Lake Powell Water Supply Outlook, February 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-July150 180 215 88 250 305
Pine Ck
Fremont Lk, Abv April-July65 75 88 90 95 110
New Fork
Big Piney, Nr April-July175 225 290 82 345 425
Green
Fontenelle Reservoir, Fontenelle, Nr April-July385 500 620 86 730 970
Big Sandy
Farson, Nr April-July23 33 38 73 45 60
Green
Green River, Wy, Nr April-July380 500 625 86 745 980
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July26 32 45 83 55 75
Viva Naughton Reservoir April-July34 43 60 81 75 110
Blacks Fork
Robertson, Nr April-July60 70 85 96 100 130
Ef Smiths Fork
Stateline Reservoir, Robertson,nr April-July20 24 28 108 33 38
Green
Flaming Gorge Reservoir April-July520 670 870 89 1050 1500


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-July16 18 21 91 25 32
Steamboat Springs April-July165 205 250 96 295 340
Elk
Milner, Nr April-July245 295 345 108 380 440
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July43 58 73 100 85 100
Yampa
Maybell, Nr April-July635 765 935 100 1090 1300
Little Snake
Slater, Nr April-July100 130 160 103 180 210
Dixon, Nr April-July200 260 340 99 400 500
Lily, Nr April-July200 265 350 101 440 520
Yampa
Deerlodge Park April-July820 1050 1260 102 1450 1700
White
Meeker, Nr April-July195 215 255 91 285 340
Watson, Nr April-July205 230 265 95 295 380


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-July13 17 20 95 23 31
Ashley Ck
Vernal, Nr April-July28 35 46 92 52 69
West Fork Duchesne
Vat Diversion, Blo April-July10 13 16 86 19 26
Duchesne
Tabiona, Nr April-July71 86 100 93 108 136
Rock Ck
Upper Stillwater Reservoir April-July53 61 71 96 82 110
South Fork Rock Ck
Docs Div, Blo April-July4.5 5.5 6.5 89 8 9.5
Rock Ck
Mountain Home, Nr April-July64 72 84 95 98 133
Currant Ck
Currant Ck Reservoir April-July12 15 18 90 21 29
Strawberry
Strawberry Reservoir, Soldier Springs April-July25 35 50 70 65 90
Starvation Reservoir, Duchesne, Nr April-July60 83 95 85 114 165
Duchesne
Duchesne, Nr, Knight Div, Abv April-July135 162 182 94 205 265
Lake Fork
Moon Lake Reservoir, Mtn Home, Nr April-July42 52 60 91 68 90
Yellowstone
Altonah, Nr April-July42 55 62 102 70 87
Whiterocks
Whiterocks, Nr April-July31 41 50 93 55 77
Uinta
Neola, Nr April-July43 64 75 101 83 110
Duchesne
Myton April-July177 230 270 82 330 490
Randlett, Nr April-July190 245 290 75 360 570


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-July6.2 9.7 14 90 18.8 24
Fish Ck
Scofield, Nr, Reservoir, Abv April-July18 22 26 87 33 43
Price
Scofield Reservoir, Scofield, Nr April-July24 29 35 85 45 59
Green
Green River, Ut April-July1950 2350 2700 91 3200 4400
Huntington Ck
Electric Lake April-July6 9 12 90 15.7 19.5
Power Plant, Blo April-July24 32 40 100 49 63
Seeley Ck
Joes Vly Reservoir, Orangeville, Nr April-July36 44 53 95 67 83
Ferron Ck
Ferron, Nr April-July23 30 38 100 46 58
Muddy Ck
Emery, Nr April-July9 12.7 16 80 21 28


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-July140 172 200 91 245 305
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July20 29 38 81 53 72
Fraser
Winter Park April-July14 16.5 19.4 100 22 25
Williams Fork
Williams Fork Reservoir, Parshall April-July62 77 88 92 108 127
Muddy Ck
Wolford Mountain Reservoir April-July32 44 56 104 68 80
Blue
Dillon Reservoir April-July115 142 160 98 185 210
Green Mtn Reservoir April-July185 230 265 96 310 360
Colorado
Kremmling, Nr April-July540 670 800 93 990 1200
Eagle
Gypsum, Blo April-July210 255 290 87 355 430
Colorado
Dotsero, Nr April-July870 1090 1270 91 1580 1880
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July90 110 130 94 150 180
Roaring Fork
Glenwood Springs April-July465 540 615 89 720 855
Colorado
Glenwood Springs, Blo April-July1360 1670 1950 92 2300 2800
Cameo, Nr April-July1500 1820 2130 90 2600 3100
Plateau Ck
Cameo, Nr April-July60 75 90 73 118 150
Colorado
Cisco, Nr April-July2800 3250 3650 82 4400 5300
Lake Powell, Glen Cyn Dam, At April-July3950 5000 5700 80 6550 9330


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 82 85 86 95 115
Almont April-July103 126 133 86 146 176
East
Almont April-July93 119 138 76 149 194
Gunnison
Gunnison, Nr April-July205 260 290 78 325 415
Tomichi Ck
Gunnison April-July38 53 65 88 79 112
Lake Fork
Gateview April-July76 94 111 90 123 162
Gunnison
Blue Mesa Reservoir April-July395 505 560 83 610 820
Morrow Point Reservoir April-July440 560 610 82 665 890
Crystal Reservoir April-July500 630 685 82 745 1000
Muddy Ck
Paonia Reservoir, Bardine, Nr March-June48 59 65 68 76 104
April-July50 59 65 67 76 106
Nf Gunnison
Somerset, Nr April-July157 190 210 71 235 320
Surface Ck
Cedaredge April-July7.6 9.6 11 65 12.5 16.8
Uncompahgre
Ridgway Reservoir April-July58 77 84 83 90 121
Colona April-July70 95 106 77 117 165
Delta April-July43 70 80 71 92 144
Gunnison
Grand Junction, Nr April-July880 1080 1200 81 1290 1800


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-July134 171 205 84 235 305
Mcphee Reservoir April-July152 197 235 80 270 370
San Miguel
Placerville, Nr April-July62 90 98 77 112 146
Dolores
Cisco, Nr April-July245 360 420 74 485 655


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-July114 137 158 73 178 235
Carracas, Nr April-July192 225 270 71 315 400
Navajo Reservoir, Archuleta, Nr April-July320 410 500 68 575 815
Farmington April-July495 620 750 68 850 1170
Bluff, Nr April-July475 600 735 67 860 1190
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July28 33 40 74 47 57
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July34 39 48 74 57 71
Little Navajo
Oso Div Dam,bl,chromo,nr April-July3.7 4.5 5.5 72 7.6 11
Piedra
Arboles, Nr April-July104 126 146 70 178 255
Los Pinos
Vallecito Reservoir, Bayfield, Nr April-July101 131 146 75 175 215
Animas
Durango April-July215 280 310 75 360 430
Florida
Lemon Reservoir, Durango, Nr April-July27 35 40 73 49 62
La Plata
Hesperus April-July13 16.7 20 87 25 29
Mancos
Mancos, Nr April-July12 17.5 21 68 28 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 176.6 118 51 149.6 100 150.1 344.8
untitled Big Sandy
Big Sandy Reservoir, Nr Farson 22.5 136 59 15.8 95 16.6 38.3
Blacks Fork
Meeks Cabin 10.1 87 34 5.1 44 11.5 29.9
untitled Ef Smiths Fork
Stateline Reservoir, Robertson,nr 5.8 104 42 3.7 66 5.6 13.9
untitled Green
Flaming Gorge Reservoir 3273.6 107 87 3197.7 105 3050.5 3749.0
untitled Strawberry
Strawberry Reservoir, Soldier Springs 958.7 145 87 845.5 128 659.9 1105.9
Starvation Reservoir, Duchesne, Nr 145.0 104 88 132.5 95 138.8 165.3
untitled Rock Ck
Upper Stillwater Reservoir 20.3 235 65 9.5 109 8.6 31.4
untitled Lake Fork
Moon Lake Reservoir, Mtn Home, Nr 27.9 114 76 12.5 51 24.4 36.5
untitled Big Brush Ck
Red Fleet Reservoir, Vernal, Nr 20.7 114 80 11.9 66 18.0 25.7
untitled Price
Scofield Reservoir, Scofield, Nr 51.5 172 78 25.7 86 29.9 65.8
untitled Seeley Ck
Joes Vly Reservoir, Orangeville, Nr 47.3 121 76 30.8 78 39.3 62.5
untitled Huntington Ck
Electric Lake 23.9 125 76 -9999.0 -99 19.2 31.5
untitled
TOTAL 4784.1 115 84 4440.1 107 4172.4 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 436.3 124 89 391.1 111 352.2 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 8.6 108 94 8.2 104 8.0 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 76.3 119 79 67.3 105 63.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 50.8 114 77 34.2 77 44.6 66.0
untitled Blue
Dillon Reservoir 227.8 102 90 180.7 81 223.2 254.0
Green Mtn Reservoir 71.9 89 49 55.1 68 81.1 146.9
untitled Homestake Ck
Homestake Reservoir 41.2 129 96 41.3 129 31.9 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 73.2 101 72 58.2 80 72.4 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 6.4 51 19 6.4 51 12.6 32.9
untitled Taylor
Taylor Park Reservoir 74.1 111 70 59.2 89 66.9 106.2
untitled Gunnison
Blue Mesa Reservoir 554.0 108 67 251.7 49 514.6 829.5
Morrow Point Reservoir 107.2 96 92 106.8 96 111.4 117.0
Crystal Reservoir 14.8 97 85 15.1 99 15.3 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 3.8 90 23 3.5 82 4.2 16.7
untitled Uncompahgre
Ridgway Reservoir 65.3 94 79 46.4 67 69.2 83.0
untitled Dolores
Mcphee Reservoir 288.3 106 76 168.6 62 270.9 381.1
untitled
TOTAL 2099.9 108 75 1493.6 77 1942.5 2792.1
Colorado
Lake Powell 12280.7 71 50 9629.2 56 17338.2 24322.0
untitled
TOTAL 12280.7 71 50 9629.2 56 17338.2 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 78.2 123 62 37.2 59 63.5 125.4
untitled San Juan
Navajo Reservoir, Archuleta, Nr 1307.8 100 77 869.1 66 1310.4 1696.0
untitled Florida
Lemon Reservoir, Durango, Nr 17.5 84 44 6.9 33 20.9 39.8
untitled
TOTAL 1403.5 101 75 913.2 65 1394.7 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