Lake Powell Water Supply Outlook, January 1, 2023

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Ashley Nielson
NOAA, National Weather Service
Colorado Basin River Forecast Center
Salt Lake City, Utah
www.cbrfc.noaa.gov

Contents

Lake Powell Sub-Basin Summaries




*Median of forecasts within each basin.





*Median of forecasts within each basin.







*Median of forecasts within each basin.




Upper Green Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Yampa/White Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Duchesne Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Lower Green Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Upper Colorado Mainstem Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Gunnison Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Dolores Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

San Juan Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.


Upper Green Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
Green
Daniel, Nr, Warren Bridge, At April-July140 190 230 90 285 330
Pine Ck
Fremont Lk, Abv April-July70 80 95 94 105 120
New Fork
Big Piney, Nr April-July190 270 325 92 395 490
Green
Fontenelle Reservoir, Fontenelle, Nr April-July350 555 700 95 820 1050
Big Sandy
Farson, Nr April-July30 41 50 100 58 73
Green
Green River, Wy, Nr April-July340 550 700 95 850 1070
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July28 38 55 106 72 84
Viva Naughton Reservoir April-July35 55 75 103 108 130
Blacks Fork
Robertson, Nr April-July58 67 90 102 103 121
Ef Smiths Fork
Stateline Reservoir, Robertson,nr April-July19 24 30 107 35 40
Green
Flaming Gorge Reservoir April-July490 740 950 98 1250 1570


Yampa/White Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
Yampa
Steamboat Springs April-July200 255 310 119 345 405
Elk
Milner, Nr April-July285 340 425 129 455 505
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July60 70 100 141 115 138
Yampa
Maybell, Nr April-July730 940 1150 125 1300 1520
Little Snake
Slater, Nr April-July120 140 180 116 210 230
Lily, Nr April-July235 290 400 123 485 630
Yampa
Deerlodge Park April-July950 1200 1540 129 1780 2050
White
Meeker, Nr April-July225 250 290 112 330 460
Watson, Nr April-July230 260 305 113 355 515


Duchesne Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
Big Brush Ck
Vernal, Nr, Red Fleet Res, Abv April-July12 17 21 107 24 32
Ashley Ck
Vernal, Nr April-July27 38 50 109 56 77
West Fork Duchesne
Vat Diversion, Blo April-July11 16 20 118 27 35
Duchesne
Tabiona, Nr April-July72 87 110 107 135 160
Rock Ck
Upper Stillwater Reservoir April-July50 60 75 104 98 120
South Fork Rock Ck
Docs Div, Blo April-July4 5.5 7 96 10 12
Rock Ck
Mountain Home, Nr April-July60 73 90 103 120 142
Currant Ck
Currant Ck Reservoir April-July10 14 22 124 30 40
Strawberry
Strawberry Reservoir, Soldier Springs April-July30 40 65 108 85 115
Starvation Reservoir, Duchesne, Nr April-July50 70 110 117 150 210
Duchesne
Duchesne, Nr, Knight Div, Abv April-July135 160 200 106 255 300
Lake Fork
Moon Lake Reservoir, Mtn Home, Nr April-July42 50 65 102 80 105
Yellowstone
Altonah, Nr April-July44 55 65 108 78 100
Whiterocks
Whiterocks, Nr April-July33 45 56 110 64 90
Uinta
Neola, Nr April-July45 65 83 115 94 125
Duchesne
Myton April-July175 230 340 111 485 600
Randlett, Nr April-July185 245 390 111 540 675


Lower Green Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
White
Blo Tabbyune Ck, Soldier Summit, Nr April-July7.5 11.5 19 151 25 30
Fish Ck
Scofield, Nr, Reservoir, Abv April-July23 29 40 154 48 58
Price
Scofield Reservoir, Scofield, Nr April-July30 41 55 162 68 85
Green
Green River, Ut April-July1900 2450 3200 114 3850 4950
Huntington Ck
Electric Lake April-July11 14 17 150 21 26
Power Plant, Blo April-July35 42 50 125 61 71
Seeley Ck
Joes Vly Reservoir, Orangeville, Nr April-July40 50 58 114 70 85
Ferron Ck
Ferron, Nr April-July26 32 36 103 46 57
Muddy Ck
Emery, Nr April-July13 15 17 93 23 30


Upper Colorado Mainstem Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
Colorado
Lake Granby, Granby, Nr April-July160 200 225 100 250 300
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July30 46 60 120 72 90
Fraser
Winter Park April-July13.5 17 20 108 22 25
Williams Fork
Williams Fork Reservoir, Parshall April-July58 76 88 92 100 118
Muddy Ck
Wolford Mountain Reservoir April-July28 42 58 112 72 90
Blue
Dillon Reservoir April-July110 135 160 96 185 210
Green Mtn Reservoir April-July180 230 270 96 315 360
Colorado
Kremmling, Nr April-July580 745 880 101 1020 1210
Eagle
Gypsum, Blo April-July225 275 320 96 380 470
Colorado
Dotsero, Nr April-July950 1200 1420 101 1650 2000
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July92 115 132 98 150 182
Roaring Fork
Glenwood Springs April-July470 560 635 97 750 960
Colorado
Glenwood Springs, Blo April-July1460 1800 2100 101 2450 3000
Cameo, Nr April-July1630 2000 2300 101 2700 3400
Cisco, Nr April-July3000 3600 4150 102 5000 6800
Lake Powell, Glen Cyn Dam, At April-July4440 5170 6700 105 8380 11530


Gunnison Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
Taylor
Taylor Park Reservoir April-July75 86 97 103 111 149
Almont April-July120 138 152 103 176 245
East
Almont April-July119 153 166 94 215 275
Gunnison
Gunnison, Nr April-July245 315 335 96 440 585
Tomichi Ck
Gunnison April-July31 49 60 90 71 107
Lake Fork
Gateview April-July85 97 110 93 119 152
Gunnison
Blue Mesa Reservoir April-July460 535 605 95 725 985
Morrow Point Reservoir April-July505 585 655 95 795 1050
Crystal Reservoir April-July580 655 735 95 900 1170
Muddy Ck
Paonia Reservoir, Bardine, Nr April-July61 73 85 105 93 156
Nf Gunnison
Somerset, Nr April-July210 245 275 104 310 455
Surface Ck
Cedaredge April-July11.3 14.8 15.9 109 17.7 32
Uncompahgre
Ridgway Reservoir April-July68 83 90 98 102 122
Colona April-July82 105 113 94 131 163
Delta April-July61 83 90 95 101 149
Gunnison
Grand Junction, Nr April-July1000 1190 1300 98 1620 2180


Dolores Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
Dolores
Dolores April-July136 183 225 105 265 400
Mcphee Reservoir April-July163 215 260 102 325 495
San Miguel
Placerville, Nr April-July76 102 115 100 128 160
Dolores
Cisco, Nr April-July290 390 500 99 570 960


San Juan Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
San Juan
Pagosa Springs April-July130 157 185 95 210 300
Carracas, Nr April-July210 260 305 92 355 540
Navajo Reservoir, Archuleta, Nr April-July385 465 570 90 670 1010
Bluff, Nr April-July670 840 1000 90 1190 1780
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July32 41 45 92 52 78
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July39 48 54 93 63 92
Little Navajo
Oso Div Dam,bl,chromo,nr April-July3.2 4.2 5 82 6.9 11
Piedra
Arboles, Nr April-July102 134 165 91 193 285
Los Pinos
Vallecito Reservoir, Bayfield, Nr April-July128 154 170 96 192 240
Animas
Durango April-July275 340 385 100 435 555
Florida
Lemon Reservoir, Durango, Nr April-July34 40 48 100 57 75
La Plata
Hesperus April-July11.7 16.9 20 87 24 35
Mancos
Mancos, Nr April-July12 15.4 17 99 21 39

Differences between the full period forecasts and the residual forecasts may not exactly equal the actual observed volumes due to rounding conventions (see Definitions section).

Green End of Month Reservoir Contents (kaf)

EOM
Contents		Percent
EOM
Average		Percent
Usable
Capacity		Last Year
EOM		Last Year
%Average		EOM
Average		Usable
Capacity
untitled Green
Fontenelle Reservoir, Fontenelle, Nr 193.7 98 58 203.0 103 198.0 334.0
untitled Big Sandy
Big Sandy Reservoir, Nr Farson 6.5 41 17 6.1 38 15.9 38.3
Blacks Fork
Meeks Cabin 7.7 75 26 9.0 88 10.2 29.9
untitled Ef Smiths Fork
Stateline Reservoir, Robertson,nr 5.6 103 40 5.1 94 5.4 13.9
untitled Green
Flaming Gorge Reservoir 2540.1 82 68 2899.9 93 3109.5 3749.0
untitled Strawberry
Strawberry Reservoir, Soldier Springs 797.4 98 72 811.3 100 810.6 1105.9
Starvation Reservoir, Duchesne, Nr 122.6 92 74 125.3 94 133.2 165.3
untitled Rock Ck
Upper Stillwater Reservoir 9.4 85 30 28.8 260 11.1 31.4
untitled Lake Fork
Moon Lake Reservoir, Mtn Home, Nr 23.2 128 64 21.7 119 18.2 36.5
untitled Big Brush Ck
Red Fleet Reservoir, Vernal, Nr 9.1 53 35 9.9 58 17.2 25.7
untitled Price
Scofield Reservoir, Scofield, Nr 12.6 52 19 16.3 67 24.2 65.8
untitled Seeley Ck
Joes Vly Reservoir, Orangeville, Nr 29.8 79 48 21.2 56 37.7 62.5
untitled Huntington Ck
Electric Lake 11.1 61 35 11.4 63 18.1 31.5
untitled
TOTAL 3768.8 85 66 4168.9 95 4409.3 5689.6


Upper Colorado End of Month Reservoir Contents (kaf)

EOM
Contents		Percent
EOM
Average		Percent
Usable
Capacity		Last Year
EOM		Last Year
%Average		EOM
Average		Usable
Capacity
untitled Colorado
Lake Granby, Granby, Nr 481.5 123 98 368.9 94 392.1 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 7.4 94 81 6.9 88 7.8 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 45.6 65 47 62.5 89 69.9 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 40.3 88 61 31.3 69 45.6 66.0
untitled Blue
Dillon Reservoir 210.9 93 83 196.4 86 227.3 254.0
Green Mtn Reservoir 83.9 102 57 65.0 79 82.6 146.9
untitled Homestake Ck
Homestake Reservoir 29.7 92 69 29.0 90 32.4 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 66.7 90 65 58.2 79 73.9 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 8.9 75 27 5.5 46 12.0 32.9
untitled Taylor
Taylor Park Reservoir 66.3 96 62 58.7 85 68.9 106.2
untitled Gunnison
Blue Mesa Reservoir 290.2 54 35 230.9 43 536.0 827.9
Morrow Point Reservoir 102.9 93 88 105.7 96 110.1 117.0
Crystal Reservoir 16.6 109 94 16.1 106 15.1 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 1.1 47 6 0.7 30 2.3 16.7
untitled Uncompahgre
Ridgway Reservoir 67.8 101 82 64.6 96 67.0 83.0
untitled Dolores
Mcphee Reservoir 186.8 73 49 164.8 65 255.4 381.1
untitled
TOTAL 1706.5 85 61 1465.3 73 1998.4 2790.6
Colorado
Lake Powell 5530.5 37 23 6713.1 45 14835.5 24322.0
untitled
TOTAL 5530.5 37 23 6713.1 45 14835.5 24322.0


San Juan End of Month Reservoir Contents (kaf)

EOM
Contents		Percent
EOM
Average		Percent
Usable
Capacity		Last Year
EOM		Last Year
%Average		EOM
Average		Usable
Capacity
untitled Los Pinos
Vallecito Reservoir, Bayfield, Nr 66.7 100 53 35.2 53 66.6 125.4
untitled San Juan
Navajo Reservoir, Archuleta, Nr 852.4 66 50 871.8 68 1287.8 1696.0
untitled Florida
Lemon Reservoir, Durango, Nr 16.8 94 42 13.2 74 17.9 39.8
untitled
TOTAL 936.0 68 50 920.3 67 1372.3 1861.2

Precipitation Maps




Definitions

10% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 10% chance of being exceeded. Previously referred to as "Reasonable Maximum Forecast".

50% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 50% chance of being exceeded. Previously referred to as "Most Probable Forecast".

90% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 90% chance of being exceeded. Previously referred to as "Reasonable Minimum Forecast".

Acre-Foot (af): The volume equal to one acre covered one foot deep (43,560 cubic feet). See kaf below.

Average: The arithmetic mean. The sum of the values divided by the number of values. Values from 1991-2020 are used for this publication.

Categories: Much Above Average=Greater than 130%, Above Average=111-130%, Near Average=90-110%, Below Average=70-89%, Much Below Average=Less than 70%.

CBRFC: Colorado Basin River Forecast Center.

Forecast Period: The period from April 1 through July 31, unless otherwise noted.

kaf: Thousand Acre-Feet. See Acre-Foot above.

Inflow: The volume of water that flows into a reservoir or lake.

Median: The middle value of an ordered set of values. Half of the values are higher and half of the values are lower. When the set contains an even number of values the median is the average of the two middle numbers.

NOAA: National Oceanic and Atomospheric Administration.

NWS: National Weather Service.

Rounding Conventions:
RangeRound to
0-1.990.01
2.0-19.90.1
20-1991.0
200-9995.0
1000+3 significant digits


Streamflow: The volume of water that flows past a specific stream site.

Water Year: The 12-month period, October 1 through September 30. The water year is designated by the calendar year in which it ends. Thus, the year ending September 30, 2008, is called the "2008 water year."


Additional Information

Water supply forecasts take into consideration present hydrometeorological conditions and use average basin temperatures and precipitation for the forecast period. As the forecast season progresses, a greater portion of the future hydrologic and climatic uncertainty becomes known and monthly forecasts become more accurate. For more information on the tools we use, consult Water Supply Forecasting Tools.

Volume forecasts represent adjusted flows; that is, observed flows with upstream water use taken into account. Adjusted flows will closely approximate natural or unimpaired flows. However, not all upstream diversions or impoundments are measured or quantifiable. For specific adjustments used with each forecast point, consult the Guide to Water Supply Forecasting.

The Water Supply Outlook is issued monthly January through May by the Colorado Basin River Forecast Center. It represents a coordinated effort between the National Weather Service, Natural Resources Conservation Service, Bureau of Reclamation, U.S. Geological Survey and local water district managers.

Note: Data used in this report are provisional and are subject to revision.

For more information, or to be included on the mailing list, please contact:

Colorado Basin River Forecast Center
2242 W North Temple
Salt Lake City, UT 84116
(801) 524-5130
www.cbrfc.noaa.gov