Lake Powell Water Supply Outlook, May 1, 2016

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-July147 162 179 73 199 210
May-July128 143 160 71 180 193
Pine Ck
Fremont Lk, Abv April-July58 69 76 78 84 97
May-July55 66 73 76 81 94
New Fork
Big Piney, Nr April-July164 210 230 65 275 335
May-July143 191 210 64 255 315
Green
Fontenelle Res, Fontenelle Nr April-July400 470 530 73 605 675
May-July310 380 440 69 515 585
Big Sandy
Farson, Nr April-July31 37 41 79 46 56
May-July28 34 38 79 43 53
Green
Green River, Wy, Nr April-July395 470 525 72 610 705
May-July300 375 430 67 515 610
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July26 30 33 61 38 42
May-July18 22 25 52 30 34
Viva Naughton Res April-July36 40 44 59 50 57
May-July21 25 29 47 35 42
Blacks Fork
Robertson, Nr April-July64 70 75 84 82 92
May-July59 65 70 82 77 87
Ef Smiths Fork
Stateline Res, Robertson,nr April-July22 23 25 96 27 30
May-July21 22 24 92 26 29
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July615 680 770 79 905 980
May-July475 540 630 75 765 840


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-July18.5 20 21 91 22 26
May-July10.2 12 12.7 79 14 17.3
Steamboat Springs April-July255 280 295 113 305 340
May-July200 225 240 109 250 285
Elk
Milner, Nr April-July305 335 350 109 365 405
May-July255 285 300 103 315 355
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July63 69 73 100 76 85
May-July42 48 52 104 55 64
Yampa
Maybell, Nr April-July815 910 950 102 1010 1100
May-July615 710 750 97 810 900
Little Snake
Slater, Nr April-July120 133 144 92 152 174
May-July98 111 122 88 130 152
Dixon, Nr April-July250 280 310 90 330 365
May-July198 225 255 86 275 310
Lily, Nr April-July260 295 325 94 345 390
May-July199 235 265 91 285 330
Yampa
Deerlodge Park April-July1050 1170 1250 101 1300 1500
May-July800 920 1000 98 1050 1250
White
Meeker, Nr April-July200 220 230 82 240 290
May-July165 186 195 80 205 255
Watson, Nr April-July215 235 245 88 255 310
May-July173 195 205 87 215 270


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-July15.3 17.1 18.6 89 19.7 22
May-July12.8 14.6 16.1 88 17.2 20
Ashley Ck
Vernal, Nr April-July36 41 43 86 45 52
May-July33 38 40 85 42 49
West Fork Duchesne
Vat Diversion, Blo April-July8.1 9 10 54 11 12.3
May-July7 7.9 8.9 51 9.9 11.2
Duchesne
Tabiona, Nr April-July61 65 71 66 79 84
May-July52 56 62 63 70 75
Rock Ck
Upper Stillwater Res April-July52 60 64 86 69 76
May-July48 56 60 85 65 72
South Fork Rock Ck
Docs Div, Blo April-July4.4 4.9 5.2 71 5.7 6.3
May-July3.9 4.4 4.7 68 5.2 5.8
Rock Ck
Mountain Home, Nr April-July57 66 71 81 77 85
May-July52 61 66 79 72 80
Currant Ck
Currant Ck Res April-July8.2 9.1 10 50 10.9 11.9
May-July6.5 7.4 8.3 49 9.2 10.2
Strawberry
Solider Springs,nr April-July18.8 21 24 34 28 30
May-July10.7 13 16 28 19.5 22
Starvation Res, Duchesne, Nr April-July33 36 41 37 45 50
May-July22 25 30 33 34 39
Duchesne
Duchesne, Nr, Knight Div, Abv April-July120 129 141 73 153 162
May-July105 114 126 70 138 147
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July40 44 48 73 51 60
May-July37 41 45 71 48 57
Yellowstone
Altonah, Nr April-July41 46 51 84 55 61
May-July37 42 47 82 51 57
Whiterocks
Whiterocks, Nr April-July32 36 41 76 44 52
May-July30 34 39 76 42 50
Uinta
Neola, Nr April-July47 52 59 80 64 77
May-July44 49 56 79 61 74
Duchesne
Myton April-July135 154 173 52 193 220
May-July109 128 147 50 167 196
Randlett, Nr April-July148 169 192 50 215 265
May-July120 141 164 48 187 235


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-July6.7 7.8 8.3 54 9.5 10.9
May-July5.1 6.2 6.7 56 7.9 9.3
Fish Ck
Scofield, Nr, Reservoir, Abv April-July13.3 15.2 16.8 56 18.9 21
May-July10.8 12.7 14.3 55 16.4 18.6
Price
Scofield Res, Scofield, Nr April-July16.3 19.4 21 51 24 27
May-July12.4 15.5 17.4 50 20 23
Green
Green River, Ut April-July1960 2180 2380 80 2600 2980
May-July1580 1800 2000 79 2220 2600
Huntington Ck
Electric Lake April-July4.5 4.9 5.2 39 6.5 7.7
May-July3.3 3.7 4 34 5.3 6.5
Power Plant, Blo April-July18.7 19.4 20 50 24 27
May-July15.4 16.1 17 46 21 24
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July27 30 32 57 34 40
May-July24 27 29 56 31 37
Ferron Ck
Ferron, Nr April-July20 23 25 66 26 30
May-July18.4 21 23 66 24 28
Muddy Ck
Emery, Nr April-July8.8 10.2 11.1 56 11.9 13.8
May-July7.5 8.9 9.8 54 10.6 12.5


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 180 195 89 205 230
May-July145 165 180 88 190 215
Willow Ck
Willow Ck Res, Granby, Nr April-July40 48 52 111 60 65
May-July35 43 47 109 55 60
Fraser
Winter Park April-July18 19.5 21 108 22 25
May-July17 18.5 20 108 21 24
Williams Fork
Williams Fork Res, Parshall, Nr April-July82 89 95 99 102 117
May-July75 82 88 98 95 110
Muddy Ck
Wolford Mountain Reservoir April-July42 50 55 102 62 72
May-July35 43 48 104 55 65
Blue
Dillon Res April-July140 153 170 104 178 200
May-July130 143 160 105 168 190
Green Mtn Res April-July230 255 270 98 290 330
May-July210 235 250 98 270 310
Colorado
Kremmling, Nr April-July730 810 850 99 910 1040
May-July650 730 770 98 830 960
Eagle
Gypsum, Blo April-July250 280 305 91 330 400
May-July230 260 285 90 310 380
Colorado
Dotsero, Nr April-July1120 1250 1340 96 1430 1680
May-July1000 1130 1220 95 1310 1560
Frying Pan
Ruedi Res, Basalt, Nr April-July102 112 125 90 132 172
May-July95 105 118 91 125 165
Roaring Fork
Glenwood Springs April-July495 530 575 83 615 745
May-July450 485 530 83 570 700
Colorado
Glenwood Springs, Blo April-July1670 1820 1940 92 2120 2420
May-July1500 1650 1770 92 1950 2250
Cameo, Nr April-July1790 1990 2140 91 2340 2690
May-July1600 1800 1950 91 2150 2500
Plateau Ck
Cameo, Nr April-July80 92 115 93 135 160
May-July60 72 95 91 115 140
Colorado
Cisco, Nr April-July3230 3530 3800 86 4080 4730
May-July2700 3000 3270 85 3550 4200
Lake Powell, Glen Cyn Dam, At April-July4210 5060 5500 77 6060 7110
May-July3400 4250 4690 77 5250 6300


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-July71 77 82 83 87 99
May-July62 68 73 81 78 90
Almont April-July109 118 124 80 132 154
May-July95 104 110 78 118 140
East
Almont April-July112 118 130 71 141 157
May-July95 101 113 68 124 140
Gunnison
Gunnison, Nr April-July245 255 270 73 285 325
May-July210 220 235 70 250 290
Tomichi Ck
Gunnison April-July42 49 54 73 61 74
May-July33 40 45 73 52 65
Lake Fork
Gateview April-July93 107 114 93 124 143
May-July85 99 106 91 116 135
Gunnison
Blue Mesa Res April-July455 505 525 78 565 660
May-July380 430 450 75 490 585
Morrow Point Res April-July495 550 570 77 610 700
May-July415 470 490 75 530 620
Crystal Res April-July560 605 630 75 675 765
May-July470 515 540 73 585 675
Muddy Ck
Paonia Res, Bardine, Nr March-June69 73 80 83 85 96
April-July66 72 79 81 87 98
May-June41 45 52 75 57 68
May-July43 49 56 75 62 74
Nf Gunnison
Somerset, Nr April-July198 210 230 78 245 280
May-July155 166 187 78 200 235
Surface Ck
Cedaredge April-July11.3 12.8 14.8 88 17.3 19.3
May-July8 9.5 11.5 82 14 16
Uncompahgre
Ridgway Res April-July74 79 93 92 98 111
May-July65 70 84 92 89 102
Colona April-July90 107 125 91 137 160
May-July75 92 110 92 122 145
Delta April-July79 91 104 92 114 134
May-July50 62 75 80 85 105
Gunnison
Grand Junction, Nr April-July995 1110 1200 81 1280 1450
May-July780 890 980 79 1060 1230


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-July172 184 197 80 215 230
May-July135 147 160 80 177 195
Mcphee Res April-July185 200 215 73 240 260
May-July140 156 170 77 195 215
San Miguel
Placerville, Nr April-July98 109 118 92 126 138
May-July85 96 105 93 113 125
Dolores
Cisco, Nr April-July355 385 410 73 450 490
May-July270 300 325 78 365 405


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-July166 180 188 87 196 205
May-July130 144 152 84 160 170
Carracas, Nr April-July260 280 295 78 310 330
May-July205 225 240 80 255 275
Navajo Res, Archuleta, Nr April-July440 490 520 71 545 620
May-July320 370 400 71 425 500
Farmington April-July645 715 765 70 810 935
May-July490 560 610 69 655 780
Bluff, Nr April-July640 710 765 70 815 955
May-July485 555 610 71 660 800
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July38 41 45 83 50 56
May-July31 34 38 84 43 49
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July41 46 51 78 54 60
May-July33 38 43 80 46 52
Piedra
Arboles, Nr April-July138 151 160 76 166 190
May-July98 111 120 78 126 150
Los Pinos
Vallecito Res, Bayfield, Nr April-July122 142 155 80 166 190
May-July97 117 130 76 141 165
Animas
Durango April-July260 290 315 76 340 395
May-July215 245 270 74 295 350
Florida
Lemon Res, Durango, Nr April-July32 35 40 73 45 51
May-July27 30 35 71 40 46
La Plata
Hesperus April-July13.9 15.4 16.9 73 18.9 21
May-July11 12.5 14 77 16 18
Mancos
Mancos, Nr April-July22 24 27 87 29 32
May-July16 18 21 88 23 26

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 173.5 139 50 185.1 148 125.0 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 24.8 117 65 26.5 124 21.3 38.3
Blacks Fork
Meeks Cabin 14.3 87 48 30.5 185 16.5 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 7.7 119 56 11.8 182 6.5 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 3213.5 106 86 3212.6 106 3040.4 3749.0
untitled Strawberry
Solider Springs,nr 807.1 119 73 846.0 125 676.1 1105.9
Starvation Res, Duchesne, Nr 164.6 108 100 164.3 108 151.9 165.3
untitled Rock Ck
Upper Stillwater Res 2.2 77 7 6.5 226 2.9 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 25.1 91 69 36.2 131 27.6 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 18.9 94 74 12.5 62 20.1 25.7
untitled Price
Scofield Res, Scofield, Nr 16.8 51 26 16.3 49 33.0 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 36.0 91 58 42.0 106 39.6 62.5
untitled Huntington Ck
Electric Lake 17.4 93 55 18.2 98 18.7 31.5
untitled
TOTAL 4522.1 108 79 4608.5 110 4179.6 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 380.6 122 78 491.3 158 311.8 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 7.8 101 85 7.5 97 7.7 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 76.7 126 79 83.7 137 60.9 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 47.0 99 71 49.7 104 47.7 66.0
untitled Blue
Dillon Res 239.3 112 94 247.1 116 213.6 254.0
Green Mtn Res 67.0 105 46 72.1 113 63.9 146.9
untitled Homestake Ck
Homestake Res 41.4 220 96 20.6 110 18.8 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 70.1 112 69 75.9 121 62.6 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 18.2 99 55 19.7 107 18.3 32.9
untitled Taylor
Taylor Park Res 71.0 116 67 82.1 134 61.2 106.2
untitled Gunnison
Blue Mesa Res 570.7 125 69 597.3 131 457.1 829.5
Morrow Point Res 111.1 99 95 109.5 98 111.8 117.0
Crystal Res 16.5 99 94 16.6 99 16.7 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 3.3 51 20 14.0 218 6.4 16.7
untitled Uncompahgre
Ridgway Res 68.0 102 82 71.6 108 66.6 83.0
untitled Dolores
Mcphee Res 299.1 93 78 208.6 65 323.0 381.1
untitled
TOTAL 2087.8 113 75 2167.6 117 1848.0 2792.1
Colorado
Lake Powell 11013.5 64 45 10836.8 63 17122.8 24322.0
untitled
TOTAL 11013.5 64 45 10836.8 63 17122.8 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 104.9 142 84 108.2 146 74.0 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 1491.0 110 88 1170.5 86 1361.0 1696.0
untitled Florida
Lemon Res, Durango, Nr 27.5 114 69 28.1 117 24.1 39.8
untitled
TOTAL 1623.4 111 87 1306.7 90 1459.0 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