New 1991-2020 Averages being used this year.
Lake Powell Water Supply Outlook, May 1, 2022

Lake Powell Water Supply Outlook, May 1, 2022

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-July160 180 200 78 220 240
May-July150 170 190 81 210 230
Pine Ck
Fremont Lk, Abv April-July50 57 70 69 78 87
May-July48 55 68 69 76 85
New Fork
Big Piney, Nr April-July125 155 200 56 235 295
May-July110 140 185 56 220 280
Green
Fontenelle Reservoir, Fontenelle, Nr April-July320 385 475 65 540 620
May-July270 335 425 65 490 570
Big Sandy
Farson, Nr April-July22 25 33 66 42 48
May-July20 23 31 67 40 46
Green
Green River, Wy, Nr April-July310 380 465 63 540 620
May-July260 330 415 64 490 570
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July17.6 19.6 25 48 31 37
May-July14 16 21 46 27 33
Viva Naughton Reservoir April-July24 26 32 44 40 48
May-July16 18 24 40 32 40
Blacks Fork
Robertson, Nr April-July50 53 63 72 73 86
May-July47 50 60 72 70 83
Ef Smiths Fork
Stateline Reservoir, Robertson,nr April-July16.4 17.4 20 71 23 27
May-July15 16 18.6 72 22 26
Green
Flaming Gorge Reservoir April-July395 455 550 57 665 765
May-July330 390 485 58 600 700


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
Stagecoach Rsvr, Abv April-July19 20 21 78 22 24
May-July15 16 17 81 17.5 20
Steamboat Springs April-July162 182 200 77 220 245
May-July140 160 178 81 200 225
Elk
Milner, Nr April-July265 290 305 92 330 360
May-July235 260 275 92 300 330
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July46 49 55 77 61 71
May-July35 38 44 90 50 60
Yampa
Maybell, Nr April-July595 655 730 79 795 895
May-July500 560 635 84 700 800
Little Snake
Slater, Nr April-July98 109 125 81 138 153
May-July85 96 112 82 125 140
Dixon, Nr April-July174 199 230 70 250 285
May-July140 165 195 70 215 250
Lily, Nr April-July180 205 235 72 260 295
May-July145 170 200 74 225 260
Yampa
Deerlodge Park April-July775 855 955 80 1040 1170
May-July650 730 830 85 915 1050
White
Meeker, Nr April-July155 168 185 71 205 245
May-July130 143 160 71 180 220
Watson, Nr April-July151 163 181 67 200 240
May-July125 137 155 66 175 215


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-July9.5 10.7 12 61 14.2 16.7
May-July7.8 9 10.3 61 12.5 15
Ashley Ck
Vernal, Nr April-July19.8 22 25 54 30 39
May-July17 19 22 50 27 36
West Fork Duchesne
Vat Diversion, Blo April-July9.1 10.6 12 71 13.1 14.6
May-July8 9.5 10.9 69 12 13.5
Duchesne
Tabiona, Nr April-July64 68 75 73 89 94
May-July55 59 66 71 80 85
Rock Ck
Upper Stillwater Reservoir April-July46 51 60 83 71 76
May-July40 45 54 78 65 70
South Fork Rock Ck
Docs Div, Blo April-July4.1 4.6 5.2 71 6.1 7.1
May-July3.5 4 4.6 68 5.5 6.5
Rock Ck
Mountain Home, Nr April-July57 62 72 83 80 87
May-July50 55 65 79 73 80
Currant Ck
Currant Ck Reservoir April-July8.6 10 12 68 13.6 15.6
May-July7 8.4 10.4 68 12 14
Strawberry
Strawberry Reservoir, Soldier Springs April-July23 27 30 50 38 43
May-July10 14 17.5 36 25 30
Starvation Reservoir, Duchesne, Nr April-July30 37 45 48 60 68
May-July15 22 30 40 45 53
Duchesne
Duchesne, Nr, Knight Div, Abv April-July120 130 145 77 165 175
May-July105 115 130 75 150 160
Lake Fork
Moon Lake Reservoir, Mtn Home, Nr April-July34 38 45 70 52 64
May-July30 34 41 68 48 60
Yellowstone
Altonah, Nr April-July34 39 45 75 53 59
May-July30 35 41 73 49 55
Whiterocks
Whiterocks, Nr April-July25 28 35 69 43 53
May-July22 25 32 67 40 50
Uinta
Neola, Nr April-July35 41 50 69 58 73
May-July32 38 47 68 55 70
Duchesne
Myton April-July130 145 175 57 215 255
May-July100 115 145 54 185 225
Randlett, Nr April-July140 155 185 53 225 270
May-July110 125 155 50 195 240


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-July5 5.5 6.5 52 8 9.5
May-July3 3.5 4.5 47 6 7.5
Fish Ck
Scofield, Nr, Reservoir, Abv April-July14.7 17.2 19 73 23 25
May-July12 14.5 16.3 74 20 22
Price
Scofield Reservoir, Scofield, Nr April-July18.8 21 24 71 30 32
May-July14 16.5 19.2 66 25 27
Green
Green River, Ut April-July1440 1640 1800 64 2110 2340
May-July1200 1400 1560 64 1870 2100
Huntington Ck
Electric Lake April-July5.7 6.5 7.5 66 9.2 10.7
May-July5 5.8 6.8 68 8.5 10
Power Plant, Blo April-July22 27 30 75 36 39
May-July20 25 28 76 34 37
Seeley Ck
Joes Vly Reservoir, Orangeville, Nr April-July28 31 36 71 40 43
May-July25 28 33 70 37 40
Ferron Ck
Ferron, Nr April-July16.9 18.9 22 63 25 28
May-July15 17 20 61 23 26
Muddy Ck
Emery, Nr April-July6.8 8.3 9 49 10.8 11.8
May-July6 7.5 8.2 49 10 11


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-July155 170 185 82 205 230
May-July139 154 169 80 190 215
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July36 42 48 96 54 60
May-July21 27 33 73 39 45
Fraser
Winter Park April-July12 13.3 14.5 78 16 18
May-July11 12.3 13.5 76 15 17
Williams Fork
Williams Fork Reservoir, Parshall April-July54 62 68 71 75 83
May-July46 54 60 67 67 75
Muddy Ck
Wolford Mountain Reservoir April-July20 25 29 56 35 42
May-July16 21 25 57 31 38
Blue
Dillon Reservoir April-July105 117 128 77 140 155
May-July97 109 120 77 132 147
Green Mtn Reservoir April-July180 200 220 79 240 265
May-July162 182 200 77 220 245
Colorado
Kremmling, Nr April-July550 620 680 78 740 820
May-July465 535 595 75 655 735
Eagle
Gypsum, Blo April-July200 225 245 73 275 300
May-July185 210 230 73 260 285
Colorado
Dotsero, Nr April-July880 995 1080 77 1170 1280
May-July755 870 955 75 1040 1150
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July90 100 110 81 120 135
May-July82 92 102 81 112 127
Roaring Fork
Glenwood Springs April-July460 510 550 84 590 640
May-July410 460 500 83 540 590
Colorado
Glenwood Springs, Blo April-July1400 1550 1680 81 1800 1940
May-July1220 1370 1500 79 1620 1760
Cameo, Nr April-July1500 1660 1800 79 1950 2100
May-July1310 1470 1610 78 1760 1910
Cisco, Nr April-July2400 2700 2980 73 3300 3600
May-July1980 2280 2560 72 2880 3180
Lake Powell, Glen Cyn Dam, At April-July2790 3290 3800 59 4330 5090
May-July2200 2700 3210 58 3740 4500


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-July79 85 90 96 96 107
May-July71 77 82 96 88 99
Almont April-July114 126 136 93 142 156
May-July103 115 125 95 131 145
East
Almont April-July140 154 164 93 174 191
May-July124 138 148 92 158 175
Gunnison
Gunnison, Nr April-July265 290 315 90 335 360
May-July235 260 285 90 305 330
Tomichi Ck
Gunnison April-July31 36 40 60 45 59
May-July22 27 31 56 36 50
Lake Fork
Gateview April-July60 69 78 66 86 100
May-July54 63 72 65 80 94
Gunnison
Blue Mesa Reservoir April-July405 450 490 77 520 590
May-July345 390 430 77 460 530
Morrow Point Reservoir April-July430 475 515 75 545 620
May-July365 410 450 75 480 555
Crystal Reservoir April-July465 520 560 73 600 685
May-July390 445 485 72 525 610
Muddy Ck
Paonia Reservoir, Bardine, Nr April-July50 56 61 75 68 79
May-July35 41 46 74 53 64
Nf Gunnison
Somerset, Nr April-July187 200 220 83 235 260
May-July139 154 170 79 185 210
Surface Ck
Cedaredge April-July10.6 12.2 13.5 92 14.9 16.9
May-July7.5 9.1 10.4 86 11.8 13.8
Uncompahgre
Ridgway Reservoir April-July50 57 62 67 67 77
May-July43 50 55 66 60 70
Colona April-July51 62 70 58 77 96
May-July43 54 62 58 69 88
Delta April-July25 37 47 49 62 77
May-July18 30 40 49 55 70
Gunnison
Grand Junction, Nr April-July780 855 950 71 1020 1170
May-July610 685 780 70 850 1000


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-July100 113 130 60 148 169
May-July65 78 95 54 113 134
Mcphee Reservoir April-July110 122 136 53 156 176
May-July69 81 95 49 115 135
San Miguel
Placerville, Nr April-July49 55 61 53 68 78
May-July41 47 53 52 60 70
Dolores
Cisco, Nr April-July156 183 220 44 255 290
May-July85 112 150 39 182 220


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-July115 126 140 72 149 171
May-July74 85 99 62 108 130
Carracas, Nr April-July186 205 225 68 240 275
May-July120 138 159 61 175 210
Navajo Reservoir, Archuleta, Nr April-July310 340 380 60 410 480
May-July185 215 255 53 285 355
Bluff, Nr April-July555 590 625 56 680 785
May-July370 405 440 50 495 600
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July30 32 34 69 37 43
May-July20 22 24 60 27 33
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July33 36 39 67 42 48
May-July24 27 30 63 33 39
Little Navajo
Oso Div Dam,bl,chromo,nr April-July2.6 2.9 3.4 56 3.9 4.4
May-July1.2 1.5 2 45 2.5 3
Piedra
Arboles, Nr April-July90 98 106 59 114 130
May-July56 64 72 55 80 96
Los Pinos
Vallecito Reservoir, Bayfield, Nr April-July103 112 121 68 133 149
May-July76 85 94 61 106 122
Animas
Durango April-July205 230 260 68 285 325
May-July168 193 225 67 250 290
Florida
Lemon Reservoir, Durango, Nr April-July24 27 30 63 34 39
May-July19 22 25 60 29 34
La Plata
Hesperus April-July11.5 12.4 13.1 57 14.8 17.6
May-July7.9 8.8 9.5 52 11.2 14
Mancos
Mancos, Nr April-July7.5 9.3 11 64 12.5 15
May-July3.5 5.3 7 58 8.5 11

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 152.0 112 46 125.2 92 136.2 334.0
untitled Big Sandy
Big Sandy Reservoir, Nr Farson 10.5 47 27 11.5 51 22.4 38.3
Blacks Fork
Meeks Cabin 16.6 96 56 8.4 49 17.3 29.9
untitled Ef Smiths Fork
Stateline Reservoir, Robertson,nr 7.2 110 52 4.5 69 6.5 13.9
untitled Green
Flaming Gorge Reservoir 2937.8 95 78 3178.3 103 3087.2 3749.0
untitled Strawberry
Strawberry Reservoir, Soldier Springs 855.2 103 77 926.2 112 828.0 1105.9
Starvation Reservoir, Duchesne, Nr 156.1 102 94 164.9 107 153.6 165.3
untitled Rock Ck
Upper Stillwater Reservoir 2.5 85 8 4.0 134 3.0 31.4
untitled Lake Fork
Moon Lake Reservoir, Mtn Home, Nr 27.2 119 74 16.0 70 22.9 36.5
untitled Big Brush Ck
Red Fleet Reservoir, Vernal, Nr 12.5 64 49 16.7 86 19.4 25.7
untitled Price
Scofield Reservoir, Scofield, Nr 25.4 85 39 36.8 123 29.9 65.8
untitled Seeley Ck
Joes Vly Reservoir, Orangeville, Nr 23.2 60 37 37.4 97 38.5 62.5
untitled Huntington Ck
Electric Lake 10.8 61 34 18.4 105 17.6 31.5
untitled
TOTAL 4237.0 97 74 4548.3 104 4382.6 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 331.4 101 68 350.2 107 326.9 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 8.5 109 94 7.2 93 7.8 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 63.2 94 65 61.0 91 67.1 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 32.2 66 49 52.8 108 48.8 66.0
untitled Blue
Dillon Reservoir 197.4 93 78 202.8 95 213.3 254.0
Green Mtn Reservoir 52.7 79 36 54.5 82 66.6 146.9
untitled Homestake Ck
Homestake Reservoir 5.3 30 12 12.1 68 17.9 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 59.3 93 58 59.6 93 63.7 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 10.0 54 30 8.3 45 18.3 32.9
untitled Taylor
Taylor Park Reservoir 59.3 88 56 63.6 94 67.6 106.2
untitled Gunnison
Blue Mesa Reservoir 252.3 51 30 365.2 74 496.4 827.9
Morrow Point Reservoir 111.7 101 95 102.6 93 110.3 117.0
Crystal Reservoir 16.8 102 96 16.9 102 16.5 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 7.8 126 46 10.3 168 6.1 16.7
untitled Uncompahgre
Ridgway Reservoir 61.5 94 74 57.8 88 65.5 83.0
untitled Dolores
Mcphee Reservoir 213.3 70 56 176.4 58 305.0 381.1
untitled
TOTAL 1482.6 78 53 1601.2 84 1898.0 2790.6
Colorado
Lake Powell 5790.6 41 24 8504.5 60 14105.3 24322.0
untitled
TOTAL 5790.6 41 24 8504.5 60 14105.3 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 73.0 92 58 56.6 72 79.1 125.4
untitled San Juan
Navajo Reservoir, Archuleta, Nr 898.3 67 53 1044.6 77 1350.6 1696.0
untitled Florida
Lemon Reservoir, Durango, Nr 19.0 84 48 13.2 59 22.6 39.8
untitled
TOTAL 990.3 68 53 1114.4 77 1452.2 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