Lake Powell Water Supply Outlook, May 1, 2014

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Alcorn
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		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Green
Daniel, Nr, Warren Bridge, At April-July315 355 145 395
May-July300 340 151 380
Pine Ck
Fremont Lk, Abv April-July101 119 121 136
May-July98 116 121 133
New Fork
Big Piney, Nr April-July370 475 134 570
May-July340 445 135 540
Green
Fontenelle Res, Fontenelle Nr April-July940 1130 156 1310
May-July840 1030 161 1210
Big Sandy
Farson, Nr April-July42 55 106 70
May-July39 52 108 67
Green
Green River, Wy, Nr April-July940 1140 156 1300
May-July840 1040 163 1200
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July53 68 126 81
May-July45 60 125 73
Viva Naughton Res April-July74 96 130 121
May-July58 80 129 105
Blacks Fork
Robertson, Nr April-July76 90 101 109
May-July70 84 99 103
Ef Smiths Fork
Stateline Res, Robertson,nr April-July22 26 100 31
May-July21 25 96 30
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July1030 1320 135 1580
May-July900 1190 141 1450


Yampa/White Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Yampa
Stagecoach Rsvr, Abv April-July23 28 122 38
May-July10.3 15.8 99 26
Steamboat Springs April-July315 360 138 425
May-July250 295 134 360
Elk
Milner, Nr April-July385 440 138 510
May-July325 380 131 450
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July82 95 130 112
May-July55 68 136 85
Yampa
Maybell, Nr April-July1040 1200 128 1350
May-July840 1000 129 1150
Little Snake
Slater, Nr April-July165 196 126 235
May-July138 169 122 210
Savery, Nr April-July300 375 109 460
May-July240 315 107 400
Lily, Nr April-July305 385 112 475
May-July250 330 114 420
Yampa
Deerlodge Park April-July1310 1550 125 1810
May-July1050 1290 126 1550
White
Meeker, Nr April-July235 275 98 340
May-July190 230 94 295
Watson, Nr April-July235 285 102 355
May-July190 240 102 310


Duchesne Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Big Brush Ck
Vernal, Nr, Red Fleet Res, Abv April-July6.2 8.6 41 12.2
May-July4.6 7 38 10.6
Ashley Ck
Vernal, Nr April-July15.3 23 46 29
May-July13.1 21 45 27
West Fork Duchesne
Vat Diversion, Blo April-July9.4 13.5 73 16.6
May-July8.3 12.4 72 15.5
Duchesne
Tabiona, Nr April-July71 86 80 105
May-July62 77 79 96
Rock Ck
Upper Stillwater Res April-July58 72 97 85
May-July54 68 96 81
South Fork Rock Ck
Docs Div, Blo April-July4.3 5.5 75 6.5
May-July3.8 5 72 6
Rock Ck
Mountain Home, Nr April-July68 82 93 96
May-July63 77 92 91
Currant Ck
Currant Ck Res April-July12.1 15 75 18.6
May-July10 12.9 75 16.5
Strawberry
Solider Springs,nr April-July28 36 51 47
May-July16.5 24 41 35
Starvation Res, Duchesne, Nr April-July53 65 58 80
May-July38 50 55 65
Duchesne
Duchesne, Nr, Knight Div, Abv April-July136 166 86 198
May-July120 150 84 182
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July53 62 94 75
May-July50 59 94 72
Yellowstone
Altonah, Nr April-July40 52 85 66
May-July37 49 86 63
Whiterocks
Whiterocks, Nr April-July18.9 27 50 39
May-July17 25 49 37
Uinta
Neola, Nr April-July42 53 72 71
May-July39 50 70 68
Duchesne
Myton April-July169 235 71 310
May-July140 205 69 280
Randlett, Nr April-July169 245 64 315
May-July140 215 62 285


Lower Green Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
White
Blo Tabbyune Ck, Soldier Summit, Nr April-July6.4 8.4 54 11.4
May-July4.5 6.5 55 9.5
Fish Ck
Scofield, Nr, Reservoir, Abv April-July17 22 73 28
May-July14 18.5 71 25
Price
Scofield Res, Scofield, Nr April-July22 28 68 37
May-July17.5 24 69 33
Green
Green River, Ut April-July2730 3310 112 3980
May-July2350 2930 115 3600
Huntington Ck
Electric Lake April-July6.7 8.4 63 11.6
May-July5.3 7 59 10.2
Power Plant, Blo April-July25 29 73 38
May-July22 26 70 35
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July38 47 84 56
May-July33 42 81 51
Ferron Ck
Ferron, Nr April-July28 34 89 40
May-July25 31 89 37
Muddy Ck
Emery, Nr April-July12.9 16.1 81 22
May-July11.4 14.6 81 20


Upper Colorado Mainstem Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Colorado
Lake Granby, Granby, Nr April-July270 320 145 370
May-July250 300 146 350
Willow Ck
Willow Ck Res, Granby, Nr April-July52 68 145 84
May-July43 59 137 75
Fraser
Winter Park April-July24 28 144 32
May-July23 27 145 31
Williams Fork
Williams Fork Res, Parshall, Nr April-July121 135 141 155
May-July110 124 138 144
Muddy Ck
Wolford Mountain Reservoir April-July78 90 167 108
May-July64 76 165 94
Blue
Dillon Res April-July220 250 153 285
May-July200 230 150 265
Green Mtn Res April-July370 405 147 465
May-July340 375 147 435
Colorado
Kremmling, Nr April-July1170 1300 151 1500
May-July1030 1160 148 1360
Eagle
Gypsum, Blo April-July335 395 118 475
May-July300 360 114 440
Colorado
Dotsero, Nr April-July1670 1940 139 2220
May-July1460 1730 135 2010
Frying Pan
Ruedi Res, Basalt, Nr April-July130 155 112 188
May-July117 142 109 175
Roaring Fork
Glenwood Springs April-July635 740 107 920
May-July565 670 105 850
Colorado
Glenwood Springs, Blo April-July2330 2700 128 3200
May-July2030 2400 124 2900
Cameo, Nr April-July2430 2950 125 3500
May-July2080 2600 121 3150
Plateau Ck
Cameo, Nr April-July67 105 85 145
May-July43 81 78 121
Colorado
Cisco, Nr April-July4250 5000 113 6000
May-July3590 4340 112 5340
Lake Powell, Glen Cyn Dam, At April-July6300 7550 105 9460
May-July5340 6590 108 8500


Gunnison Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Taylor
Taylor Park Res April-July110 128 129 150
May-July98 116 129 138
Almont April-July166 200 129 235
May-July145 180 128 215
East
Almont April-July200 230 126 260
May-July170 200 120 230
Gunnison
Gunnison, Nr April-July420 470 127 545
May-July360 410 122 485
Tomichi Ck
Gunnison April-July76 92 124 116
May-July55 71 115 95
Lake Fork
Gateview April-July112 133 108 156
May-July101 122 105 145
Gunnison
Blue Mesa Res April-July780 850 126 940
May-July650 720 120 810
Morrow Point Res April-July860 930 126 1020
May-July715 785 121 875
Crystal Res April-July970 1040 125 1130
May-July815 885 120 975
Muddy Ck
Paonia Res, Bardine, Nr March-June89 95 99 116
April-July90 96 99 117
May-June63 69 100 90
May-July68 74 99 95
Nf Gunnison
Somerset, Nr April-July270 290 98 335
May-July210 230 96 275
Surface Ck
Cedaredge April-July11.1 15.1 90 19.1
May-July8 12 85 16
Uncompahgre
Ridgway Res April-July80 91 90 109
May-July67 78 86 96
Colona April-July94 114 83 148
May-July80 100 83 134
Delta April-July70 85 75 119
May-July56 71 76 105
Gunnison
Grand Junction, Nr April-July1460 1660 112 1910
May-July1180 1380 111 1630


Dolores Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Dolores
Dolores April-July169 205 84 240
May-July130 165 83 200
Mcphee Res April-July194 220 75 260
May-July152 177 80 220
San Miguel
Placerville, Nr April-July104 122 95 137
May-July87 105 93 120
Dolores
Cisco, Nr April-July365 410 73 485
May-July280 325 78 400


San Juan Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
San Juan
Pagosa Springs April-July118 138 64 158
May-July80 100 56 120
Carracas, Nr April-July205 230 61 265
May-July150 175 58 210
Navajo Res, Archuleta, Nr April-July370 460 63 540
May-July245 335 59 415
Farmington April-July655 775 70 910
May-July480 600 68 735
Bluff, Nr April-July595 735 67 885
May-July440 580 68 730
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July25 31 57 37
May-July17 23 51 29
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July29 37 57 44
May-July22 30 56 37
Piedra
Arboles, Nr April-July122 139 66 154
May-July78 95 62 110
Los Pinos
Vallecito Res, Bayfield, Nr April-July134 167 86 205
May-July106 139 81 177
Animas
Durango April-July325 380 92 460
May-July275 330 90 410
Florida
Lemon Res, Durango, Nr April-July32 42 76 53
May-July24 35 71 45
La Plata
Hesperus April-July12 13.5 59 17
May-July8.5 10 55 13.5
Mancos
Mancos, Nr April-July11.2 14.2 46 18.2
May-July10 13 54 17

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 137.7 110 40 128.1 102 125.0 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 14.7 69 38 11.2 53 21.3 38.3
Blacks Fork
Meeks Cabin 22.2 135 74 10.1 62 16.5 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 8.1 125 58 5.2 80 6.5 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 2970.8 98 79 2999.8 99 3040.4 3749.0
untitled Strawberry
Solider Springs,nr 851.0 126 77 899.6 133 676.1 1105.9
Starvation Res, Duchesne, Nr 164.3 108 99 164.8 108 151.9 165.3
untitled Rock Ck
Upper Stillwater Res 2.4 84 8 6.6 228 2.9 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 26.1 94 71 13.7 50 27.6 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 12.5 62 49 15.0 75 20.1 25.7
untitled Price
Scofield Res, Scofield, Nr 20.5 62 31 32.3 98 33.0 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 34.4 87 55 33.7 85 39.6 62.5
untitled Huntington Ck
Electric Lake 17.9 96 57 19.3 103 18.7 31.5
untitled
TOTAL 4282.5 102 75 4339.5 104 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 295.7 95 60 182.2 58 311.8 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.1 106 89 8.1 106 7.7 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 75.2 123 78 45.4 75 60.9 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 46.3 97 70 26.9 56 47.7 66.0
untitled Blue
Dillon Res 206.4 97 81 161.8 76 213.6 254.0
Green Mtn Res 68.9 108 47 65.8 103 63.9 146.9
untitled Homestake Ck
Homestake Res 0.1 0 0 0.2 1 18.8 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 64.9 104 64 62.6 100 62.6 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 23.7 129 72 11.3 62 18.3 32.9
untitled Taylor
Taylor Park Res 70.3 115 66 59.2 97 61.2 106.2
untitled Gunnison
Blue Mesa Res 509.1 111 61 338.0 74 457.1 829.5
Morrow Point Res 106.1 95 91 106.5 95 111.8 117.0
Crystal Res 14.2 85 81 12.9 77 16.7 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 0.7 11 4 7.2 111 6.4 16.7
untitled Uncompahgre
Ridgway Res 67.3 101 81 60.4 91 66.6 83.0
untitled Dolores
Mcphee Res 223.3 69 59 197.9 61 323.0 381.1
untitled
TOTAL 1780.3 96 64 1346.6 73 1848.0 2792.1
Colorado
Lake Powell 9731.9 57 40 11422.0 67 17122.8 24322.0
untitled
TOTAL 9731.9 57 40 11422.0 67 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 105.8 143 84 62.7 85 74.0 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 1052.7 77 62 928.4 68 1361.0 1696.0
untitled Florida
Lemon Res, Durango, Nr 24.7 103 62 11.2 46 24.1 39.8
untitled
TOTAL 1183.2 81 64 1002.3 69 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