Lake Powell Water Supply Outlook, February 1, 2019

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-July126 162 190 78 215 285
Pine Ck
Fremont Lk, Abv April-July60 70 82 84 87 104
New Fork
Big Piney, Nr April-July150 200 250 70 300 380
Green
Fontenelle Res, Fontenelle Nr April-July290 410 500 69 600 845
Big Sandy
Farson, Nr April-July25 36 41 79 48 64
Green
Green River, Wy, Nr April-July290 420 505 69 610 850
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July23 28 34 63 41 59
Viva Naughton Res April-July29 35 44 59 56 92
Blacks Fork
Robertson, Nr April-July49 62 75 84 91 120
Ef Smiths Fork
Stateline Res, Robertson,nr April-July17.2 20 23 88 28 32
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July360 525 630 64 760 1230


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 17.5 19.5 85 21 31
Steamboat Springs April-July160 205 235 90 265 330
Elk
Milner, Nr April-July210 265 310 97 345 405
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July33 46 55 75 64 77
Yampa
Maybell, Nr April-July580 705 850 91 945 1170
Little Snake
Slater, Nr April-July82 114 135 87 154 185
Dixon, Nr April-July160 220 270 78 345 430
Lily, Nr April-July157 230 280 81 375 455
Yampa
Deerlodge Park April-July720 920 1130 91 1260 1550
White
Meeker, Nr April-July178 200 235 84 260 320
Watson, Nr April-July186 210 250 89 275 360


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-July10.1 13.6 16 76 19 27
Ashley Ck
Vernal, Nr April-July22 30 40 80 45 66
West Fork Duchesne
Vat Diversion, Blo April-July13 17.3 20 108 23 30
Duchesne
Tabiona, Nr April-July71 88 100 93 110 134
Rock Ck
Upper Stillwater Res April-July55 65 77 104 90 115
South Fork Rock Ck
Docs Div, Blo April-July5.1 6.4 7.5 103 9 10.5
Rock Ck
Mountain Home, Nr April-July65 76 91 103 107 136
Currant Ck
Currant Ck Res April-July14 19.2 23 115 26 36
Strawberry
Solider Springs,nr April-July38 55 68 96 89 108
Starvation Res, Duchesne, Nr April-July75 100 120 107 150 200
Duchesne
Duchesne, Nr, Knight Div, Abv April-July134 163 189 97 215 265
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July45 58 64 97 76 98
Yellowstone
Altonah, Nr April-July38 52 60 98 68 85
Whiterocks
Whiterocks, Nr April-July25 35 43 80 48 71
Uinta
Neola, Nr April-July40 63 73 99 81 108
Duchesne
Myton April-July194 260 320 97 395 525
Randlett, Nr April-July205 270 335 87 420 605


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-July8.5 13.7 16.8 108 22 27
Fish Ck
Scofield, Nr, Reservoir, Abv April-July22 25 31 103 38 49
Price
Scofield Res, Scofield, Nr April-July31 35 41 100 52 68
Green
Green River, Ut April-July1730 2030 2400 81 2840 4000
Huntington Ck
Electric Lake April-July10.1 11.4 14 105 17.8 24
Power Plant, Blo April-July30 37 44 110 55 72
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July39 51 57 102 64 88
Ferron Ck
Ferron, Nr April-July27 35 40 105 45 60
Muddy Ck
Emery, Nr April-July10.8 14.2 16.5 83 19.7 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-July145 183 210 95 255 315
Willow Ck
Willow Ck Res, Granby, Nr April-July26 35 45 96 58 76
Fraser
Winter Park April-July13 15.5 18.3 94 21 24
Williams Fork
Williams Fork Res, Parshall, Nr April-July60 72 84 88 100 120
Muddy Ck
Wolford Mountain Reservoir April-July29 42 53 98 64 76
Blue
Dillon Res April-July108 130 155 95 175 205
Green Mtn Res April-July180 215 255 93 290 350
Colorado
Kremmling, Nr April-July530 650 780 91 920 1140
Eagle
Gypsum, Blo April-July210 250 295 88 345 430
Colorado
Dotsero, Nr April-July880 1060 1270 91 1500 1860
Frying Pan
Ruedi Res, Basalt, Nr April-July80 100 120 86 140 165
Roaring Fork
Glenwood Springs April-July430 510 590 86 680 810
Colorado
Glenwood Springs, Blo April-July1340 1650 1900 90 2200 2740
Cameo, Nr April-July1500 1800 2100 89 2450 3050
Plateau Ck
Cameo, Nr April-July70 90 110 89 130 160
Colorado
Cisco, Nr April-July2700 3200 3700 83 4200 5200
Lake Powell, Glen Cyn Dam, At April-July3600 4480 5300 74 6050 8800


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-July58 75 81 82 95 115
Almont April-July90 110 124 80 145 175
East
Almont April-July115 140 162 89 180 220
Gunnison
Gunnison, Nr April-July225 275 310 84 350 435
Tomichi Ck
Gunnison April-July30 45 55 74 70 100
Lake Fork
Gateview April-July70 91 110 89 120 160
Gunnison
Blue Mesa Res April-July390 490 550 81 600 800
Morrow Point Res April-July430 530 590 80 640 840
Crystal Res April-July500 600 660 79 710 910
Muddy Ck
Paonia Res, Bardine, Nr March-June54 65 71 74 82 120
April-July55 66 72 74 83 121
Nf Gunnison
Somerset, Nr April-July190 225 245 83 275 370
Surface Ck
Cedaredge April-July11 13 16 95 17.5 22
Uncompahgre
Ridgway Res April-July57 75 81 80 88 117
Colona April-July70 98 105 77 120 165
Delta April-July41 65 79 70 87 145
Gunnison
Grand Junction, Nr April-July880 1000 1200 81 1300 1790


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-July130 165 200 82 235 310
Mcphee Res April-July138 185 230 78 260 365
San Miguel
Placerville, Nr April-July60 80 95 74 105 140
Dolores
Cisco, Nr April-July230 335 400 71 455 630


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-July95 115 135 63 160 230
Carracas, Nr April-July170 200 240 63 295 400
Navajo Res, Archuleta, Nr April-July275 350 430 59 505 750
Farmington April-July415 530 640 58 745 1080
Bluff, Nr April-July400 510 640 58 750 1050
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July27 31 38 70 45 60
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July31 36 45 69 56 70
Piedra
Arboles, Nr April-July80 102 120 57 152 225
Los Pinos
Vallecito Res, Bayfield, Nr April-July92 119 135 70 165 210
Animas
Durango April-July200 265 290 70 355 425
Florida
Lemon Res, Durango, Nr April-July22 29 35 64 44 58
La Plata
Hesperus April-July10 13.5 16.5 72 21 25
Mancos
Mancos, Nr April-July10 14 17 55 23 33

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 391.1 111 80 491.4 140 352.2 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.2 104 91 7.8 98 8.0 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 67.3 105 69 66.0 103 63.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 34.2 77 52 54.5 122 44.6 66.0
untitled Blue
Dillon Res 180.7 81 71 240.1 108 223.2 254.0
Green Mtn Res 55.1 68 37 70.5 87 81.1 146.9
untitled Homestake Ck
Homestake Res 41.3 129 96 41.0 128 31.9 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 58.2 80 57 69.4 96 72.4 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 10.9 86 33 10.9 86 12.6 32.9
untitled Taylor
Taylor Park Res 59.2 89 56 74.2 111 66.9 106.2
untitled Gunnison
Blue Mesa Res 251.7 49 30 554.5 108 514.6 829.5
Morrow Point Res 106.8 96 91 109.6 98 111.4 117.0
Crystal Res 15.1 99 86 15.5 101 15.3 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 3.5 82 21 2.9 68 4.2 16.7
untitled Uncompahgre
Ridgway Res 46.4 67 56 60.9 88 69.2 83.0
untitled Dolores
Mcphee Res 168.6 62 44 284.5 105 270.9 381.1
untitled
TOTAL 1498.1 77 54 2153.7 111 1942.5 2792.1
Colorado
Lake Powell 9629.2 56 40 13672.3 79 17338.2 24322.0
untitled
TOTAL 9629.2 56 40 13672.3 79 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 Res, Bayfield, Nr 37.2 59 30 67.3 106 63.5 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 869.1 66 51 1254.9 96 1310.4 1696.0
untitled Florida
Lemon Res, Durango, Nr 6.9 33 17 18.6 89 20.9 39.8
untitled
TOTAL 913.2 65 49 1340.8 96 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