Lake Powell Water Supply Outlook, March 1, 2018

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-July250 290 310 127 335 380
Pine Ck
Fremont Lk, Abv April-July78 87 100 102 104 118
New Fork
Big Piney, Nr April-July260 300 355 100 405 475
Green
Fontenelle Res, Fontenelle Nr April-July620 730 840 116 955 1120
Big Sandy
Farson, Nr April-July36 44 50 96 56 70
Green
Green River, Wy, Nr April-July655 790 845 116 985 1150
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July25 30 36 67 45 58
Viva Naughton Res April-July31 38 45 61 56 79
Blacks Fork
Robertson, Nr April-July46 56 65 73 79 100
Ef Smiths Fork
Stateline Res, Robertson,nr April-July15.1 18.8 21 81 24 29
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July700 850 940 96 1090 1420


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-July9 12.8 14.5 63 15.2 18.2
Steamboat Springs April-July110 148 174 67 199 250
Elk
Milner, Nr April-July165 215 245 77 275 330
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July23 31 41 56 47 60
Yampa
Maybell, Nr April-July365 480 595 64 680 850
Little Snake
Slater, Nr April-July63 82 100 64 117 152
Dixon, Nr April-July118 163 190 55 230 315
Lily, Nr April-July115 162 195 57 240 320
Yampa
Deerlodge Park April-July465 645 790 64 905 1150
White
Meeker, Nr April-July115 138 155 55 177 230
Watson, Nr April-July117 141 158 56 184 245


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-July7.5 10.5 12.9 61 14.4 20
Ashley Ck
Vernal, Nr April-July16.7 21 27 54 31 46
West Fork Duchesne
Vat Diversion, Blo April-July4.1 6.2 7.5 40 10 12.6
Duchesne
Tabiona, Nr April-July45 53 60 56 70 82
Rock Ck
Upper Stillwater Res April-July32 39 47 64 56 64
South Fork Rock Ck
Docs Div, Blo April-July1.7 2.4 3.2 44 3.8 4.8
Rock Ck
Mountain Home, Nr April-July37 46 56 64 67 77
Currant Ck
Currant Ck Res April-July4.2 4.6 6 30 8.5 12
Strawberry
Solider Springs,nr April-July11 15.8 20 28 25 37
Starvation Res, Duchesne, Nr April-July25 32 38 34 48 65
Duchesne
Duchesne, Nr, Knight Div, Abv April-July80 98 114 59 133 149
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July21 29 38 58 42 54
Yellowstone
Altonah, Nr April-July25 34 39 64 46 55
Whiterocks
Whiterocks, Nr April-July18.4 23 30 56 35 46
Uinta
Neola, Nr April-July26 37 48 65 55 69
Duchesne
Myton April-July67 99 130 39 163 215
Randlett, Nr April-July74 104 133 35 164 230


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-July1.7 3.1 3.9 25 6 8.5
Fish Ck
Scofield, Nr, Reservoir, Abv April-July6.6 8 10.7 36 12.8 19.5
Price
Scofield Res, Scofield, Nr April-July8.9 10.8 14 34 16.8 26
Green
Green River, Ut April-July1450 1710 1920 65 2300 2860
Huntington Ck
Electric Lake April-July3.2 3.7 4.3 32 4.9 7.8
Power Plant, Blo April-July15.4 16.3 17.4 44 18.3 25
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July16.9 22 24 43 29 40
Ferron Ck
Ferron, Nr April-July10.8 16 20 53 24 35
Muddy Ck
Emery, Nr April-July4.6 6.2 7.5 38 8.1 11.1


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-July130 158 190 86 215 270
Willow Ck
Willow Ck Res, Granby, Nr April-July24 30 40 85 50 67
Fraser
Winter Park April-July14 16 18 93 20 23
Williams Fork
Williams Fork Res, Parshall, Nr April-July60 72 80 83 88 113
Muddy Ck
Wolford Mountain Reservoir April-July21 28 36 67 44 58
Blue
Dillon Res April-July105 125 145 89 160 180
Green Mtn Res April-July170 200 235 85 260 305
Colorado
Kremmling, Nr April-July520 620 705 82 800 1020
Eagle
Gypsum, Blo April-July160 195 220 66 245 330
Colorado
Dotsero, Nr April-July780 920 1060 76 1200 1530
Frying Pan
Ruedi Res, Basalt, Nr April-July66 82 94 68 105 136
Roaring Fork
Glenwood Springs April-July350 415 460 67 500 645
Colorado
Glenwood Springs, Blo April-July1170 1360 1530 73 1690 2230
Cameo, Nr April-July1250 1430 1630 69 1800 2400
Plateau Ck
Cameo, Nr April-July23 35 45 36 58 85
Colorado
Cisco, Nr April-July1850 2150 2520 57 2900 3760
Lake Powell, Glen Cyn Dam, At April-July2200 2700 3400 47 4200 5700


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-July55 63 70 71 76 90
Almont April-July85 96 104 67 116 140
East
Almont April-July70 98 112 62 125 160
Gunnison
Gunnison, Nr April-July145 180 225 61 260 320
Tomichi Ck
Gunnison April-July22 28 36 49 50 65
Lake Fork
Gateview April-July49 65 78 63 93 117
Gunnison
Blue Mesa Res April-July250 300 395 59 450 575
Morrow Point Res April-July285 335 430 58 485 610
Crystal Res April-July330 480 475 57 530 655
Muddy Ck
Paonia Res, Bardine, Nr March-June23 29 37 39 50 65
April-July22 28 36 37 49 64
Nf Gunnison
Somerset, Nr April-July95 117 142 48 170 220
Surface Ck
Cedaredge April-July3 3.5 4.5 27 7 10
Uncompahgre
Ridgway Res April-July39 48 59 58 75 90
Colona April-July40 55 65 47 85 110
Delta April-July21 29 38 34 55 83
Gunnison
Grand Junction, Nr April-July530 650 725 49 900 1140


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-July63 91 107 44 130 175
Mcphee Res April-July65 85 113 38 133 195
San Miguel
Placerville, Nr April-July40 50 64 50 80 98
Dolores
Cisco, Nr April-July100 135 185 33 235 325


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-July65 95 112 52 135 165
Carracas, Nr April-July120 160 190 50 230 265
Navajo Res, Archuleta, Nr April-July150 220 285 39 370 470
Farmington April-July225 310 385 35 480 610
Bluff, Nr April-July190 280 355 32 410 565
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July20 26 34 63 42 50
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July23 29 37 57 44 51
Piedra
Arboles, Nr April-July50 64 82 39 110 142
Los Pinos
Vallecito Res, Bayfield, Nr April-July42 60 80 41 95 121
Animas
Durango April-July95 130 165 40 190 240
Florida
Lemon Res, Durango, Nr April-July8 13 18 33 23 31
La Plata
Hesperus April-July3.5 5 7 30 9 13
Mancos
Mancos, Nr April-July5 7.5 9.5 31 12 18

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 130.9 103 38 177.6 139 127.6 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 31.6 210 83 24.7 164 15.1 38.3
Blacks Fork
Meeks Cabin 11.1 90 37 12.5 101 12.3 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 6.1 114 44 6.6 123 5.4 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 3194.0 106 85 3088.1 102 3015.6 3749.0
untitled Strawberry
Solider Springs,nr 932.0 141 84 784.2 119 660.2 1105.9
Starvation Res, Duchesne, Nr 165.3 114 100 129.4 90 144.5 165.3
untitled Rock Ck
Upper Stillwater Res 9.2 120 29 12.7 166 7.6 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 25.6 96 70 26.6 100 26.6 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 20.3 110 79 21.3 115 18.5 25.7
untitled Price
Scofield Res, Scofield, Nr 51.4 168 78 16.6 54 30.6 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 45.6 113 73 31.0 77 40.2 62.5
untitled Huntington Ck
Electric Lake 23.9 127 76 16.1 86 18.8 31.5
untitled
TOTAL 4646.9 113 82 4347.3 105 4123.0 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 463.8 140 95 398.0 120 332.0 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.2 99 90 8.6 105 8.2 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 66.3 106 68 73.2 117 62.4 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 54.2 123 82 50.5 114 44.2 66.0
untitled Blue
Dillon Res 238.9 109 94 218.5 100 219.3 254.0
Green Mtn Res 68.3 93 47 65.7 89 73.5 146.9
untitled Homestake Ck
Homestake Res -9999.0 -99 -99 42.1 137 30.7 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 67.1 99 66 66.1 97 67.9 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 11.6 88 35 12.7 96 13.2 32.9
untitled Taylor
Taylor Park Res 72.3 110 68 69.0 105 65.7 106.2
untitled Gunnison
Blue Mesa Res 547.1 113 66 571.4 118 482.2 829.5
Morrow Point Res 108.4 98 93 101.9 92 111.1 117.0
Crystal Res 16.1 102 92 16.0 101 15.8 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 3.6 78 22 2.5 53 4.7 16.7
untitled Uncompahgre
Ridgway Res 61.6 89 74 65.0 94 69.4 83.0
untitled Dolores
Mcphee Res 284.1 104 75 298.7 110 272.3 381.1
untitled
TOTAL 2071.8 112 75 2059.8 110 1842.0 2749.1
Colorado
Lake Powell 13345.8 78 55 11217.0 66 17054.6 24322.0
untitled
TOTAL 13345.8 78 55 11217.0 66 17054.6 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 69.8 110 56 76.2 120 63.5 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 1246.0 96 73 1339.1 104 1292.2 1696.0
untitled Florida
Lemon Res, Durango, Nr 18.7 89 47 21.0 100 21.0 39.8
untitled
TOTAL 1334.5 97 72 1436.3 104 1376.7 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