Lake Powell Water Supply Outlook, June 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-July173 183 205 84 215 245
June-July120 130 152 90 161 192
Pine Ck
Fremont Lk, Abv April-July84 91 95 97 100 110
June-July70 77 81 107 86 96
New Fork
Big Piney, Nr April-July315 330 360 101 410 435
June-July220 235 265 104 315 340
Green
Fontenelle Reservoir, Fontenelle, Nr April-July690 735 780 108 835 910
June-July410 455 500 105 555 630
Big Sandy
Farson, Nr April-July45 49 55 106 60 66
June-July28 32 38 112 43 49
Green
Green River, Wy, Nr April-July690 730 775 106 835 925
June-July420 460 505 105 565 655
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July40 44 47 87 50 59
June-July19 23 26 100 29 38
Viva Naughton Reservoir April-July55 59 64 86 67 78
June-July22 26 31 100 34 45
Blacks Fork
Robertson, Nr April-July91 97 103 116 105 116
June-July66 72 78 132 80 91
Ef Smiths Fork
Stateline Reservoir, Robertson,nr April-July31 32 34 131 36 38
June-July22 23 25 140 27 29
Green
Flaming Gorge Reservoir April-July1020 1090 1170 119 1230 1360
June-July530 595 675 113 735 870


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-July21 21 23 100 24 28
June-July5.3 6.1 8 93 9.1 12.5
Steamboat Springs April-July255 265 275 106 280 315
June-July135 144 155 130 159 195
Elk
Milner, Nr April-July380 395 405 127 410 450
June-July186 205 215 135 220 260
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July76 78 81 111 83 89
June-July10.5 12.8 16 154 18.1 24
Yampa
Maybell, Nr April-July960 1000 1040 111 1060 1170
June-July430 470 510 131 530 640
Little Snake
Slater, Nr April-July145 151 164 105 171 192
June-July60 66 79 120 86 107
Dixon, Nr April-July325 345 365 106 375 405
June-July130 149 170 126 181 210
Lily, Nr April-July340 355 370 107 385 415
June-July138 152 170 127 183 215
Yampa
Deerlodge Park April-July1340 1390 1450 117 1480 1610
June-July600 655 710 142 740 870
White
Meeker, Nr April-July260 270 285 102 295 325
June-July146 156 175 122 181 215
Watson, Nr April-July275 290 310 111 310 340
June-July162 173 193 139 197 225


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-July19.9 21 22 105 23 26
June-July10 11.3 12 133 12.8 16.2
Ashley Ck
Vernal, Nr April-July56 60 63 126 65 74
June-July33 37 40 167 42 51
West Fork Duchesne
Vat Diversion, Blo April-July29 30 31 167 33 34
June-July21 22 23 247 25 26
Duchesne
Tabiona, Nr April-July142 148 157 145 161 170
June-July95 101 110 183 114 123
Rock Ck
Upper Stillwater Reservoir April-July106 110 114 154 117 124
June-July84 88 92 196 95 102
South Fork Rock Ck
Docs Div, Blo April-July11.5 12.1 12.3 168 12.9 13.5
June-July9.7 10.3 10.5 214 11.1 11.7
Rock Ck
Mountain Home, Nr April-July129 132 137 156 140 147
June-July102 105 110 196 113 120
Currant Ck
Currant Ck Reservoir April-July26 27 29 145 31 34
June-July13 13.8 16 216 18 21
Strawberry
Strawberry Reservoir, Soldier Springs April-July119 120 128 180 131 138
June-July35 36 44 183 47 54
Starvation Reservoir, Duchesne, Nr April-July210 215 225 201 235 250
June-July80 86 95 250 106 117
Duchesne
Duchesne, Nr, Knight Div, Abv April-July270 280 290 149 295 315
June-July196 205 215 187 220 240
Lake Fork
Moon Lake Reservoir, Mtn Home, Nr April-July93 98 102 155 103 111
June-July77 82 86 200 87 95
Yellowstone
Altonah, Nr April-July91 97 100 164 102 112
June-July75 81 84 205 86 96
Whiterocks
Whiterocks, Nr April-July62 68 70 130 74 82
June-July50 56 58 171 62 70
Uinta
Neola, Nr April-July108 114 120 162 128 137
June-July94 100 106 212 114 123
Duchesne
Myton April-July565 580 610 185 630 680
June-July360 375 405 234 425 475
Randlett, Nr April-July645 675 730 190 750 815
June-July430 460 515 245 535 600


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-July24 25 26 168 27 28
June-July5.1 5.8 6.8 200 7.7 9
Fish Ck
Scofield, Nr, Reservoir, Abv April-July54 57 60 200 62 68
June-July30 33 36 371 38 44
Price
Scofield Reservoir, Scofield, Nr April-July79 85 89 217 92 99
June-July44 50 54 403 57 64
Green
Green River, Ut April-July3410 3600 3810 129 3970 4320
June-July1850 2040 2250 145 2410 2760
Huntington Ck
Electric Lake April-July27 29 30 226 31 34
June-July19 21 22 458 23 26
Power Plant, Blo April-July77 81 84 210 88 96
June-July57 61 64 323 68 76
Seeley Ck
Joes Vly Reservoir, Orangeville, Nr April-July85 89 94 168 95 105
June-July65 69 74 231 75 85
Ferron Ck
Ferron, Nr April-July65 70 72 189 75 81
June-July49 54 56 267 59 65
Muddy Ck
Emery, Nr April-July29 32 33 166 34 38
June-July22 25 26 222 27 31


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-July220 230 245 111 260 275
June-July169 179 194 134 210 225
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July62 65 69 147 73 77
June-July30 33 37 176 41 45
Fraser
Winter Park April-July17 18.4 19.7 102 21 23
June-July14 15.4 16.7 118 18 20
Williams Fork
Williams Fork Reservoir, Parshall April-July93 99 105 109 111 118
June-July66 72 78 120 84 91
Muddy Ck
Wolford Mountain Reservoir April-July60 63 66 122 70 74
June-July27 30 33 171 37 41
Blue
Dillon Reservoir April-July210 220 230 141 240 255
June-July171 181 191 174 200 215
Green Mtn Reservoir April-July330 345 360 131 380 400
June-July255 270 285 155 305 325
Colorado
Kremmling, Nr April-July980 1020 1070 124 1130 1190
June-July670 710 760 145 820 880
Eagle
Gypsum, Blo April-July410 430 450 134 475 500
June-July310 330 350 163 375 400
Colorado
Dotsero, Nr April-July1620 1680 1750 125 1840 1920
June-July1130 1190 1260 150 1350 1430
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July160 167 175 126 183 190
June-July125 132 140 157 148 155
Roaring Fork
Glenwood Springs April-July815 850 880 128 920 955
June-July620 655 685 151 725 760
Colorado
Glenwood Springs, Blo April-July2400 2550 2700 128 2860 3000
June-July1680 1830 1980 152 2140 2280
Cameo, Nr April-July2750 2880 3000 127 3150 3300
June-July1950 2080 2200 155 2350 2500
Plateau Ck
Cameo, Nr April-July170 178 185 149 195 205
June-July105 113 120 245 130 140
Colorado
Cisco, Nr April-July5850 6050 6250 141 6500 6700
June-July3690 3890 4090 175 4340 4540
Lake Powell, Glen Cyn Dam, At April-July9450 9910 10300 144 10650 11250
June-July5700 6160 6550 174 6900 7500


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 Reservoir April-July128 131 140 141 145 152
June-July97 100 109 176 114 121
Almont April-July200 205 215 139 220 230
June-July147 153 162 172 168 177
East
Almont April-July235 240 250 137 260 270
May-July0 0 0 0 0 0
June-July165 170 180 170 189 200
Gunnison
Gunnison, Nr April-July495 505 520 141 535 550
June-July345 355 370 172 385 400
Tomichi Ck
Gunnison April-July130 135 140 189 148 156
June-July70 75 80 216 88 96
Lake Fork
Gateview April-July177 184 190 154 199 215
June-July140 147 153 189 162 178
Gunnison
Blue Mesa Reservoir April-July1010 1020 1040 154 1070 1120
June-July670 685 705 186 730 780
Morrow Point Reservoir April-July1110 1120 1140 154 1170 1220
June-July730 745 765 189 790 840
Crystal Reservoir April-July1250 1260 1280 153 1310 1360
June-July830 845 865 192 890 940
Muddy Ck
Paonia Reservoir, Bardine, Nr March-June129 132 135 141 138 140
April-July136 139 143 147 145 150
June-June47 50 53 230 56 58
June-July58 61 64 221 67 69
Nf Gunnison
Somerset, Nr April-July375 385 390 132 395 405
June-July205 215 220 193 225 235
Surface Ck
Cedaredge April-July28 29 31 185 33 35
June-July19 20 22 289 24 26
Uncompahgre
Ridgway Reservoir April-July121 125 128 127 133 140
June-July94 98 101 155 106 113
Colona April-July155 161 168 123 175 185
June-July119 125 132 163 139 149
Delta April-July154 161 170 150 177 185
June-July94 101 110 193 117 125
Gunnison
Grand Junction, Nr April-July2120 2160 2190 148 2250 2330
June-July1290 1330 1360 196 1420 1500


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-July320 330 340 139 350 360
June-July176 186 196 213 205 215
Mcphee Reservoir April-July405 415 425 144 435 450
June-July184 194 205 211 215 230
San Miguel
Placerville, Nr April-July153 160 165 129 171 178
June-July100 107 112 149 118 125
Dolores
Cisco, Nr April-July840 855 870 154 890 920
June-July370 385 400 217 420 450


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-July280 290 295 137 305 315
June-July145 155 160 167 170 180
Carracas, Nr April-July465 480 490 129 500 530
June-July225 240 250 158 260 290
Navajo Reservoir, Archuleta, Nr April-July950 985 1000 136 1040 1110
June-July450 485 500 172 540 610
Farmington April-July1520 1550 1570 143 1640 1700
June-July830 855 875 186 950 1010
Bluff, Nr April-July1550 1580 1600 145 1680 1730
June-July820 845 870 193 950 1000
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July66 68 71 131 74 77
June-July37 39 42 183 45 48
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July73 77 80 123 83 88
June-July40 44 47 157 50 55
Piedra
Arboles, Nr April-July280 290 295 140 305 320
June-July115 125 130 176 140 155
Los Pinos
Vallecito Reservoir, Bayfield, Nr April-July260 270 275 142 290 310
June-July169 179 184 186 197 220
Animas
Durango April-July555 590 605 146 625 660
June-July355 390 405 184 425 460
Florida
Lemon Reservoir, Durango, Nr April-July64 67 70 127 74 78
June-July46 49 52 193 56 60
La Plata
Hesperus April-July30 32 33 143 35 37
June-July17 19 20 235 22 24
Mancos
Mancos, Nr April-July34 36 38 123 39 42
June-July12 14 16 154 17 20

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 Reservoir, Fontenelle, Nr 204.1 124 59 260.4 159 164.0 344.8
untitled Big Sandy
Big Sandy Reservoir, Nr Farson 29.2 99 76 38.5 131 29.4 38.3
Blacks Fork
Meeks Cabin 22.5 90 75 30.2 121 24.9 29.9
untitled Ef Smiths Fork
Stateline Reservoir, Robertson,nr 9.4 83 68 14.0 124 11.3 13.9
untitled Green
Flaming Gorge Reservoir 3376.5 110 90 3294.2 107 3071.5 3749.0
untitled Strawberry
Strawberry Reservoir, Soldier Springs 966.2 135 87 949.2 133 716.0 1105.9
Starvation Reservoir, Duchesne, Nr 154.7 100 94 155.2 100 154.8 165.3
untitled Rock Ck
Upper Stillwater Reservoir 6.3 40 20 19.0 121 15.7 31.4
untitled Lake Fork
Moon Lake Reservoir, Mtn Home, Nr 13.7 48 37 36.0 126 28.6 36.5
untitled Big Brush Ck
Red Fleet Reservoir, Vernal, Nr 19.9 85 77 19.9 85 23.4 25.7
untitled Price
Scofield Reservoir, Scofield, Nr 44.3 91 67 51.4 106 48.5 65.8
untitled Seeley Ck
Joes Vly Reservoir, Orangeville, Nr 27.6 53 44 51.6 100 51.6 62.5
untitled Huntington Ck
Electric Lake 20.1 84 64 23.5 99 23.8 31.5
untitled
TOTAL 4894.4 112 86 4943.0 113 4363.6 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 375.7 103 77 489.9 135 363.6 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 8.1 91 89 9.4 106 8.9 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 79.9 109 82 88.1 121 73.0 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 57.2 95 87 66.8 111 59.9 66.0
untitled Blue
Dillon Reservoir 186.4 80 73 257.0 110 232.7 254.0
Green Mtn Reservoir 85.4 95 58 95.9 107 89.8 146.9
untitled Homestake Ck
Homestake Reservoir 13.2 53 31 35.4 143 24.8 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 66.1 85 65 81.2 104 78.0 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 24.1 78 73 24.9 81 30.8 32.9
untitled Taylor
Taylor Park Reservoir 58.8 79 55 83.9 112 74.7 106.2
untitled Gunnison
Blue Mesa Reservoir 447.2 78 54 512.6 89 575.3 829.5
Morrow Point Reservoir 112.8 100 96 112.0 99 113.2 117.0
Crystal Reservoir 18.9 113 108 15.9 95 16.7 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 6.8 43 41 15.6 100 15.7 16.7
untitled Uncompahgre
Ridgway Reservoir 59.1 84 71 64.4 91 70.7 83.0
untitled Dolores
Mcphee Reservoir 333.7 96 88 257.2 74 347.8 381.1
untitled
TOTAL 1933.4 89 69 2210.3 102 2175.6 2792.1
Colorado
Lake Powell 10343.1 57 43 12885.9 71 18186.3 24322.0
untitled
TOTAL 10343.1 57 43 12885.9 71 18186.3 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 Reservoir, Bayfield, Nr 64.5 64 51 84.4 84 100.5 125.4
untitled San Juan
Navajo Reservoir, Archuleta, Nr 1278.8 89 75 1223.2 86 1429.7 1696.0
untitled Florida
Lemon Reservoir, Durango, Nr 18.9 59 47 18.5 58 32.1 39.8
untitled
TOTAL 1362.1 87 73 1326.1 85 1562.3 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