Lake Powell Water Supply Outlook, February 1, 2018

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by CBRFC
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-July205 240 275 112 300 360
Pine Ck
Fremont Lk, Abv April-July77 88 100 102 104 121
New Fork
Big Piney, Nr April-July250 305 355 100 405 485
Green
Fontenelle Res, Fontenelle Nr April-July530 670 750 103 870 1100
Big Sandy
Farson, Nr April-July34 45 50 96 57 73
Green
Green River, Wy, Nr April-July540 680 750 103 885 1120
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July24 29 36 67 44 64
Viva Naughton Res April-July28 35 45 61 56 90
Blacks Fork
Robertson, Nr April-July49 61 70 79 84 112
Ef Smiths Fork
Stateline Res, Robertson,nr April-July15.7 18.2 21 81 25 31
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July600 780 890 91 1030 1470


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-July9 13 14.5 63 15 18.2
Steamboat Springs April-July101 142 174 67 199 255
Elk
Milner, Nr April-July158 200 245 77 275 330
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July21 32 41 56 48 60
Yampa
Maybell, Nr April-July350 470 595 64 680 860
Little Snake
Slater, Nr April-July58 80 95 61 116 148
Dixon, Nr April-July114 154 180 52 230 305
Lily, Nr April-July99 153 185 54 245 315
Yampa
Deerlodge Park April-July440 610 790 64 900 1150
White
Meeker, Nr April-July115 135 155 55 180 230
Watson, Nr April-July117 138 158 56 186 245


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-July8 11.4 12.9 61 15.7 22
Ashley Ck
Vernal, Nr April-July16.7 21 29 58 33 55
West Fork Duchesne
Vat Diversion, Blo April-July5 7.1 8.5 46 10.2 17.1
Duchesne
Tabiona, Nr April-July51 60 72 67 79 104
Rock Ck
Upper Stillwater Res April-July36 42 50 68 61 83
South Fork Rock Ck
Docs Div, Blo April-July2.1 3.1 3.7 51 5 6
Rock Ck
Mountain Home, Nr April-July42 49 59 67 72 98
Currant Ck
Currant Ck Res April-July4.1 5.8 7.5 38 10.9 18.7
Strawberry
Solider Springs,nr April-July11.3 17.7 23 32 31 47
Starvation Res, Duchesne, Nr April-July25 37 45 40 57 84
Duchesne
Duchesne, Nr, Knight Div, Abv April-July90 109 129 66 147 205
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July29 35 42 64 51 72
Yellowstone
Altonah, Nr April-July28 35 41 67 48 65
Whiterocks
Whiterocks, Nr April-July19.8 27 33 61 38 58
Uinta
Neola, Nr April-July27 41 50 68 58 80
Duchesne
Myton April-July80 113 150 45 197 315
Randlett, Nr April-July88 119 154 40 205 340


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-July1.7 3.6 4.9 32 6.7 9.9
Fish Ck
Scofield, Nr, Reservoir, Abv April-July6.3 8.6 10.7 36 15.5 24
Price
Scofield Res, Scofield, Nr April-July8.5 11.6 14 34 21 32
Green
Green River, Ut April-July1300 1620 1920 65 2290 3270
Huntington Ck
Electric Lake April-July3 3.7 4.3 32 5.3 8.7
Power Plant, Blo April-July15.1 16.4 17.4 44 19 25
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July15.4 21 24 43 30 46
Ferron Ck
Ferron, Nr April-July8.5 13.3 16.2 43 21 32
Muddy Ck
Emery, Nr April-July4.1 6.3 6.7 34 8.2 12.9


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-July124 150 180 82 210 280
Willow Ck
Willow Ck Res, Granby, Nr April-July21 29 40 85 52 70
Fraser
Winter Park April-July12 15 17.5 90 19.5 23
Williams Fork
Williams Fork Res, Parshall, Nr April-July56 70 80 83 90 114
Muddy Ck
Wolford Mountain Reservoir April-July16 24 33 61 42 54
Blue
Dillon Res April-July94 120 140 86 160 188
Green Mtn Res April-July150 195 230 84 260 315
Colorado
Kremmling, Nr April-July455 580 680 79 790 1050
Eagle
Gypsum, Blo April-July146 250 220 66 190 335
Colorado
Dotsero, Nr April-July680 1200 1030 74 880 1550
Frying Pan
Ruedi Res, Basalt, Nr April-July61 105 93 67 80 140
Roaring Fork
Glenwood Springs April-July320 500 450 65 400 670
Colorado
Glenwood Springs, Blo April-July1030 1700 1510 72 1350 2270
Cameo, Nr April-July1110 1800 1620 69 1400 2450
Plateau Ck
Cameo, Nr April-July18 60 45 36 33 90
Colorado
Cisco, Nr April-July1650 2800 2410 54 2000 3800
Lake Powell, Glen Cyn Dam, At April-July1950 2750 3400 47 4200 6200


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 Res April-July45 56 70 71 78 90
Almont April-July65 85 104 67 118 135
East
Almont April-July70 88 109 60 130 160
Gunnison
Gunnison, Nr April-July135 175 225 61 270 320
Tomichi Ck
Gunnison April-July20 28 36 49 50 71
Lake Fork
Gateview April-July45 55 74 60 91 109
Gunnison
Blue Mesa Res April-July230 290 400 59 480 600
Morrow Point Res April-July265 325 435 59 475 635
Crystal Res April-July310 370 480 57 520 680
Muddy Ck
Paonia Res, Bardine, Nr March-June18 24 35 36 48 69
April-July17 23 34 35 47 68
Nf Gunnison
Somerset, Nr April-July85 105 135 46 160 235
Surface Ck
Cedaredge April-July2.5 3 4.5 27 6 9
Uncompahgre
Ridgway Res April-July35 43 56 55 68 87
Colona April-July37 49 62 45 83 110
Delta April-July19 27 35 31 54 80
Gunnison
Grand Junction, Nr April-July500 600 725 49 900 1180


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-July60 83 100 41 140 186
Mcphee Res April-July61 86 110 37 155 200
San Miguel
Placerville, Nr April-July38 52 64 50 77 95
Dolores
Cisco, Nr April-July86 120 155 27 195 270


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-July50 75 100 47 125 160
Carracas, Nr April-July100 130 175 46 215 275
Navajo Res, Archuleta, Nr April-July120 180 260 35 340 500
Farmington April-July215 300 370 34 470 630
Bluff, Nr April-July190 270 340 31 425 610
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July15 22 30 56 36 45
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July19 24 35 54 42 52
Piedra
Arboles, Nr April-July40 52 77 37 95 140
Los Pinos
Vallecito Res, Bayfield, Nr April-July38 55 75 39 95 130
Animas
Durango April-July90 120 165 40 195 250
Florida
Lemon Res, Durango, Nr April-July9 12 18 33 25 35
La Plata
Hesperus April-July3 4.5 7 30 10 13
Mancos
Mancos, Nr April-July5 7 10 32 14 20

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 Res, Fontenelle Nr 165.2 110 48 184.2 123 150.1 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 30.8 186 80 23.5 142 16.6 38.3
Blacks Fork
Meeks Cabin 10.0 87 34 11.2 97 11.5 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 6.0 108 43 6.4 114 5.6 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 3259.2 107 87 3087.3 101 3050.5 3749.0
untitled Strawberry
Solider Springs,nr 930.6 141 84 776.1 118 659.9 1105.9
Starvation Res, Duchesne, Nr 158.6 114 96 142.2 102 138.8 165.3
untitled Rock Ck
Upper Stillwater Res 9.4 109 30 15.1 175 8.6 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 25.2 103 69 24.7 101 24.4 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 19.8 109 77 21.4 118 18.0 25.7
untitled Price
Scofield Res, Scofield, Nr 50.0 167 76 14.5 49 29.9 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 45.3 115 72 30.4 77 39.3 62.5
untitled Huntington Ck
Electric Lake 24.5 128 78 16.1 84 19.2 31.5
untitled
TOTAL 4734.6 113 83 4353.2 104 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 491.4 140 100 424.3 120 352.2 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 7.8 98 86 8.2 104 8.0 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 66.0 103 68 74.4 117 63.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 54.5 122 83 50.7 114 44.6 66.0
untitled Blue
Dillon Res 240.1 108 95 224.0 100 223.2 254.0
Green Mtn Res 70.5 87 48 67.2 83 81.1 146.9
untitled Homestake Ck
Homestake Res -9999.0 -99 -99 42.1 132 31.9 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 69.4 96 68 67.8 94 72.4 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 11.0 87 33 11.9 94 12.6 32.9
untitled Taylor
Taylor Park Res 74.2 111 70 69.5 104 66.9 106.2
untitled Gunnison
Blue Mesa Res 554.5 108 67 586.6 114 514.6 829.5
Morrow Point Res 109.3 98 93 112.0 101 111.4 117.0
Crystal Res 15.5 101 88 16.2 105 15.3 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 2.9 68 17 1.6 38 4.2 16.7
untitled Uncompahgre
Ridgway Res 60.9 88 73 63.8 92 69.2 83.0
untitled Dolores
Mcphee Res 284.5 105 75 294.4 109 270.9 381.1
untitled
TOTAL 2112.6 111 77 2114.7 109 1910.6 2749.1


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 Res, Bayfield, Nr 67.3 106 54 84.3 133 63.5 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 1254.9 96 74 1305.8 100 1310.4 1696.0
untitled Florida
Lemon Res, Durango, Nr 18.6 89 47 20.6 99 20.9 39.8
untitled
TOTAL 1340.8 96 72 1410.7 101 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