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Current Dam Operations

 

Current Status

Last Updated: January 14, 2022

 

The Upper Basin Drought Response Operations Agreement (DROA) provisions to protect a target elevation at Lake Powell of 3,525 feet have been incorporated into the January 2022 24-Month Study and include an adjusted monthly release volume pattern for Glen Canyon Dam that will hold back a total of 0.350 maf in Lake Powell from January through April. There are continued discussions when and how that same amount of water (0.350 maf) will be released later in the water year. The annual release volume from Lake Powell for water year 2022 will continue to be 7.48 maf. If future projections indicate the monthly adjustments are insufficient to protect Powell’s elevation, Reclamation will again consider additional water releases from the upstream initial units of the Colorado River Storage Project later this year. More information is available here: https://www.usbr.gov/newsroom/#/news-release/4073

 

The unregulated inflow volume to Lake Powell during December was 266 thousand acre-feet (kaf) (83 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 3,537.33 feet (163 feet from full pool) and 7.02 million acre-feet (maf) (29 percent of live capacity), respectively.

 

To view the most current reservoir elevation projections, click on: Lake Powell Elevation Projections.
To view the most current monthly release projections, click on: Lake Powell Release Projections.
To view the 2022 progession of snowpack above Lake Powell, click on Lake Powell Snow Chart.
To view the current inflow forecast relative to past inflows, click on Lake Powell Inflow Forecast.

 

Current Operations

The operating tier for water year 2022 (October 2021 through September 2022) was established in August 2021 as the Mid-Elevation Release Tier consistent with Section 6.C.1 of the Interim Guidelines. The August 2021 24-Month study projected the January 1, 2022, 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 2022 will be the Mid-Elevation Release Tier and the water year release volume from Lake Powell will be 7.48 maf.

 

The January anticipated release is 673 kaf with fluctuations between about 7,457 cfs to around 13,464 cfs on weekdays and Saturdays. The February anticipated release is 539 kaf with fluctuations between about 6,500 cfs to around 11,351 cfs on weekdays and Saturdays, with a Sunday peak of 11,000 cfs. The March anticipated release is 575 kaf.

 

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 1,100 cfs above or below the hourly scheduled release rate. Under system normal 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.

 

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 800 cfs) of generation capacity in reserve in order to respond to a system emergency even when generation rates are already high. System emergencies occur fairly 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 2022 unregulated inflow to Lake Powell, issued on January 5, 2022, by the Colorado Basin River Forecast Center, projects that the most probable (median) unregulated inflow volume this year will be 8.77 maf (91 percent of average).

 

In addition to the January 2022 24-Month Study based on the Most Probable inflow scenario, and in accordance with the Drought Response Operational Agreement (DROA)), Reclamation has conducted model runs in January to determine a possible range of reservoir elevations under probable minimum and probable maximum inflow scenarios. Probable minimum and probable maximum model runs are conducted in January, April, August, and October. The probable minimum inflow scenario reflects a dry hydrologic condition which statistically would be exceeded 90% of the time. The most probable inflow scenario reflects a median hydrologic condition which statistically would be exceeded 50% of the time. The probable maximum inflow scenario reflects a wet hydrologic condition which statistically would be exceeded 10% of the time. There is approximately an 80% 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.

 

The November forecast for water year 2022 ranges from a minimum probable of 5.00 maf (52% of average) to a maximum probable of 14.02 maf (146% of average) with the most probable forecast for water year 2022 of 7.80 maf (81% of average). There is a 10% chance that inflows could be higher than the current maximum probable forecast and a 10% chance that inflows could be lower than the minimum probable forecast.

 

Based on the current forecast of 8.77 maf unregulated inflow, the January 24-Month Study projects Lake Powell elevation will end water year 2022 near 3,552.04 feet with approximately 7.73 maf in storage (32 percent of capacity). Note that projections of elevation and storage for water year 2022 have significant uncertainty at this point in the season. Projections of end of water year 2022 elevation using the minimum and maximum probable inflow forecast results from the January 2022 model runs are 3,526.08 feet and 3,596.06 feet, respectively. Under these scenarios, there is a 10 percent chance that inflows will be higher, resulting in higher elevation, and 10 percent chance that inflows will be lower, resulting in lower elevation. The annual release volume from Lake Powell during water year 2022 will be 7.48 maf as determined under Section 6.C.1 of the Interim Guidelines.

 

Upper Colorado River Basin Hydrology

Upper Colorado River Basin regularly experiences significant year to year hydrologic variability. During the 22-year period 2000 to 2021, however, the unregulated inflow to Lake Powell, which is a good measure of hydrologic conditions in the Colorado River Basin, was above average in only 4 out of the past 22 years. The period 2000-2021 is the lowest 21-year period since the closure of Glen Canyon Dam in 1963, with an average unregulated inflow of 8.46 maf, or 88% 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 (24% of average) in water year 2002 to a high of 15.97 maf (147% of average) in water year 2011. In water year 2021 unregulated inflow volume to Lake Powell was 3.50 maf (36% of average), the second driest year on record above 2002. Under the current most probable forecast, the total water year 2022 unregulated inflow to Lake Powell is projected to be 8.77 maf (91% of average).

 

At the beginning of water year 2022, total system storage in the Colorado River Basin was 22.93 maf (38% of 59.6 maf total system capacity). This is a decrease of 6.01 maf over the total storage at the beginning of water year 2021 when total system storage was 28.94 maf (49% 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% of capacity at the beginning of 2000 to the now current level of 88% of capacity at the beginning of water year 2022. Based on current inflow forecasts, the current projected end of water year total Colorado Basin reservoir storage for water year 2022 is approximately 22.63 maf (38% of total system capacity). The actual end of water year 2022 system storage may vary from this projection, primarily due to uncertainty regarding this season’s runoff and reservoir inflow.