservoir Storage

(acre-feet)

Fontenelle 35,300 110 6484.97 186,571

Flaming Gorge 44,500 135 6026.93 3,151,397

Blue Mesa 24,900 99 7489.46 573,464

Navajo 13,700 66 6042.99 1,092,498

Powell 323,800 101 3566.79 8,278,491

Expected Operations

The operation of Lake Powell and Lake Mead in the January 2024 24-Month Study is pursuant to the

December 2007 Record of Decision on Colorado River Interim Guidelines for Lower Basin Shortages and

the Coordinated Operations of Lake Powell and Lake Mead (Interim Guidelines) and reflects the draft 2024 

Annual Operating Plan (AOP). Pursuant to the Interim Guidelines, the August 2023 24-Month Study

projections of the January 1, 2024, system storage and reservoir water surface elevations set the

operational tier for the coordinated operation of Lake Powell and Lake Mead during 2024. 

The August 2023 24-Month study projected the January 1, 2024, Lake Powell elevation to be less than

3,575 feet and at or above 3,525 feet and the Lake Mead elevation to be at or above 1,025 feet. Consistent

with Section 6.C.1 of the Interim Guidelines the operational tier for Lake Powell in water year (WY) 2024 

will be the Mid-Elevation Release Tier and the water year release volume from Lake Powell will be 7.48

maf.

The 2022 Drought Response Operations Agreement (DROA) Plan1 for May 2022 through April 2023 was 

amended to suspend 2022 DROA Plan releases as of March 7, 2023. A total DROA release of

approximately 463 thousand acre-feet (kaf) occurred under the 2022 DROA Plan. Reclamation will attempt 

to maximize DROA recovery in the Upper Initial Units in WY 2023 and through April 2024. Reclamation 

will provide monthly DROA accounting, including DROA releases and recovery, which can be found online 

at: https://www.usbr.gov/ColoradoRiverBasin/documents/dcp/DROA/DROSummarySheet.pdf. 

In May of 2023, the DROA Parties agreed to the 2023 DROA Plan. The 2023 DROA Plan does not include 

any DROA releases, but rather provides for recovery of prior DROA releases from the units upstream of 

Powell.

1 For more information: https://www.usbr.gov/uc/DocLibrary/Plans/20220429-2022DroughtResponseOperationsPlanApprovalMemo-508-DOI.pdf.
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Reclamation will continue to carefully monitor hydrologic and operational conditions and assess the need

for additional responsive actions and/or changes to operations. Reclamation will continue to consult with

the Basin States, Basin Tribes, Mexico, and other partners on Colorado River operations to consider and

determine whether additional measures should be taken to further enhance the preservation of these

benefits, as well as recovery protocols, including those of future protective measures for both Lakes

Powell and Mead.

The August 2023 24-Month Study projected the January 1, 2024 Lake Mead elevation to be below 1,075

feet and above 1,050 feet. Consistent with Section 2.D.1 of the Interim Guidelines, a Shortage Condition

consistent with Section 2.D.1.a will govern the operation of Lake Mead for calendar year (CY) 2024. In

addition, Section III.B of Exhibit 1 to the Lower Basin Drought Contingency Plan (DCP) Agreement will also

govern the operation of Lake Mead for CY 2024. Lower Basin projections for Lake Mead take into 

consideration updated water orders to reflect additional conservation efforts under the LC Conservation 

Program.

The 2024 operational tier determinations for Lake Powell and Lake Mead will be documented in the 2024 

AOP, which is currently in development.

Current runoff projections into Lake Powell are provided by the National Weather Service’s Colorado Basin 

River Forecast Center. The observed unregulated inflow into Lake Powell for the month of December was

0.324 maf or 101% of the 30-year average from 1991 to 2020. The January 2024 unregulated inflow

forecast for Lake Powell is 0.315 maf or 94% of the 30-year average. The 2024 April through July

unregulated inflow forecast for Lake Powell is 4.20 maf or 66% of average. The WY 2024 unregulated 

inflow forecast for Lake Powell is 6.92 maf or 72% of average.

The draft 2024 AOP is available online at:

https://www.usbr.gov/lc/region/g4000/AOP2024/AOP24_draft.pdf.

The Interim Guidelines are available online at:

https://www.usbr.gov/lc/region/programs/strategies/RecordofDecision.pdf.

The Colorado River DCPs are available online at:

https://www.usbr.gov/ColoradoRiverBasin/dcp/finaldocs.html. 

The Upper Basin DROA is online at:

https://www.usbr.gov/ColoradoRiverBasin/dcp/droa.html. 

The Upper Basin Hydrology Summary is available online at:

https://www.usbr.gov/uc/water/crsp/studies/24Month_01_ucb.pdf.

Information on the LC Conservation Program is available online at:

https://www.usbr.gov/lc/LCBConservation.html.
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Fontenelle Reservoir

As of January 03, 2024, the Fontenelle Reservoir pool elevation is 6487.79 feet, which amounts to 61 

percent of live storage capacity. Inflows for the month of December totaled approximately 35,270 acrefeet (af) or 110 percent of average. 

Current release rate is set at 1,175 cubic feet per second (cfs). This release shall remain constant 

throughout the winter base flow period, pending significant hydrological changes or emergencies. The 

winter base flow period is typically from mid-November and ending approximately mid-March, pending 

icing conditions in the Green River downstream of the dam this coming spring.

The January final forecast for unregulated inflows into Fontenelle for the next three months projects near 

average conditions. January, February, and March Most Probable inflow volumes amount to 35,000 af (117 

percent of average), 33,000 af (118 percent of average), and 48,000 af (84 percent of average) respectively. 

The next Fontenelle Working Group meeting is April 18, 2024 at 10 AM MDT and location is pending. 

Details on the meeting will be provided as we get closer to the meeting date. Prior Fontenelle Working 

Group meeting minutes are available online on USBR’s website at 

https://www.usbr.gov/uc/water/crsp/wg/ft/ftcurrnt.html. The Fontenelle Working Group is an open public 

forum for information exchange between Reclamation and other parties associated with the operation of 

Fontenelle Reservoir.

Flaming Gorge Reservoir

As of January 8, 2024 (end of day), Flaming Gorge Reservoir pool elevation is 6027.33 feet, which amounts 

to 86 percent of live storage capacity. Unregulated inflow volume for the month of December is 

approximately 44,500 acre-feet (af), which is 135 percent of the average December unregulated inflow 

volume. 

The winter average daily release remains within the average hydrologic classification range of 1,500 cfs to 

2,400 cfs in Reach 2, measured at the Jensen USGS Gage. Current average daily release is approximately 

2,120 cfs. This data is considered the most likely scenario given the current forecast, is general, and is 

subject to changing conditions.

The January unregulated inflows into Flaming Gorge for the next three months projects near average. 

January, February, and March forecasted unregulated inflow volumes 48,000 af (119 percent of average), 

50,000 af (110 percent of average), and 95,000 af (90 percent of average), respectively. 

Reclamation is planning to hold Flaming Gorge Working Group meetings tentatively on March 21, 2024 

and April 17, 2024, at 10:00 am (and Teams virtual meeting). The location is TBD. The Flaming Gorge 

Working Group is an open public forum for information exchange between Reclamation and the 

stakeholders of Flaming Gorge Dam. The public is encouraged to attend and comment on the operations 

and plans presented by Reclamation at these meetings. Meeting notes from past Working Group 

meetings are posted on the Working Group webpage. For more information on this group and these 

meetings please contact Alex Pivarnik at (385) 475 – 8329.
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Aspinall Unit Reservoirs

As of January 8, 2024, releases from Crystal Dam are approximately 575 cfs. Flows of the Gunnison River 

in the Black Canyon are being maintained at about 545 cfs while the Gunnison Tunnel is intermittently 

diverting to fill Fairview Reservoir about 1 day every 2 weeks. Flows in the Whitewater Reach of the 

Gunnison River are about 1,060 cfs.

The unregulated inflow volume in December to Blue Mesa was 24,900 af (100 percent of average). 

Unregulated Inflow volumes forecasted for Blue Mesa for the next three months (January, February, and 

March) are projected to be: 26,000 af (96 percent of average), 30,000 af (95 percent of average) and 

28,000 af (89 percent of average), respectively. The January 24-Month Study will be reflective of these new 

forecasted inflows.

The forecasted 2024 water year unregulated inflow volume to Blue Mesa is projected to be 728,000 af (81 

percent of average). The water supply period (April-July) for 2024 is forecasted currently for an 

unregulated inflow volume of to be 490,000 af of unregulated inflow (77 percent of average).

The Aspinall Unit Operations Group is an open public forum for information exchange between 

Reclamation and the stakeholders of the Aspinall Unit. The public is encouraged to attend and comments 

on the operations and plans presented by Reclamation at these meetings. Meeting notes from past 

working Group meetings are posted on the Operations Group webpage. For more information on this 

group and these meetings please contact Erik Knight in the Grand Junction Area Office at (970) 248-0629.

The next Operations Group meeting will be held January 18, 2024 at 1:00 p.m., in person in Montrose 

Colorado. This will be an in-person meeting with an option for remote participation. Contact Erik Knight 

in the Grand Junction Area Office at (970) 248-0629 to get more information regarding this Operation 

Group meeting.

Navajo Reservoir

On January 4th, the daily average release rate from Navajo Dam was 350 cfs while reservoir inflow was 

averaging 113 cfs. The water surface elevation was 6043.4 feet above sea level. At this elevation the live 

storage is 1.10 maf (67 percent of live storage capacity) and the active storage is 0.472 maf (46 percent of 

active storage capacity). Diversions to Cutter Reservoir for the Navajo Indian Irrigation Project (NIIP) and 

the Navajo Gallup Water Supply Project (NGWSP) have ceased for the year. Due to stream flows below 

minimum bypass, 0 cfs is being diverted to the San Juan-Chama Project (SJC) above Navajo Reservoir. 

Releases from Navajo Dam are made for authorized purposes of the Navajo Unit and are pursuant to the 

Record of Decision for the Navajo Reservoir Operations. Releases target the San Juan River Recovery 

Implementation Program's (SJRIP) recommended downstream baseflow range of 500 cfs to 1,000 cfs 

through the critical habitat reach of the San Juan River (Farmington, NM to Lake Powell).

Preliminary modified unregulated inflow (MUI) into Navajo in November was 13.6 kaf (66 percent of 

average). The release averaged 340 cfs and totaled 20.7 kaf, which was 72 percent of average for the 

month. Navajo had a net storage change of -11 kaf in December.

The most probable MUI forecast for January, February, and March is 14 kaf (70 percent of average), 18 kaf 

(67 percent of average), and 42 kaf (51 percent of average), respectively. 
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The official April-July forecasts are as follows:

MIN: 235 kaf (37 percent of average)

MOST: 375 kaf (60 percent of average)

MAX: 770 kaf (123 percent of average)

Reclamation conducts Public Operations Meetings three times per year to gather input for determining 

upcoming operations for Navajo Reservoir. Input from individuals, organizations, and agencies along with 

other factors such as weather, water rights, endangered species requirements, flood control, hydro power, 

recreation, fish and wildlife management, and reservoir levels, will be considered in the development of 

these reservoir operation plans. In addition, the meetings are used to coordinate activities and exchange 

information among agencies, water users, and other interested parties concerning the San Juan River and 

Navajo Reservoir. The next meeting will be held on Tuesday, January 16th 2024 at 1:00 PM. This meeting is 

open to the public, and will be held at the Farmington Civic Center, 200 West Arrington, in Farmington, 

New Mexico (subject to change based on guidance at the time). The meeting will also have a virtual 

option.

Glen Canyon Dam / Lake Powell

Current Status

The unregulated inflow volume to Lake Powell during December was 324 kaf (101 percent of average). 

The release volume from Glen Canyon Dam in December was 600 kaf. The end of December elevation 

and storage of Lake Powell were 3,568.97 feet (131 feet from full pool) and 8.44 maf (36 percent of live 

capacity), respectively. 

Current Operations

The August 2023 24-Month study projects the January 1, 2024, Lake Powell elevation to be less than 3,575 

feet and at or above 3,525 feet and the Lake Mead elevation to be at or above 1,025 feet. Consistent with 

Section 6.C.1 of the Interim Guidelines the operational tier for Lake Powell in water year 2024 is the MidElevation Release Tier and the water year release volume from Lake Powell is 7.48 maf. 

January release volume will be 723,000 acre-feet and hourly releases will fluctuate from a low of 

approximately 8,979 cfs during the early morning hours to a high of 15,482 cfs during the afternoon and 

evening hours. The anticipated monthly release volume for February is anticipated to be 639,000 acre-feet 

and hourly releases are anticipated to fluctuate from a low of approximately 5,753 cfs during the early 

morning hours to a high of 13,947 cfs during the afternoon and evening hours. The pattern and volume 

for February will be confirmed at the end of January. 

In addition to daily scheduled fluctuations for power generation, the instantaneous releases from Glen 

Canyon Dam may also fluctuate to provide 40 megawatts (MW) of system regulation. These 

instantaneous release adjustments stabilize the electrical generation and transmission system and 

translate to a range of about 1,300 cfs above or below the hourly scheduled release rate. Under normal 

system conditions, fluctuations for regulation are typically short lived and generally balance out over the 

hour with minimal or no noticeable impacts on downstream river flow conditions.
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Releases from Glen Canyon Dam can also fluctuate beyond scheduled releases when called upon to 

respond to unscheduled power outages or power system emergencies. Depending on the severity of the 

system emergency, the response from Glen Canyon Dam can be significant, within the full range of the 

operating capacity of the power plant for as long as is necessary to maintain balance in the transmission 

system. Glen Canyon Dam currently maintains 30 MW (approximately 1,300 cfs) of generation capacity in 

reserve in order to respond to a system emergency even when generation rates are already high. System 

emergencies occur infrequently and typically require small responses from Glen Canyon Dam. However, 

these responses can have a noticeable impact on the river downstream of Glen Canyon Dam.

Inflow Forecasts and Model Projections

The forecast for water year 2024 unregulated inflow to Lake Powell, issued on January 4, 2024, by the 

Colorado Basin River Forecast Center, projects that the most probable (median) unregulated inflow 

volume in water year 2024 will be 6.92 maf (72 percent of average). 

In addition to the January 2024 24-Month Study based on the Most Probable inflow scenario, and in 

accordance with the Upper Basin DROA, Reclamation has conducted model runs in January to determine a 

possible range of reservoir elevations. The January 2024 24-Month Study probable most, minimum and 

maximum probable inflow scenarios were used to determine the range of probable outcomes. The 

probable minimum and probable maximum model runs are conducted simultaneously in January, April, 

August, and October, or when necessary to incorporate changing conditions. The probable minimum 

inflow scenario reflects a dry hydrologic condition which statistically would be exceeded 90 percent of the 

time. The most probable inflow scenario reflects a median hydrologic condition which statistically would 

be exceeded 50 percent of the time. The probable maximum inflow scenario reflects a wet hydrologic 

condition which statistically would be exceeded 10 percent of the time. There is approximately an 80 

percent probability that a future elevation will fall inside the range of the minimum and maximum inflow 

scenarios. Additionally, there are possible inflow scenarios that would result in reservoir elevations falling 

outside the ranges indicated in these reports. 

The DROA coordination will continue until either (i) the minimum probable projected elevation remains 

above 3,525 feet for 24 months or (ii) the process moves to the next step when the most probable 

projected elevation indicates Powell elevations below 3,525 feet and a Drought Response Operations Plan 

is developed. This current Plan is described above and available for review here: 

https://www.usbr.gov/ColoradoRiverBasin/dcp/droa.html.

The January forecast for WY 2024 ranges from a minimum probable of 4.95 maf (52% of average) to a 

forecasted maximum probable of 11.17 maf (116 percent of average). There is a 10 percent chance that 

inflows could be higher than the current maximum probable forecast and a 10 percent chance that inflows 

could be lower than the minimum probable forecast.

Based on the current forecast for water year 2024 of 6.92 maf unregulated inflow volume, the January 24-

Month Study projects Lake Powell elevation will end calendar year 2024 near 3559.28 feet with 

approximately 7.74 maf in storage (33 percent of capacity). Note that projections of elevation and storage 

for calendar year 2024 have significant uncertainty at this point in the season. Projections of end of 

calendar year 2024 elevation using the January minimum and maximum inflow forecast results are 

3,536.43 feet and 3,602.67 feet, respectively. The annual release volume from Lake Powell during water 

year 2024 is 7.48 maf under the Mid-Elevation Release Tier as determined under Section 6.C.1 of the 

Interim Guidelines as determined by the Department of the Interior as described above.
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Upper Colorado River Basin Hydrology

Upper Colorado River Basin regularly experiences significant year to year hydrologic variability. The 30-

year average was updated in October 2022 from 1981 through 2010 to 1991 through 2020. Shifting the 

period of record decreased the average unregulated inflow 1.20 maf. The period 2000-2022 is the lowest 

23-year period since the closure of Glen Canyon Dam in 1963, with an average unregulated inflow of 8.29 

maf, or 93 percent of the 30-year average (1991-2020). (For comparison, the 1991-2020 total water year 

average is 9.60 maf.) The unregulated inflow during the 2000-2022 period has ranged from a low of 2.64 

maf (28 percent of average) in water year 2002 to a high of 15.97 maf (166 percent of average) in water 

year 2011. In water year 2021 unregulated inflow volume to Lake Powell was 3.50 maf (36 percent of 

average), the second driest year on record above 2002. Under the current most probable forecast, the 

total water year 2024 unregulated inflow to Lake Powell is projected to be 6.92 maf (72 percent of 

average).

At the beginning of water year 2024, total system storage in the Colorado River Basin was 25.27 maf (43 

percent of 58.48 maf total system capacity). This is an increase of 5.72 maf over the total storage at the 

beginning of water year 2023 when total system storage was 19.55 maf (33 percent of capacity). Since the 

beginning of water year 2000, total Colorado Basin storage has experienced year to year increases and 

decreases in response to wet and dry hydrology, ranging from a high of 94 percent of capacity at the 

beginning of 2000 to the beginning of water year 2023 with 19.55 maf (33 percent of capacity). Based on 

current inflow forecasts, the current projected end of water year 2024 total Colorado Basin reservoir 

storage is approximately 23.61 maf (40.4 percent of total system capacity). The actual end of water year 

2024 system storage may vary from this projection, primarily due to uncertainty regarding this season’s 

runoff and reservoir inflow.