Lake Powell Water Supply Outlook, March 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-July155 185 205 84 235 270
Pine Ck
Fremont Lk, Abv April-July72 80 95 97 98 111
New Fork
Big Piney, Nr April-July250 285 330 93 380 450
Green
Fontenelle Res, Fontenelle Nr April-July450 535 630 87 720 900
Big Sandy
Farson, Nr April-July35 46 51 98 61 74
Green
Green River, Wy, Nr April-July450 555 640 88 740 915
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July26 29 36 67 45 59
Viva Naughton Res April-July33 38 46 62 59 86
Blacks Fork
Robertson, Nr April-July64 71 84 94 100 121
Ef Smiths Fork
Stateline Res, Robertson,nr April-July19 23 25 96 29 33
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July580 670 830 85 1060 1350


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-July17.9 19.1 21 91 23 34
Steamboat Springs April-July190 235 260 100 310 365
Elk
Milner, Nr April-July265 320 345 108 375 435
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July43 56 63 86 71 92
Yampa
Maybell, Nr April-July665 825 960 103 1080 1290
Little Snake
Slater, Nr April-July103 132 150 96 168 205
Dixon, Nr April-July210 280 330 96 375 500
Lily, Nr April-July210 285 340 99 395 525
Yampa
Deerlodge Park April-July875 1120 1290 104 1470 1760
White
Meeker, Nr April-July192 235 250 89 275 355
Watson, Nr April-July200 245 265 95 295 400


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-July13.4 18.1 20 95 23 31
Ashley Ck
Vernal, Nr April-July30 38 47 94 52 66
West Fork Duchesne
Vat Diversion, Blo April-July18 21 25 134 27 31
Duchesne
Tabiona, Nr April-July92 104 115 106 129 142
Rock Ck
Upper Stillwater Res April-July64 75 85 115 93 106
South Fork Rock Ck
Docs Div, Blo April-July6.2 7.6 8.7 119 9.7 11.4
Rock Ck
Mountain Home, Nr April-July75 88 101 115 112 127
Currant Ck
Currant Ck Res April-July21 25 29 145 32 36
Strawberry
Solider Springs,nr April-July62 73 88 124 102 120
Starvation Res, Duchesne, Nr April-July105 123 160 143 186 215
Duchesne
Duchesne, Nr, Knight Div, Abv April-July162 189 215 111 235 260
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July53 67 76 115 81 96
Yellowstone
Altonah, Nr April-July48 63 69 113 79 93
Whiterocks
Whiterocks, Nr April-July31 41 53 98 58 71
Uinta
Neola, Nr April-July54 72 83 112 90 112
Duchesne
Myton April-July270 330 405 123 460 520
Randlett, Nr April-July280 340 430 112 515 610


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-July15.6 21 25 161 29 33
Fish Ck
Scofield, Nr, Reservoir, Abv April-July32 36 42 140 46 54
Price
Scofield Res, Scofield, Nr April-July45 50 59 144 66 78
Green
Green River, Ut April-July2200 2650 3000 101 3690 4200
Huntington Ck
Electric Lake April-July15.6 17.6 20 150 23 27
Power Plant, Blo April-July47 52 60 150 66 80
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July54 63 69 123 77 91
Ferron Ck
Ferron, Nr April-July34 41 47 124 52 59
Muddy Ck
Emery, Nr April-July14.7 20 23 116 27 33


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-July160 190 225 102 260 305
Willow Ck
Willow Ck Res, Granby, Nr April-July34 42 52 111 62 80
Fraser
Winter Park April-July14.5 17 19.5 101 22 24
Williams Fork
Williams Fork Res, Parshall, Nr April-July68 80 94 98 106 124
Muddy Ck
Wolford Mountain Reservoir April-July44 52 62 115 72 88
Blue
Dillon Res April-July135 160 180 110 200 220
Green Mtn Res April-July215 255 290 105 325 365
Colorado
Kremmling, Nr April-July660 780 900 105 1020 1210
Eagle
Gypsum, Blo April-July265 310 360 107 400 465
Colorado
Dotsero, Nr April-July1110 1280 1480 106 1700 2000
Frying Pan
Ruedi Res, Basalt, Nr April-July100 125 145 104 160 182
Roaring Fork
Glenwood Springs April-July530 620 700 101 780 880
Colorado
Glenwood Springs, Blo April-July1700 1980 2220 105 2520 2960
Cameo, Nr April-July1900 2220 2550 108 2850 3350
Plateau Ck
Cameo, Nr April-July120 145 165 133 185 210
Colorado
Cisco, Nr April-July3700 4300 4800 108 5300 6100
Lake Powell, Glen Cyn Dam, At April-July5300 6610 7300 102 8100 10700


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-July80 89 102 103 112 135
Almont April-July130 144 162 105 176 220
East
Almont April-July150 175 195 107 215 255
Gunnison
Gunnison, Nr April-July310 355 400 108 430 545
Tomichi Ck
Gunnison April-July50 68 80 108 91 121
Lake Fork
Gateview April-July94 119 135 110 155 185
Gunnison
Blue Mesa Res April-July570 660 740 110 820 1020
Morrow Point Res April-July640 730 810 109 890 1090
Crystal Res April-July725 815 895 107 975 1170
Muddy Ck
Paonia Res, Bardine, Nr March-June75 83 94 98 112 130
April-July76 84 95 98 113 131
Nf Gunnison
Somerset, Nr April-July240 260 290 98 320 410
Surface Ck
Cedaredge April-July17 20 23 137 25 28
Uncompahgre
Ridgway Res April-July66 88 98 97 105 136
Colona April-July89 120 130 95 145 195
Delta April-July59 90 105 93 120 175
Gunnison
Grand Junction, Nr April-July1180 1400 1520 103 1670 2200


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-July190 240 275 112 300 375
Mcphee Res April-July230 290 330 112 360 480
San Miguel
Placerville, Nr April-July82 109 120 94 140 168
Dolores
Cisco, Nr April-July410 540 600 106 680 885


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-July148 178 205 95 220 280
Carracas, Nr April-July250 300 360 95 400 500
Navajo Res, Archuleta, Nr April-July455 570 690 94 790 1010
Farmington April-July680 860 1060 96 1180 1530
Bluff, Nr April-July660 880 1060 96 1180 1560
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July39 45 55 102 61 70
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July44 52 62 95 69 81
Piedra
Arboles, Nr April-July130 162 195 93 225 285
Los Pinos
Vallecito Res, Bayfield, Nr April-July150 183 205 106 220 270
Animas
Durango April-July290 370 425 102 460 550
Florida
Lemon Res, Durango, Nr April-July39 47 56 102 63 77
La Plata
Hesperus April-July17 20 25 109 27 32
Mancos
Mancos, Nr April-July18 24 30 97 36 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 Res, Fontenelle Nr 130.9 103 38 177.6 139 127.6 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 31.6 210 83 24.7 164 15.1 38.3
Blacks Fork
Meeks Cabin 11.1 90 37 12.5 101 12.3 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 6.1 114 44 6.6 123 5.4 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 3194.0 106 85 3088.1 102 3015.6 3749.0
untitled Strawberry
Solider Springs,nr 932.0 141 84 784.2 119 660.2 1105.9
Starvation Res, Duchesne, Nr 165.3 114 100 129.4 90 144.5 165.3
untitled Rock Ck
Upper Stillwater Res 9.2 120 29 12.7 166 7.6 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 25.6 96 70 26.6 100 26.6 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 20.3 110 79 21.3 115 18.5 25.7
untitled Price
Scofield Res, Scofield, Nr 51.4 168 78 16.6 54 30.6 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 45.6 113 73 31.0 77 40.2 62.5
untitled Huntington Ck
Electric Lake 23.9 127 76 16.1 86 18.8 31.5
untitled
TOTAL 4646.9 113 82 4347.3 105 4123.0 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 363.3 109 74 463.8 140 332.0 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.5 103 93 8.2 99 8.2 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 65.5 105 68 66.3 106 62.4 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 33.7 76 51 54.2 122 44.2 66.0
untitled Blue
Dillon Res 179.1 82 70 238.9 109 219.3 254.0
Green Mtn Res 52.7 72 36 68.3 93 73.5 146.9
untitled Homestake Ck
Homestake Res 33.6 109 78 41.0 134 30.7 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 56.5 83 55 67.1 99 67.9 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 6.9 52 21 11.5 87 13.2 32.9
untitled Taylor
Taylor Park Res 59.6 91 56 72.3 110 65.7 106.2
untitled Gunnison
Blue Mesa Res 247.7 51 30 547.1 113 482.2 829.5
Morrow Point Res 107.2 96 92 108.4 98 111.1 117.0
Crystal Res 15.6 99 89 16.1 102 15.8 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 4.1 89 25 3.6 78 4.7 16.7
untitled Uncompahgre
Ridgway Res 46.9 68 57 61.6 89 69.4 83.0
untitled Dolores
Mcphee Res 167.3 61 44 284.1 104 272.3 381.1
untitled
TOTAL 1448.2 77 52 2112.7 113 1872.6 2792.1
Colorado
Lake Powell 9260.7 54 38 13345.8 78 17054.6 24322.0
untitled
TOTAL 9260.7 54 38 13345.8 78 17054.6 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 40.7 64 32 69.8 110 63.5 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 865.2 67 51 1246.0 96 1292.2 1696.0
untitled Florida
Lemon Res, Durango, Nr 7.0 34 18 18.7 89 21.0 39.8
untitled
TOTAL 913.0 66 49 1334.5 97 1376.7 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