Lake Powell Water Supply Outlook, January 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-July127 160 190 78 225 285
Pine Ck
Fremont Lk, Abv April-July57 70 82 84 90 108
New Fork
Big Piney, Nr April-July142 215 250 70 310 420
Green
Fontenelle Res, Fontenelle Nr April-July225 390 500 69 665 860
Big Sandy
Farson, Nr April-July21 32 37 71 43 60
Green
Green River, Wy, Nr April-July225 410 505 69 650 870
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July21 25 34 63 49 65
Viva Naughton Res April-July26 33 44 59 71 93
Blacks Fork
Robertson, Nr April-July40 61 72 81 84 107
Ef Smiths Fork
Stateline Res, Robertson,nr April-July13.7 17.5 21 81 24 31
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July300 455 630 64 845 1220


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-July14 16.2 18.5 80 20 26
Steamboat Springs April-July125 169 220 85 260 325
Elk
Milner, Nr April-July172 220 290 91 340 375
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July20 36 55 75 65 81
Yampa
Maybell, Nr April-July405 560 790 84 890 1120
Little Snake
Slater, Nr April-July60 82 125 80 149 178
Dixon, Nr April-July113 165 250 72 310 420
Lily, Nr April-July106 164 260 75 320 465
Yampa
Deerlodge Park April-July500 715 1050 85 1230 1500
White
Meeker, Nr April-July140 172 225 80 245 295
Watson, Nr April-July142 180 235 84 265 315


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-July7.5 10.8 12.5 60 15.1 21
Ashley Ck
Vernal, Nr April-July18.1 26 30 60 36 55
West Fork Duchesne
Vat Diversion, Blo April-July8.7 12.1 14 75 21 25
Duchesne
Tabiona, Nr April-July51 68 85 79 103 120
Rock Ck
Upper Stillwater Res April-July40 50 61 82 76 97
South Fork Rock Ck
Docs Div, Blo April-July3.1 4.3 5.5 75 6.9 9.9
Rock Ck
Mountain Home, Nr April-July46 58 71 81 91 117
Currant Ck
Currant Ck Res April-July8.6 13 16.5 83 23 27
Strawberry
Solider Springs,nr April-July26 38 47 66 67 92
Starvation Res, Duchesne, Nr April-July47 69 80 71 117 155
Duchesne
Duchesne, Nr, Knight Div, Abv April-July96 125 154 79 188 235
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July34 43 51 77 65 79
Yellowstone
Altonah, Nr April-July28 39 47 77 56 70
Whiterocks
Whiterocks, Nr April-July18.4 27 32 59 41 60
Uinta
Neola, Nr April-July27 41 54 73 68 86
Duchesne
Myton April-July104 168 225 68 305 415
Randlett, Nr April-July115 178 240 62 320 445


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-July4.6 9.7 13 84 16.5 21
Fish Ck
Scofield, Nr, Reservoir, Abv April-July15 19.7 25 83 33 37
Price
Scofield Res, Scofield, Nr April-July18.8 26 34 83 46 51
Green
Green River, Ut April-July1190 1530 2150 73 2670 3500
Huntington Ck
Electric Lake April-July5 6.9 11 83 15.7 19
Power Plant, Blo April-July20 27 35 88 46 52
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July30 38 48 86 58 73
Ferron Ck
Ferron, Nr April-July20 27 34 89 41 51
Muddy Ck
Emery, Nr April-July9 12.7 14 70 20 26


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 180 210 95 260 320
Willow Ck
Willow Ck Res, Granby, Nr April-July21 33 44 94 60 77
Fraser
Winter Park April-July12 15 17.9 92 21 24
Williams Fork
Williams Fork Res, Parshall, Nr April-July54 68 80 83 98 117
Muddy Ck
Wolford Mountain Reservoir April-July22 35 46 85 60 76
Blue
Dillon Res April-July98 120 141 87 168 200
Green Mtn Res April-July155 195 230 84 280 335
Colorado
Kremmling, Nr April-July470 620 760 88 940 1140
Eagle
Gypsum, Blo April-July195 240 280 84 350 435
Colorado
Dotsero, Nr April-July780 1000 1210 86 1520 1860
Frying Pan
Ruedi Res, Basalt, Nr April-July74 92 110 79 135 165
Roaring Fork
Glenwood Springs April-July395 480 550 80 660 795
Colorado
Glenwood Springs, Blo April-July1200 1550 1820 86 2250 2730
Cameo, Nr April-July1340 1700 2000 85 2500 3100
Plateau Ck
Cameo, Nr April-July50 70 85 69 115 155
Colorado
Cisco, Nr April-July2400 2900 3300 74 4000 5000
Lake Powell, Glen Cyn Dam, At April-July2600 3450 4550 64 5580 7600


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-July50 62 75 76 88 115
Almont April-July80 100 113 73 130 183
East
Almont April-July90 120 137 75 172 235
Gunnison
Gunnison, Nr April-July190 240 265 72 335 465
Tomichi Ck
Gunnison April-July23 38 48 65 58 88
Lake Fork
Gateview April-July60 82 98 80 110 138
Gunnison
Blue Mesa Res April-July360 430 500 74 610 755
Morrow Point Res April-July405 460 545 74 650 800
Crystal Res April-July470 520 610 73 720 865
Muddy Ck
Paonia Res, Bardine, Nr March-June40 52 65 68 73 100
April-July40 52 65 67 73 100
Nf Gunnison
Somerset, Nr April-July160 190 215 73 260 330
Surface Ck
Cedaredge April-July9 11 14 83 16 21
Uncompahgre
Ridgway Res April-July50 68 74 73 88 110
Colona April-July55 79 88 64 110 145
Delta April-July35 50 64 57 86 125
Gunnison
Grand Junction, Nr April-July750 900 1030 70 1300 1570


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-July106 135 170 69 220 270
Mcphee Res April-July110 145 190 64 260 325
San Miguel
Placerville, Nr April-July50 71 83 65 98 130
Dolores
Cisco, Nr April-July175 250 330 58 410 575


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-July80 105 125 58 150 210
Carracas, Nr April-July140 179 215 57 265 355
Navajo Res, Archuleta, Nr April-July230 300 370 50 510 700
Farmington April-July350 500 565 51 750 990
Bluff, Nr April-July320 490 545 50 725 990
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July20 28 33 61 41 53
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July23 32 37 57 48 64
Piedra
Arboles, Nr April-July55 85 105 50 135 205
Los Pinos
Vallecito Res, Bayfield, Nr April-July78 100 125 64 150 195
Animas
Durango April-July170 230 275 66 305 370
Florida
Lemon Res, Durango, Nr April-July18 24 33 60 41 58
La Plata
Hesperus April-July7 11 15 65 21 25
Mancos
Mancos, Nr April-July9 13 15.5 50 21 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 184.1 105 53 203.6 116 175.3 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 15.2 98 40 29.9 193 15.5 38.3
Blacks Fork
Meeks Cabin 4.1 40 14 8.7 84 10.3 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 3.5 60 25 5.8 101 5.8 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 3253.2 105 87 3343.2 108 3094.9 3749.0
untitled Strawberry
Solider Springs,nr 841.6 128 76 929.4 141 659.7 1105.9
Starvation Res, Duchesne, Nr 125.1 93 76 150.0 112 134.1 165.3
untitled Rock Ck
Upper Stillwater Res 9.4 90 30 9.3 90 10.4 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 10.6 47 29 23.7 106 22.4 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 11.3 65 44 19.1 109 17.5 25.7
untitled Price
Scofield Res, Scofield, Nr 24.3 85 37 48.4 170 28.5 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 30.3 76 48 45.5 115 39.7 62.5
untitled Huntington Ck
Electric Lake -9999.0 -99 -99 25.1 128 19.6 31.5
untitled
TOTAL 4512.8 107 80 4841.8 114 4214.2 5669.0


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 423.9 113 86 511.6 136 375.1 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 7.9 104 87 7.4 97 7.6 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 69.7 105 72 66.0 99 66.5 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 34.8 77 53 55.0 122 45.1 66.0
untitled Blue
Dillon Res 182.6 80 72 241.3 106 226.9 254.0
Green Mtn Res 58.0 65 39 73.6 82 89.8 146.9
untitled Homestake Ck
Homestake Res 41.2 125 96 41.1 125 32.9 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 60.0 78 59 72.1 94 76.8 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 10.4 87 32 10.4 87 12.0 32.9
untitled Taylor
Taylor Park Res 59.0 87 56 76.2 112 68.1 106.2
untitled Gunnison
Blue Mesa Res 248.8 45 30 592.6 108 549.9 829.5
Morrow Point Res 107.6 96 92 111.0 99 111.6 117.0
Crystal Res 14.8 96 84 15.9 103 15.4 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 2.8 66 17 2.2 52 4.2 16.7
untitled Uncompahgre
Ridgway Res 45.9 67 55 60.3 88 68.8 83.0
untitled Dolores
Mcphee Res 168.0 62 44 285.5 106 270.1 381.1
untitled
TOTAL 1535.3 76 55 2222.1 110 2020.8 2792.1
Colorado
Lake Powell 10098.9 57 42 14067.6 79 17744.8 24322.0
untitled
TOTAL 10098.9 57 42 14067.6 79 17744.8 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 33.8 54 27 64.9 104 62.1 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 878.7 66 52 1269.6 95 1341.1 1696.0
untitled Florida
Lemon Res, Durango, Nr 6.9 33 17 18.7 90 20.7 39.8
untitled
TOTAL 919.3 65 49 1353.1 95 1423.8 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