Lake Powell Water Supply Outlook, January 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-July135 180 210 86 250 315
Pine Ck
Fremont Lk, Abv April-July58 70 84 86 95 115
New Fork
Big Piney, Nr April-July155 230 270 76 330 440
Green
Fontenelle Reservoir, Fontenelle, Nr April-July280 450 570 79 735 950
Big Sandy
Farson, Nr April-July20 31 38 73 44 61
Green
Green River, Wy, Nr April-July270 450 575 79 735 980
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July24 30 40 74 55 72
Viva Naughton Reservoir April-July30 40 52 70 80 105
Blacks Fork
Robertson, Nr April-July50 72 85 96 98 120
Ef Smiths Fork
Stateline Reservoir, Robertson,nr April-July19 23 28 108 31 38
Green
Flaming Gorge Reservoir April-July430 610 830 85 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-July14 16 21 91 24 30
Steamboat Springs April-July145 185 240 92 275 340
Elk
Milner, Nr April-July205 260 335 105 380 420
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July30 50 73 100 84 100
Yampa
Maybell, Nr April-July535 660 925 99 1100 1260
Little Snake
Slater, Nr April-July80 110 160 103 180 210
Dixon, Nr April-July160 220 340 99 400 500
Lily, Nr April-July160 220 350 101 400 560
Yampa
Deerlodge Park April-July690 910 1250 101 1450 1750
White
Meeker, Nr April-July170 205 265 95 300 335
Watson, Nr April-July180 215 280 100 315 360


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-July12 17 20 95 24 29
Ashley Ck
Vernal, Nr April-July26 38 44 88 55 70
West Fork Duchesne
Vat Diversion, Blo April-July9 13 16 86 23 27
Duchesne
Tabiona, Nr April-July63 83 100 93 120 140
Rock Ck
Upper Stillwater Reservoir April-July45 62 73 99 88 110
South Fork Rock Ck
Docs Div, Blo April-July4 5.5 7 96 8.5 11.5
Rock Ck
Mountain Home, Nr April-July58 73 88 100 108 135
Currant Ck
Currant Ck Reservoir April-July10 16 20 100 25 31
Strawberry
Strawberry Reservoir, Soldier Springs April-July22 35 45 63 66 90
Starvation Reservoir, Duchesne, Nr April-July55 82 95 85 140 180
Duchesne
Duchesne, Nr, Knight Div, Abv April-July120 150 185 95 220 270
Lake Fork
Moon Lake Reservoir, Mtn Home, Nr April-July40 50 60 91 74 90
Yellowstone
Altonah, Nr April-July42 52 62 102 74 90
Whiterocks
Whiterocks, Nr April-July30 40 50 93 59 80
Uinta
Neola, Nr April-July43 62 75 101 88 110
Duchesne
Myton April-July150 215 300 91 390 510
Randlett, Nr April-July160 235 340 88 430 580


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-July5.1 9.1 14.5 94 22 30
Fish Ck
Scofield, Nr, Reservoir, Abv April-July14.5 20 27 90 35 46
Price
Scofield Reservoir, Scofield, Nr April-July21 28 37 90 48 63
Green
Green River, Ut April-July1550 2180 2700 91 3300 4300
Huntington Ck
Electric Lake April-July6.1 7.8 10.5 79 16.8 21
Power Plant, Blo April-July25 29 39 98 53 70
Seeley Ck
Joes Vly Reservoir, Orangeville, Nr April-July31 44 51 91 63 93
Ferron Ck
Ferron, Nr April-July21 30 36 95 45 67
Muddy Ck
Emery, Nr April-July11.9 15.1 18.7 94 26 35


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-July135 170 200 91 250 320
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July18 30 41 87 55 74
Fraser
Winter Park April-July13 16.2 19.4 100 22 25
Williams Fork
Williams Fork Reservoir, Parshall April-July60 75 88 92 110 130
Muddy Ck
Wolford Mountain Reservoir April-July28 42 54 100 70 85
Blue
Dillon Reservoir April-July110 140 160 98 190 225
Green Mtn Reservoir April-July180 225 265 96 315 375
Colorado
Kremmling, Nr April-July510 660 800 93 1000 1220
Eagle
Gypsum, Blo April-July200 250 290 87 360 450
Colorado
Dotsero, Nr April-July830 1070 1270 91 1600 1970
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July85 105 125 90 150 185
Roaring Fork
Glenwood Springs April-July440 530 600 87 720 860
Colorado
Glenwood Springs, Blo April-July1300 1650 1950 92 2350 2920
Cameo, Nr April-July1430 1800 2130 90 2650 3260
Plateau Ck
Cameo, Nr April-July55 72 87 70 120 165
Colorado
Cisco, Nr April-July2750 3250 3750 84 4550 5500
Lake Powell, Glen Cyn Dam, At April-July3600 4600 5900 82 7280 9400


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-July64 79 85 86 101 131
Almont April-July99 122 133 86 152 210
East
Almont April-July89 126 138 76 175 240
Gunnison
Gunnison, Nr April-July198 265 290 78 365 515
Tomichi Ck
Gunnison April-July43 63 73 99 87 119
Lake Fork
Gateview April-July81 103 119 97 129 164
Gunnison
Blue Mesa Reservoir April-July420 505 590 87 705 865
Morrow Point Reservoir April-July465 540 645 87 755 930
Crystal Reservoir April-July540 615 725 87 855 1050
Muddy Ck
Paonia Reservoir, Bardine, Nr March-June42 52 65 68 74 105
April-July40 52 65 67 74 110
Nf Gunnison
Somerset, Nr April-July146 184 210 71 255 330
Surface Ck
Cedaredge April-July8.1 9.8 12 71 13.2 20
Uncompahgre
Ridgway Reservoir April-July61 80 87 86 102 128
Colona April-July73 102 112 82 136 180
Delta April-July51 74 86 76 110 157
Gunnison
Grand Junction, Nr April-July880 1050 1200 81 1530 1810


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-July154 190 220 90 270 315
Mcphee Reservoir April-July172 210 260 88 325 400
San Miguel
Placerville, Nr April-July65 88 104 81 124 159
Dolores
Cisco, Nr April-July270 360 460 81 550 775


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-July125 153 170 79 198 265
Carracas, Nr April-July210 260 295 78 355 475
Navajo Reservoir, Archuleta, Nr April-July365 500 550 75 745 955
Farmington April-July565 750 820 75 1080 1360
Bluff, Nr April-July520 725 805 73 1050 1360
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July31 39 43 80 52 67
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July35 44 50 77 62 80
Piedra
Arboles, Nr April-July106 136 165 79 205 270
Los Pinos
Vallecito Reservoir, Bayfield, Nr April-July112 139 160 82 186 235
Animas
Durango April-July225 305 350 84 390 455
Florida
Lemon Reservoir, Durango, Nr April-July29 37 45 82 52 69
La Plata
Hesperus April-July12.9 17.8 22 96 26 32
Mancos
Mancos, Nr April-July14 19.3 23 74 31 44

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 207.5 118 60 184.1 105 175.3 344.8
untitled Big Sandy
Big Sandy Reservoir, Nr Farson 22.1 143 58 15.2 98 15.5 38.3
Blacks Fork
Meeks Cabin 9.0 87 30 4.1 40 10.3 29.9
untitled Ef Smiths Fork
Stateline Reservoir, Robertson,nr 5.8 100 42 3.5 60 5.8 13.9
untitled Green
Flaming Gorge Reservoir 3327.1 108 89 3253.2 105 3094.9 3749.0
untitled Strawberry
Strawberry Reservoir, Soldier Springs 954.4 145 86 841.8 128 659.7 1105.9
Starvation Reservoir, Duchesne, Nr 142.3 106 86 125.0 93 134.1 165.3
untitled Rock Ck
Upper Stillwater Reservoir 20.4 196 65 9.4 90 10.4 31.4
untitled Lake Fork
Moon Lake Reservoir, Mtn Home, Nr 26.5 118 73 10.6 47 22.4 36.5
untitled Big Brush Ck
Red Fleet Reservoir, Vernal, Nr 20.0 114 78 11.3 65 17.5 25.7
untitled Price
Scofield Reservoir, Scofield, Nr 50.2 176 76 24.3 85 28.5 65.8
untitled Seeley Ck
Joes Vly Reservoir, Orangeville, Nr 46.7 118 75 30.3 76 39.7 62.5
untitled Huntington Ck
Electric Lake 24.5 125 78 -9999.0 -99 19.6 31.5
untitled
TOTAL 4856.5 115 85 4512.9 107 4233.8 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 454.9 121 93 422.8 113 375.1 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 8.1 107 89 7.9 104 7.6 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 77.6 117 80 69.7 105 66.5 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 51.2 114 78 34.8 77 45.1 66.0
untitled Blue
Dillon Reservoir 227.0 100 89 182.6 80 226.9 254.0
Green Mtn Reservoir 74.2 83 51 57.9 64 89.8 146.9
untitled Homestake Ck
Homestake Reservoir 41.2 125 96 41.2 125 32.9 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 75.6 98 74 60.0 78 76.8 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 5.8 48 18 5.8 48 12.0 32.9
untitled Taylor
Taylor Park Reservoir 75.3 111 71 59.0 87 68.1 106.2
untitled Gunnison
Blue Mesa Reservoir 587.5 107 71 248.8 45 549.9 829.5
Morrow Point Reservoir 108.4 97 93 107.5 96 111.6 117.0
Crystal Reservoir 15.1 98 86 14.8 96 15.4 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 2.5 59 15 2.8 66 4.2 16.7
untitled Uncompahgre
Ridgway Reservoir 64.5 94 78 45.9 67 68.8 83.0
untitled Dolores
Mcphee Reservoir 288.8 107 76 168.0 62 270.1 381.1
untitled
TOTAL 2157.7 107 77 1529.5 76 2020.8 2792.1
Colorado
Lake Powell 12603.9 71 52 10098.9 57 17744.8 24322.0
untitled
TOTAL 12603.9 71 52 10098.9 57 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 Reservoir, Bayfield, Nr 75.4 121 60 33.8 54 62.1 125.4
untitled San Juan
Navajo Reservoir, Archuleta, Nr 1325.7 99 78 878.7 66 1341.1 1696.0
untitled Florida
Lemon Reservoir, Durango, Nr 17.6 85 44 6.9 33 20.7 39.8
untitled
TOTAL 1418.8 100 76 919.3 65 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