nLake Powell Water Supply Outlook, May 1, 2017

Lake Powell Water Supply Outlook, May 1, 2017

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-July395 415 430 176 455 470
May-July370 390 405 180 430 445
Pine Ck
Fremont Lk, Abv April-July133 140 148 151 154 165
May-July130 137 145 151 151 162
New Fork
Big Piney, Nr April-July605 660 690 194 725 785
May-July540 595 625 189 660 720
Green
Fontenelle Res, Fontenelle Nr April-July1460 1570 1680 232 1730 1840
May-July1230 1340 1450 227 1500 1610
Big Sandy
Farson, Nr April-July71 79 86 165 90 102
May-July67 75 82 171 86 98
Green
Green River, Wy, Nr April-July1480 1600 1730 237 1790 1900
May-July1240 1360 1490 233 1550 1660
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July100 107 113 209 123 131
May-July83 90 96 200 106 114
Viva Naughton Res April-July148 158 171 231 185 200
May-July111 121 134 216 148 164
Blacks Fork
Robertson, Nr April-July104 113 122 137 133 142
May-July94 103 112 132 123 132
Ef Smiths Fork
Stateline Res, Robertson,nr April-July31 33 37 142 40 45
May-July28 30 34 131 37 42
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July1950 2110 2260 231 2400 2490
May-July1600 1760 1910 226 2050 2140


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-July13.7 14.8 15.5 67 16 18
May-July10.2 11.3 12 75 12.5 14.5
Steamboat Springs April-July162 177 200 77 215 260
May-July136 151 175 80 187 235
Elk
Milner, Nr April-July265 290 320 100 345 395
May-July190 215 245 84 270 320
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July55 59 65 89 71 80
May-July28 32 38 76 44 53
Yampa
Maybell, Nr April-July645 700 770 82 840 965
May-July480 535 605 78 675 800
Little Snake
Slater, Nr April-July119 134 151 97 161 189
May-July90 105 122 88 132 160
Dixon, Nr April-July235 265 305 88 325 385
May-July175 205 245 83 265 325
Lily, Nr April-July240 275 320 93 345 405
May-July173 210 255 88 280 340
Yampa
Deerlodge Park April-July925 985 1080 87 1150 1320
May-July705 765 860 84 925 1100
White
Meeker, Nr April-July188 215 230 82 240 285
May-July150 177 191 78 200 245
Watson, Nr April-July198 225 245 88 255 310
May-July155 183 200 85 210 265


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-July21 21 23 110 25 29
May-July15.5 16.4 17.6 96 19.8 24
Ashley Ck
Vernal, Nr April-July50 53 58 116 62 74
May-July46 49 54 115 58 70
West Fork Duchesne
Vat Diversion, Blo April-July33 34 36 194 38 40
May-July31 32 34 197 36 38
Duchesne
Tabiona, Nr April-July170 178 188 174 195 205
May-July152 160 170 173 177 185
Rock Ck
Upper Stillwater Res April-July107 113 120 162 126 138
May-July99 105 112 158 118 130
South Fork Rock Ck
Docs Div, Blo April-July11.8 12.6 13 178 14.1 14.8
May-July10.8 11.6 12 174 13.1 13.8
Rock Ck
Mountain Home, Nr April-July130 136 146 166 152 167
May-July119 125 135 161 141 156
Currant Ck
Currant Ck Res April-July35 37 40 200 43 45
May-July30 32 35 205 38 40
Strawberry
Solider Springs,nr April-July100 106 115 162 123 130
May-July65 71 80 138 88 95
Starvation Res, Duchesne, Nr April-July210 220 230 205 245 255
May-July155 165 175 192 189 200
Duchesne
Duchesne, Nr, Knight Div, Abv April-July300 315 335 173 350 370
May-July270 285 305 170 320 340
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July89 93 101 153 106 120
May-July82 86 94 149 99 113
Yellowstone
Altonah, Nr April-July85 90 97 159 103 116
May-July78 83 90 158 96 109
Whiterocks
Whiterocks, Nr April-July69 73 80 148 84 98
May-July63 67 74 145 78 92
Uinta
Neola, Nr April-July101 108 117 158 123 141
May-July95 102 111 156 117 135
Duchesne
Myton April-July555 580 625 189 655 725
May-July470 495 540 183 570 640
Randlett, Nr April-July640 675 730 190 770 875
May-July540 575 630 183 670 775


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-July23 25 26 168 27 29
May-July14.2 15.7 17 143 18 20
Fish Ck
Scofield, Nr, Reservoir, Abv April-July45 47 49 163 52 55
May-July36 38 40 154 43 46
Price
Scofield Res, Scofield, Nr April-July63 67 69 168 73 78
May-July50 54 56 160 60 65
Green
Green River, Ut April-July3750 4120 4500 152 4820 5250
May-July3000 3370 3750 148 4070 4500
Huntington Ck
Electric Lake April-July24 25 26 195 28 31
May-July21 22 23 195 25 28
Power Plant, Blo April-July72 76 79 198 85 91
May-July65 69 72 195 78 84
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July67 72 75 134 78 90
May-July61 66 69 133 72 84
Ferron Ck
Ferron, Nr April-July50 53 56 147 59 66
May-July45 48 51 146 54 61
Muddy Ck
Emery, Nr April-July22 24 25 126 27 32
May-July19 21 22 122 24 29


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-July200 220 235 107 250 275
May-July174 194 210 102 225 250
Willow Ck
Willow Ck Res, Granby, Nr April-July50 58 65 138 75 80
May-July35 43 50 116 60 65
Fraser
Winter Park April-July17.5 19 21 108 23 26
May-July16.3 17.8 19.8 106 22 25
Williams Fork
Williams Fork Res, Parshall, Nr April-July90 97 105 109 110 125
May-July82 89 97 108 102 117
Muddy Ck
Wolford Mountain Reservoir April-July30 34 40 74 45 57
May-July20 24 30 65 35 47
Blue
Dillon Res April-July140 155 175 107 185 210
May-July125 140 160 105 170 195
Green Mtn Res April-July240 270 295 107 315 355
May-July210 240 265 104 285 325
Colorado
Kremmling, Nr April-July790 880 930 108 980 1100
May-July670 760 810 103 860 980
Eagle
Gypsum, Blo April-July240 265 300 90 330 390
May-July210 235 270 86 300 360
Colorado
Dotsero, Nr April-July1200 1320 1410 101 1500 1710
May-July1020 1140 1230 96 1320 1530
Frying Pan
Ruedi Res, Basalt, Nr April-July95 105 125 90 135 170
May-July83 93 113 87 123 158
Roaring Fork
Glenwood Springs April-July550 595 650 94 700 800
May-July490 535 590 92 640 740
Colorado
Glenwood Springs, Blo April-July1780 1950 2070 98 2200 2550
May-July1540 1710 1830 95 1960 2310
Cameo, Nr April-July1950 2100 2250 95 2400 2800
May-July1700 1850 2000 93 2150 2550
Plateau Ck
Cameo, Nr April-July60 70 95 77 110 135
May-July44 54 79 76 94 119
Colorado
Cisco, Nr April-July3850 4150 4500 101 4700 5500
May-July3150 3450 3800 98 4000 4800
Lake Powell, Glen Cyn Dam, At April-July7200 8300 8800 123 9500 11000
May-July5590 6690 7190 118 7890 9390


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-July98 105 111 112 118 133
May-July85 92 98 109 105 120
Almont April-July147 167 177 114 187 215
May-July125 145 155 110 165 195
East
Almont April-July215 225 240 132 250 280
May-July180 190 205 123 215 245
Gunnison
Gunnison, Nr April-July435 455 475 128 495 565
May-July360 380 400 119 420 490
Tomichi Ck
Gunnison April-July87 94 106 143 115 132
May-July60 67 79 127 88 105
Lake Fork
Gateview April-July107 122 130 106 138 163
May-July94 109 117 101 125 150
Gunnison
Blue Mesa Res April-July765 825 850 126 885 1020
May-July620 680 705 118 740 880
Morrow Point Res April-July835 895 920 124 955 1100
May-July680 740 765 118 800 940
Crystal Res April-July940 1000 1030 123 1060 1200
May-July775 835 860 117 895 1030
Muddy Ck
Paonia Res, Bardine, Nr March-June68 74 82 85 87 95
April-July62 68 76 78 81 89
May-June38 44 52 75 57 65
May-July42 48 56 75 61 69
Nf Gunnison
Somerset, Nr April-July225 235 255 86 275 310
May-July160 173 192 80 210 245
Surface Ck
Cedaredge April-July12.6 13.6 16 95 17.6 21
May-July9 10 12.4 88 14 17
Uncompahgre
Ridgway Res April-July81 91 102 101 108 124
May-July69 79 90 99 96 112
Colona April-July113 124 137 100 145 173
May-July95 106 119 99 127 155
Delta April-July82 96 112 99 121 152
May-July60 74 90 96 99 130
Gunnison
Grand Junction, Nr April-July1420 1570 1650 111 1740 1980
May-July1100 1250 1330 107 1420 1660


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-July255 275 295 120 315 340
May-July180 200 220 110 240 265
Mcphee Res April-July285 305 335 114 360 395
May-July189 210 240 109 265 300
San Miguel
Placerville, Nr April-July120 128 138 108 145 160
May-July100 108 118 104 125 140
Dolores
Cisco, Nr April-July530 565 605 107 645 710
May-July380 415 455 110 495 560


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-July200 215 225 105 235 255
May-July137 152 161 89 172 192
Carracas, Nr April-July350 370 395 104 415 450
May-July225 245 270 90 290 325
Navajo Res, Archuleta, Nr April-July585 660 695 95 725 820
May-July350 425 460 81 490 585
Farmington April-July965 1040 1100 100 1160 1330
May-July630 705 770 88 825 995
Bluff, Nr April-July950 1020 1100 100 1170 1380
May-July620 695 770 90 840 1050
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July47 53 56 104 58 65
May-July32 38 41 91 43 50
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July57 65 69 106 73 81
May-July38 46 50 93 54 62
Piedra
Arboles, Nr April-July184 197 210 100 220 245
May-July110 123 136 89 145 171
Los Pinos
Vallecito Res, Bayfield, Nr April-July170 193 205 106 210 250
May-July125 148 160 94 165 205
Animas
Durango April-July365 410 440 106 475 555
May-July285 330 360 99 395 475
Florida
Lemon Res, Durango, Nr April-July40 48 53 96 56 68
May-July30 38 43 88 46 58
La Plata
Hesperus April-July23 25 27 117 29 32
May-July16 18 20 110 22 25
Mancos
Mancos, Nr April-July33 36 39 126 42 45
May-July23 26 29 121 32 35

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 206.8 170 60 139.5 115 121.7 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 30.5 156 80 21.9 111 19.6 38.3
Blacks Fork
Meeks Cabin 15.8 118 53 9.5 71 13.4 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 7.4 135 54 6.6 120 5.5 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 3169.4 105 85 3165.0 105 3021.3 3749.0
untitled Strawberry
Solider Springs,nr 807.0 122 73 801.0 121 663.7 1105.9
Starvation Res, Duchesne, Nr 117.9 79 71 159.4 106 149.7 165.3
untitled Rock Ck
Upper Stillwater Res 2.3 51 7 2.1 48 4.5 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 30.1 111 83 24.6 90 27.3 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 20.2 106 79 17.4 92 19.0 25.7
untitled Price
Scofield Res, Scofield, Nr 21.7 70 33 13.8 45 30.9 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 32.7 82 52 37.2 93 40.0 62.5
untitled Huntington Ck
Electric Lake 16.5 90 52 16.6 91 18.3 31.5
untitled
TOTAL 4478.4 108 79 4414.6 107 4134.9 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 392.3 126 80 380.6 122 311.8 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.0 104 88 7.8 101 7.7 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 74.8 123 77 76.7 126 60.9 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 60.5 127 92 47.0 99 47.7 66.0
untitled Blue
Dillon Res 215.5 101 85 239.3 112 213.6 254.0
Green Mtn Res 69.5 109 47 67.0 105 63.9 146.9
untitled Homestake Ck
Homestake Res 23.7 126 55 41.4 220 18.8 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 68.8 110 67 70.1 112 62.6 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 20.6 112 63 18.2 99 18.3 32.9
untitled Taylor
Taylor Park Res 73.2 120 69 71.0 116 61.2 106.2
untitled Gunnison
Blue Mesa Res 657.6 144 79 570.7 125 457.1 829.5
Morrow Point Res 108.8 97 93 111.1 99 111.8 117.0
Crystal Res 16.6 99 94 16.5 99 16.7 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 2.3 36 14 3.3 51 6.4 16.7
untitled Uncompahgre
Ridgway Res 62.9 94 76 68.0 102 66.6 83.0
untitled Dolores
Mcphee Res 353.2 109 93 297.7 92 323.0 381.1
untitled
TOTAL 2208.4 119 79 2086.4 113 1848.0 2792.1
Colorado
Lake Powell 12149.5 71 50 11013.5 64 17122.8 24322.0
untitled
TOTAL 12149.5 71 50 11013.5 64 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 86.5 117 69 104.9 142 74.0 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 1597.7 117 94 1491.0 110 1361.0 1696.0
untitled Florida
Lemon Res, Durango, Nr 26.5 110 67 27.5 114 24.1 39.8
untitled
TOTAL 1710.7 117 92 1623.4 111 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