Lake Powell Water Supply Outlook, March 1, 2020

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-July170 195 220 90 245 280
Pine Ck
Fremont Lk, Abv April-July63 72 88 90 93 103
New Fork
Big Piney, Nr April-July170 215 270 76 320 380
Green
Fontenelle Reservoir, Fontenelle, Nr April-July420 525 620 86 720 880
Big Sandy
Farson, Nr April-July20 27 32 62 38 52
Green
Green River, Wy, Nr April-July415 535 620 85 725 900
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July29 35 45 83 55 70
Viva Naughton Reservoir April-July38 47 60 81 76 102
Blacks Fork
Robertson, Nr April-July60 70 85 96 98 120
Ef Smiths Fork
Stateline Reservoir, Robertson,nr April-July21 25 28 108 31 36
Green
Flaming Gorge Reservoir April-July550 660 850 87 1050 1350


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-July18 20 23 100 26 40
Steamboat Springs April-July200 240 270 104 315 370
Elk
Milner, Nr April-July290 335 365 114 405 465
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July55 68 80 110 90 114
Yampa
Maybell, Nr April-July740 890 1010 108 1150 1390
Little Snake
Slater, Nr April-July120 150 170 109 187 230
Dixon, Nr April-July235 305 360 104 400 525
Lily, Nr April-July235 310 380 110 420 550
Yampa
Deerlodge Park April-July975 1200 1380 111 1540 1900
White
Meeker, Nr April-July195 230 250 89 275 365
Watson, Nr April-July205 240 260 93 295 395


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 15 18 86 21 27
Ashley Ck
Vernal, Nr April-July24 30 42 84 48 62
West Fork Duchesne
Vat Diversion, Blo April-July9.5 11.5 15 81 17 20
Duchesne
Tabiona, Nr April-July70 80 92 85 105 115
Rock Ck
Upper Stillwater Reservoir April-July48 55 67 91 75 85
South Fork Rock Ck
Docs Div, Blo April-July3.5 4.7 6 82 7 8
Rock Ck
Mountain Home, Nr April-July58 68 80 91 91 102
Currant Ck
Currant Ck Reservoir April-July11 14 16 80 19 22
Strawberry
Strawberry Reservoir, Soldier Springs April-July25 31 45 63 55 75
Starvation Reservoir, Duchesne, Nr April-July65 74 90 80 105 130
Duchesne
Duchesne, Nr, Knight Div, Abv April-July130 150 170 88 193 210
Lake Fork
Moon Lake Reservoir, Mtn Home, Nr April-July35 47 55 83 62 72
Yellowstone
Altonah, Nr April-July39 53 59 97 66 78
Whiterocks
Whiterocks, Nr April-July28 34 45 83 52 65
Uinta
Neola, Nr April-July40 55 65 88 76 91
Duchesne
Myton April-July155 215 255 77 310 365
Randlett, Nr April-July170 225 280 73 335 430


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-July5.7 8.1 10 65 13.7 18.7
Fish Ck
Scofield, Nr, Reservoir, Abv April-July18 21 25 83 30 37
Price
Scofield Reservoir, Scofield, Nr April-July23 28 34 83 40 50
Green
Green River, Ut April-July2000 2400 2670 90 3450 3900
Huntington Ck
Electric Lake April-July6 7.3 9.7 73 11.8 16.3
Power Plant, Blo April-July25 30 37 93 44 57
Seeley Ck
Joes Vly Reservoir, Orangeville, Nr April-July37 43 51 91 59 73
Ferron Ck
Ferron, Nr April-July23 30 36 95 42 51
Muddy Ck
Emery, Nr April-July9.7 11.7 13.7 69 17.3 22


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-July165 195 230 105 265 315
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July30 39 48 102 61 78
Fraser
Winter Park April-July16 18.5 21 108 23 26
Williams Fork
Williams Fork Reservoir, Parshall April-July70 84 97 101 110 130
Muddy Ck
Wolford Mountain Reservoir April-July49 61 72 133 84 96
Blue
Dillon Reservoir April-July140 163 185 113 205 225
Green Mtn Reservoir April-July215 265 300 109 335 370
Colorado
Kremmling, Nr April-July700 815 930 108 1100 1270
Eagle
Gypsum, Blo April-July250 290 330 99 385 455
Colorado
Dotsero, Nr April-July1100 1280 1460 104 1740 2030
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July105 120 140 101 155 190
Roaring Fork
Glenwood Springs April-July490 565 640 93 735 835
Colorado
Glenwood Springs, Blo April-July1620 1860 2100 100 2500 2900
Cameo, Nr April-July1750 2000 2250 95 2700 3180
Plateau Ck
Cameo, Nr April-July40 55 70 56 95 120
Colorado
Cisco, Nr April-July2700 3120 3550 80 4200 5180
Lake Powell, Glen Cyn Dam, At April-July4050 4840 5700 80 6370 9050


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-July68 75 82 83 88 108
Almont April-July103 115 126 81 135 166
East
Almont April-July93 117 130 71 139 183
Gunnison
Gunnison, Nr April-July205 245 275 74 290 385
Tomichi Ck
Gunnison April-July36 51 62 84 70 100
Lake Fork
Gateview April-July65 89 101 82 113 147
Gunnison
Blue Mesa Reservoir April-July410 470 525 78 585 755
Morrow Point Reservoir April-July445 520 570 77 640 830
Crystal Reservoir April-July500 590 640 77 720 955
Muddy Ck
Paonia Reservoir, Bardine, Nr March-June41 54 60 63 71 95
April-July41 55 60 62 72 96
Nf Gunnison
Somerset, Nr April-July150 171 200 68 220 310
Surface Ck
Cedaredge April-July5.6 7.3 9 54 10.8 13.7
Uncompahgre
Ridgway Reservoir April-July54 74 80 79 86 116
Colona April-July63 92 99 72 112 157
Delta April-July36 64 73 65 83 131
Gunnison
Grand Junction, Nr April-July785 975 1070 72 1180 1700


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-July97 141 165 67 193 265
Mcphee Reservoir April-July108 162 190 64 220 310
San Miguel
Placerville, Nr April-July55 76 87 68 95 135
Dolores
Cisco, Nr April-July179 280 320 57 380 520


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-July84 110 132 61 145 198
Carracas, Nr April-July147 189 230 61 250 340
Navajo Reservoir, Archuleta, Nr April-July240 345 440 60 515 725
Farmington April-July385 530 660 60 740 1030
Bluff, Nr April-July345 520 640 58 725 1040
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July23 29 35 65 39 48
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July26 33 40 62 44 56
Little Navajo
Oso Div Dam,bl,chromo,nr April-July2.6 3.4 4.6 61 5.7 7.9
Piedra
Arboles, Nr April-July76 104 125 60 151 210
Los Pinos
Vallecito Reservoir, Bayfield, Nr April-July87 118 140 72 154 199
Animas
Durango April-July178 250 290 70 320 395
Florida
Lemon Reservoir, Durango, Nr April-July23 31 38 69 44 57
La Plata
Hesperus April-July9.6 11.9 16.4 71 18 24
Mancos
Mancos, Nr April-July9.7 14 18 58 23 30

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 147.3 115 43 120.1 94 127.6 344.8
untitled Big Sandy
Big Sandy Reservoir, Nr Farson 23.1 153 60 16.5 109 15.1 38.3
Blacks Fork
Meeks Cabin 11.0 89 37 5.9 48 12.3 29.9
untitled Ef Smiths Fork
Stateline Reservoir, Robertson,nr 5.7 107 41 3.9 73 5.4 13.9
untitled Green
Flaming Gorge Reservoir 3225.3 107 86 3148.8 104 3015.6 3749.0
untitled Strawberry
Strawberry Reservoir, Soldier Springs 961.3 146 87 849.6 129 660.2 1105.9
Starvation Reservoir, Duchesne, Nr 153.5 106 93 140.8 97 144.5 165.3
untitled Rock Ck
Upper Stillwater Reservoir 20.1 262 64 9.6 125 7.6 31.4
untitled Lake Fork
Moon Lake Reservoir, Mtn Home, Nr 28.9 109 79 13.9 52 26.6 36.5
untitled Big Brush Ck
Red Fleet Reservoir, Vernal, Nr 21.1 114 82 12.4 67 18.5 25.7
untitled Price
Scofield Reservoir, Scofield, Nr 51.7 169 79 27.1 89 30.6 65.8
untitled Seeley Ck
Joes Vly Reservoir, Orangeville, Nr 47.8 119 77 30.9 77 40.2 62.5
untitled Huntington Ck
Electric Lake 23.4 124 74 -9999.0 -99 18.8 31.5
untitled
TOTAL 4720.2 114 83 4379.4 107 4123.0 5700.4


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 416.3 125 85 363.3 109 332.0 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 8.9 108 98 8.5 103 8.2 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 75.1 120 78 65.5 105 62.4 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 50.6 114 77 33.7 76 44.2 66.0
untitled Blue
Dillon Reservoir 228.2 104 90 179.1 82 219.3 254.0
Green Mtn Reservoir 70.3 96 48 52.7 72 73.5 146.9
untitled Homestake Ck
Homestake Reservoir 41.3 134 96 33.6 109 30.7 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 70.9 104 69 56.5 83 67.9 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 15.3 116 47 6.9 52 13.2 32.9
untitled Taylor
Taylor Park Reservoir 72.8 111 69 59.6 91 65.7 106.2
untitled Gunnison
Blue Mesa Reservoir 537.0 111 65 247.7 51 482.2 829.5
Morrow Point Reservoir 107.4 97 92 107.2 96 111.1 117.0
Crystal Reservoir 15.7 100 90 15.6 99 15.8 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 5.0 108 30 4.1 89 4.7 16.7
untitled Uncompahgre
Ridgway Reservoir 66.0 95 79 46.9 68 69.4 83.0
untitled Dolores
Mcphee Reservoir 286.7 105 75 167.3 61 272.3 381.1
untitled
TOTAL 2067.6 110 74 1448.2 77 1872.6 2792.1
Colorado
Lake Powell 12011.5 70 49 9260.7 54 17054.6 24322.0
untitled
TOTAL 12011.5 70 49 9260.7 54 17054.6 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 79.9 126 64 40.7 64 63.5 125.4
untitled San Juan
Navajo Reservoir, Archuleta, Nr 1294.8 100 76 865.2 67 1292.2 1696.0
untitled Florida
Lemon Reservoir, Durango, Nr 17.4 83 44 7.0 34 21.0 39.8
untitled
TOTAL 1392.1 101 75 913.0 66 1376.7 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 1981-2010 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