Upper Colorado Region Weekly Hydrology Summary Facilities … · 2020. 7. 20. · Upper Colorado...
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Upper Colorado Region Weekly Hydrology Summary Facilities Status Update for the week ending November 27, 2020 Upper Colorado River Basin WY 2021 forecasted unregulated inflow decreased to 6.25 maf (58% of avg). We are experiencing record‐breaking drought in the Upper Colorado. o The last six month period is the driest on record. o August 2019 with –20 kaf unregulated inflow (‐4% of avg), is the second driest on record, following August 2002. o September 2019 with 47 kaf unregulated inflow (12% of avg) is the second driest on record, following September 2018 (1 kaf). o October 2019 with 91 kaf (18% of avg) is the driest on record, followed by October 2001 (159 kaf). o Current conditions resemble 2002, 2012, 2013 and the beginning of 2018. The August 2020 24‐MS set WY2021 operating tier in the Upper Elevation Balancing Tier of the 2007 IG. The November most probable release in WY2021 is 8.234 maf with a balancing release of ~4,000 af. The October min and max studies both show a WY2021 release of 8.23 maf. Green River Basin Flaming Gorge operations are in a winter base flow period which started on December 1. Average daily releases will be 1000 cfs, +25% of the calculated base flow to meet Moderately Dry hydrologic condition lower targets in Reach 2, 1,100 cfs to 1,500 cfs (includes flows from the Yampa River). Fontenelle’s releases are currently set at 825 cfs. This release is scheduled to be maintained through the Fall/Winter operation period, which typically ends in March when ice on the Green River begins to thaw. Gunnison River Basin Releases from Aspinall are 400 cfs. Aspinall’s operations are in base flow mode. We are maintaining Whitewater flows above 750 cfs and Black Canyon flows above 300 cfs. On October 31, 2020 the Gunnison Tunnel terminated diversions for the 2020 irrigation season. About every 2 weeks throughout the winter months, the Gunnison Tunnel will make a small diversion to refill Fairview Reservoir. As of yesterday, Whitewater flows were 837 cfs and Black Canyon flows were 382 cfs. Blue Mesa will not fill this year due to the below normal forecast for the spring runoff. Based on the current conditions and projected inflows, Blue Mesa has already reached its peak elevation for the year which was 7492.87 feet which occurred on June 19, 2020. The current elevation is now 7464.51 feet and gradually increasing. This is 54 feet from the full pool elevation of 7519.6 feet. Current storage is 399,627 acre‐ feet which is 48 percent of full capacity. San Juan River Basin The NIIP has shut off diversions for the season. The San Juan‐Chama project is not currently diverting from the basin above the reservoir. The river flow measured at the Animas River at Farmington USGS gage was at 196 cfs. River flow at the San Juan River at Four Corners USGS gage was 525 cfs. 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. The release targets the San Juan River Recovery Implementation Program's 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). Current modeling shows the release from Navajo will most likely vary between 250 and 500 cfs to accomplish this over the winter. The currently calculated weekly baseflow is 521, which is within the target range.
Transcript of Upper Colorado Region Weekly Hydrology Summary Facilities … · 2020. 7. 20. · Upper Colorado...
Upper Colorado Region Weekly Hydrology Summary Facilities Status Update for the week ending November 27, 2020 Upper Colorado River Basin
WY 2021 forecasted unregulated inflow decreased to 6.25 maf (58% of avg). We are experiencing record‐breaking drought in the Upper Colorado.
o The last six month period is the driest on record. o August 2019 with –20 kaf unregulated inflow (‐4% of avg), is the second driest on record, following
August 2002. o September 2019 with 47 kaf unregulated inflow (12% of avg) is the second driest on record, following
September 2018 (1 kaf). o October 2019 with 91 kaf (18% of avg) is the driest on record, followed by October 2001 (159 kaf). o Current conditions resemble 2002, 2012, 2013 and the beginning of 2018.
The August 2020 24‐MS set WY2021 operating tier in the Upper Elevation Balancing Tier of the 2007 IG. The November most probable release in WY2021 is 8.234 maf with a balancing release of ~4,000 af. The October min and max studies both show a WY2021 release of 8.23 maf.
Green River Basin Flaming Gorge operations are in a winter base flow period which started on December 1. Average daily
releases will be 1000 cfs, +25% of the calculated base flow to meet Moderately Dry hydrologic condition lower
targets in Reach 2, 1,100 cfs to 1,500 cfs (includes flows from the Yampa River).
Fontenelle’s releases are currently set at 825 cfs. This release is scheduled to be maintained through the Fall/Winter operation period, which typically ends in March when ice on the Green River begins to thaw.
Gunnison River Basin
Releases from Aspinall are 400 cfs. Aspinall’s operations are in base flow mode. We are maintaining Whitewater flows above 750 cfs and Black Canyon flows above 300 cfs. On October 31,
2020 the Gunnison Tunnel terminated diversions for the 2020 irrigation season. About every 2 weeks throughout the winter months, the Gunnison Tunnel will make a small diversion to refill Fairview Reservoir. As of yesterday, Whitewater flows were 837 cfs and Black Canyon flows were 382 cfs.
Blue Mesa will not fill this year due to the below normal forecast for the spring runoff. Based on the current conditions and projected inflows, Blue Mesa has already reached its peak elevation for the year which was 7492.87 feet which occurred on June 19, 2020. The current elevation is now 7464.51 feet and gradually increasing. This is 54 feet from the full pool elevation of 7519.6 feet. Current storage is 399,627 acre‐feet which is 48 percent of full capacity.
San Juan River Basin
The NIIP has shut off diversions for the season. The San Juan‐Chama project is not currently diverting from the basin above the reservoir. The river flow
measured at the Animas River at Farmington USGS gage was at 196 cfs. River flow at the San Juan River at Four Corners USGS gage was 525 cfs.
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. The release targets the San Juan River Recovery Implementation Program's 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). Current modeling shows the release from Navajo will most likely vary between 250 and 500 cfs to accomplish this over the winter. The currently calculated weekly baseflow is 521, which is within the target range.
Upper Colorado Region Weekly Hydrology Summary
ReservoirElevation
(ft)Live Storage
(1000 AF)% of Live Capacity
Avg Daily Unreg Inflow
(cfs)Daily Release
(cfs)Lake Powell 3,587.18 10,567 43% 1,788 12,059Blue Mesa 7,464.48 399 48% 322 318
Flaming Gorge 6,025.27 3,170 84% 226 1,018Fontenelle 6,487.50 211 61% 382 825Navajo** 6,038.14 1,093 64% 71 367
Elephant Butte 4,297.53 102 5% 376 1Current as of: 12/3/2020 **Unreg inflow is actually Modified Unreg Inflow
Selected Reservoir Inflows - Forecasted & Water Year to December 4, 2020
Reservoir
December Final
Forecast WY2021
Unregulated Inflow
(1000 AF)
December Final
Forecast WY2021
Unregulated Inflow
(% Average)
November Unregulated
Inflow Observed (1000 AF)
November Unregulated
Inflow Observed
(% Average)
Lake Powell 6,252 58% 261 55%Blue Mesa 660 69% 25 79%Fontenelle 799 74% 32 77%
Flaming Gorge 986 68% 36 70%Navajo 613 57% 16.9 50%
This hydrologic information is provided weekly to summarize the hydrologic conditions in the Upper Colorado Region. If additional information is required, please contact Mark Delorey ([email protected]) in the Water Management Group, Power
Office.Selected Reservoir Status - Report Date: December 4, 2020
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Upper Colorado Region Weekly Hydrology Summary
% AVG PRECIPITATION Conditions Map
% AVERAGE PRECIPITATION - Upper Colorado Region - December 4, 2020
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Upper Colorado Region Weekly Hydrology Summary
6-10 Day Temperature 6-10 Day Precipitation
Snow Conditions Month to Date Precipitation
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Lake Powell Reservoir and Glen Canyon DamDaily Unregulated Inflow
Water Year 2021
GC Unreg Inflow 30-Year Avg GC Unreg Inflow WY2020 GC Unreg Inflow WY2021
3,530
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Lake Powell Reservoir and Glen Canyon DamDaily Total Release and Elevation
Water Year 2021
GC Release WY2020 GC Release WY2021 GC Elev WY2020 GC Elev WY2021
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Blue Mesa Dam and Reservoir Unregulated Inflow Daily Average
Water Year 2021
BM Unreg Inflow 30-Year Avg BM Unreg Inflow WY2020 BM Unreg Inflow WY2021
7,400
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Crystal Dam and Reservoir Daily Total Release and Blue Mesa Dam and Reservoir Elevation
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CY Release WY2020 CY Release WY2021 BM Elev WY2020 BM Elev WY2021
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Flaming Gorge Dam and Reservoir Unregulated Inflow Daily Average
Water Year 2021
FG Unreg Inflow 30-Year Avg FG Unreg Inflow WY2020 FG Unreg Inflow WY2021
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Flaming Gorge DamDaily Total Release and Elevation
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FG Release WY2020 FG Release WY2021 FG Elev WY2020 FG Elev WY2021
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Navajo Dam and Reservoir Unregulated Inflow Daily Average
Water Year 2021
NV Mod Unreg Inflow 30-Year Avg NV Mod Unreg Inflow WY2020 NV Mod Unreg Inflow WY2021
6,010
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Navajo DamDaily Total Release and Elevation
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NV Release WY2020 NV Release WY2021 NV Elev WY2020 NV Elev WY2021
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