Lake Powell Water Supply Outlook, May 1, 2013

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




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Yampa/White Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Duchesne Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Lower Green Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Upper Colorado Mainstem Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Gunnison Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Dolores Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

San Juan Basin Conditions




* 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-July126 171 70 200
May-July115 160 71 190
Pine Ck
Fremont Lk, Abv April-July47 62 63 82
May-July46 61 64 81
New Fork
Big Piney, Nr April-July102 173 49 270
May-July94 165 50 260
Green
Fontenelle Res, Fontenelle Nr April-July240 380 52 505
May-July190 330 52 455
Big Sandy
Farson, Nr April-July17.6 30 58 45
May-July15 27 56 42
Green
Green River, Wy, Nr April-July225 365 50 500
May-July175 315 49 450
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July22 33 61 42
May-July18 29 60 38
Viva Naughton Res April-July23 39 53 58
May-July15 31 50 50
Blacks Fork
Robertson, Nr April-July42 63 71 82
May-July40 61 72 80
Ef Smiths Fork
Stateline Res, Robertson,nr April-July13.6 18.4 71 25
May-July13 17.8 68 24
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July300 480 49 685
May-July230 410 49 610


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-July12.3 18.1 79 25
May-July7 12.8 80 20
Steamboat Springs April-July152 196 75 245
May-July135 179 81 230
Elk
Milner, Nr April-July185 240 75 305
May-July166 220 76 285
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July28 42 58 58
May-July20 34 68 50
Yampa
Maybell, Nr April-July450 605 65 770
May-July380 535 69 700
Little Snake
Slater, Nr April-July61 93 60 126
May-July55 87 63 120
Savery, Nr April-July97 169 49 245
May-July83 155 53 230
Lily, Nr April-July96 173 50 250
May-July80 157 54 235
White
Meeker, Nr April-July134 176 63 230
May-July110 152 62 205
Watson, Nr April-July121 176 63 235
May-July100 155 66 210


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-July12.1 14.2 68 18.6
May-July11.3 13.4 73 17.8
Ashley Ck
Vernal, Nr April-July24 33 66 43
May-July22 31 66 41
West Fork Duchesne
Vat Diversion, Blo April-July7 11.1 60 15.5
May-July6.4 10.5 61 14.9
Duchesne
Tabiona, Nr April-July53 72 67 92
May-July46 65 66 85
Rock Ck
Upper Stillwater Res April-July43 56 76 70
May-July41 54 76 68
South Fork Rock Ck
Docs Div, Blo April-July4.2 5.2 71 6.6
May-July3.9 4.9 71 6.3
Rock Ck
Mountain Home, Nr April-July55 67 76 83
May-July52 64 76 80
Currant Ck
Currant Ck Res April-July7.1 8.7 44 13
May-July5.8 7.4 43 11.7
Strawberry
Solider Springs,nr April-July11.9 18.9 34 29
May-July6.1 13.1 30 23
Starvation Res, Duchesne, Nr April-July26 40 36 60
May-July16 30 33 50
Duchesne
Duchesne, Nr, Knight Div, Abv April-July105 136 70 170
May-July94 125 70 159
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July36 50 76 65
May-July34 48 76 63
Yellowstone
Altonah, Nr April-July33 45 74 56
May-July30 42 74 53
Whiterocks
Whiterocks, Nr April-July25 39 72 52
May-July23 37 73 50
Uinta
Neola, Nr April-July33 52 70 72
May-July31 50 70 70
Duchesne
Myton April-July97 149 45 205
May-July73 125 42 181
Randlett, Nr April-July108 160 42 215
May-July83 135 39 192


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-July2.2 3.9 25 6.4
May-July1.5 3.2 27 5.7
Fish Ck
Scofield, Nr, Reservoir, Abv April-July14.3 17 57 22
May-July12.1 14.8 57 19.6
Price
Scofield Res, Scofield, Nr April-July17.9 22 54 29
May-July15.2 19 54 26
Green
Green River, Ut April-July1150 1540 52 2170
May-July975 1370 54 2000
Huntington Ck
Electric Lake April-July3.5 5.3 40 7.2
May-July2.7 4.5 38 6.4
Power Plant, Blo April-July17.3 19.7 49 26
May-July16 18.4 50 25
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July18.8 25 45 33
May-July17 23 44 31
Ferron Ck
Ferron, Nr April-July13.7 19.5 51 28
May-July12.8 18.6 53 27
Muddy Ck
Emery, Nr April-July7.7 9.3 47 11.6
May-July7.1 8.7 48 11


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-July145 180 82 215
May-July135 170 83 205
Willow Ck
Willow Ck Res, Granby, Nr April-July36 49 104 60
May-July33 46 107 57
Fraser
Winter Park April-July10.7 14.7 76 19.2
May-July10 14 75 18.5
Williams Fork
Williams Fork Res, Parshall, Nr April-July59 73 76 94
May-July54 68 76 89
Muddy Ck
Wolford Mountain Reservoir April-July33 44 81 60
May-July29 40 87 56
Blue
Dillon Res April-July98 123 75 151
May-July92 117 76 145
Green Mtn Res April-July158 205 75 265
May-July145 190 75 250
Colorado
Kremmling, Nr April-July545 660 77 850
May-July495 610 78 800
Eagle
Gypsum, Blo April-July136 190 57 265
May-July125 179 57 255
Colorado
Dotsero, Nr April-July795 990 71 1280
May-July715 910 71 1200
Frying Pan
Ruedi Res, Basalt, Nr April-July59 80 58 114
May-July55 76 58 110
Roaring Fork
Glenwood Springs April-July300 395 57 525
May-July275 370 58 500
Colorado
Glenwood Springs, Blo April-July1140 1420 67 1840
May-July1030 1310 68 1730
Cameo, Nr April-July1170 1530 65 2010
May-July1060 1420 66 1900
Plateau Ck
Cameo, Nr April-July38 65 52 99
May-July27 54 52 88
Colorado
Cisco, Nr April-July1810 2310 52 3070
May-July1570 2070 54 2830
Lake Powell, Glen Cyn Dam, At April-July1750 3000 42 4250
May-July1400 2650 43 3900


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-July49 65 66 79
May-July43 59 66 73
Almont April-July73 90 58 113
May-July65 82 58 105
East
Almont April-July83 102 56 128
May-July75 94 57 120
Gunnison
Gunnison, Nr April-July171 196 53 240
May-July155 180 54 225
Tomichi Ck
Gunnison April-July18 26 35 45
May-July16 24 39 43
Lake Fork
Gateview April-July40 57 46 77
May-July38 55 47 75
Gunnison
Blue Mesa Res April-July275 335 50 425
May-July230 290 48 380
Morrow Point Res April-July300 360 49 450
May-July250 310 48 400
Crystal Res April-July335 395 47 485
May-July280 340 46 430
Muddy Ck
Paonia Res, Bardine, Nr March-June35 42 44 53
April-July35 42 43 53
May-June27 34 49 45
May-July29 36 48 47
Nf Gunnison
Somerset, Nr April-July144 169 57 220
May-July125 150 63 200
Surface Ck
Cedaredge April-July5 7 42 11
May-July4 6 43 10
Uncompahgre
Ridgway Res April-July38 50 50 63
May-July30 42 46 55
Colona April-July41 54 39 74
May-July32 45 38 65
Delta April-July19 30 27 58
May-July11 22 23 50
Gunnison
Grand Junction, Nr April-July490 640 43 880
May-July390 540 44 780


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-July72 102 42 132
May-July55 85 43 115
Mcphee Res April-July84 107 36 147
May-July67 90 41 130
San Miguel
Placerville, Nr April-July47 60 47 79
May-July40 53 47 72
Dolores
Cisco, Nr April-July124 149 26 210
May-July95 120 29 180


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-July81 106 49 122
May-July60 85 47 101
Carracas, Nr April-July138 165 43 193
May-July115 142 47 170
Navajo Res, Archuleta, Nr April-July265 325 44 420
May-July195 255 45 350
Farmington April-July340 430 39 565
May-July260 350 40 485
Bluff, Nr April-July275 385 35 525
May-July200 310 36 450
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July20 26 48 33
May-July15 21 47 28
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July23 28 43 37
May-July18 23 43 32
Piedra
Arboles, Nr April-July86 106 50 131
May-July60 80 52 105
Los Pinos
Vallecito Res, Bayfield, Nr April-July78 98 51 125
May-July63 83 49 110
Animas
Durango April-July160 210 51 290
May-July140 190 52 270
Florida
Lemon Res, Durango, Nr April-July17 25 45 35
May-July14 22 45 32
La Plata
Hesperus April-July6.7 8.7 38 12.7
May-July5 7 38 11
Mancos
Mancos, Nr April-July7 11 35 14
May-July6 10 42 13

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 128.1 102 37 160.1 128 125.0 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 11.2 53 29 30.0 141 21.3 38.3
Blacks Fork
Meeks Cabin 10.1 62 34 29.5 179 16.5 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 5.2 80 38 10.4 160 6.5 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 3001.9 99 80 3205.1 105 3040.4 3749.0
untitled Strawberry
Solider Springs,nr 899.9 120 81 993.6 132 752.8 1105.9
Starvation Res, Duchesne, Nr 164.7 108 100 163.6 108 151.9 165.3
untitled Rock Ck
Upper Stillwater Res 6.5 226 21 2.9 102 2.9 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 13.7 50 38 28.0 101 27.6 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 15.0 75 58 24.7 123 20.1 25.7
untitled Price
Scofield Res, Scofield, Nr 32.3 98 49 54.6 165 33.0 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 33.7 85 54 52.4 132 39.6 62.5
untitled Huntington Ck
Electric Lake 19.3 103 61 24.9 133 18.7 31.5
untitled
TOTAL 4341.8 102 76 4779.9 112 4256.3 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 182.2 58 37 420.6 135 311.8 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.1 106 89 7.8 101 7.7 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 45.0 74 46 86.7 142 60.9 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 26.9 56 41 66.5 139 47.7 66.0
untitled Blue
Dillon Res 161.5 76 64 239.6 112 213.6 254.0
Green Mtn Res 65.8 103 45 88.9 139 63.9 146.9
untitled Homestake Ck
Homestake Res -9999.0 -99 -99 0.3 2 18.8 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 62.6 100 61 77.4 124 62.6 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 11.2 61 34 28.7 156 18.3 32.9
untitled Taylor
Taylor Park Res 59.2 97 56 72.8 119 61.2 106.2
untitled Gunnison
Blue Mesa Res 338.0 74 41 532.1 116 457.1 829.5
Morrow Point Res 106.5 95 91 114.7 103 111.8 117.0
Crystal Res 12.9 77 74 16.7 100 16.7 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 7.2 111 43 12.5 195 6.4 16.7
untitled Uncompahgre
Ridgway Res 60.4 91 73 74.2 111 66.6 83.0
untitled Dolores
Mcphee Res 197.9 61 52 340.9 106 323.0 381.1
untitled
TOTAL 1345.6 74 49 2180.4 118 1829.2 2749.1
Colorado
Lake Powell 11422.0 67 47 15508.0 91 17122.8 24322.0
untitled
TOTAL 11422.0 67 47 15508.0 91 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 62.7 85 50 116.8 158 74.0 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 928.4 68 55 1346.3 99 1361.0 1696.0
untitled Florida
Lemon Res, Durango, Nr 11.2 46 28 27.3 113 24.1 39.8
untitled
TOTAL 1002.3 69 54 1490.4 102 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