Lake Powell Water Supply Outlook, March 1, 2015

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-July191 250 102 310
Pine Ck
Fremont Lk, Abv April-July67 92 94 112
New Fork
Big Piney, Nr April-July200 300 85 430
Green
Fontenelle Res, Fontenelle Nr April-July490 710 98 935
Big Sandy
Farson, Nr April-July25 36 69 57
Green
Green River, Wy, Nr April-July470 710 97 940
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July30 44 81 65
Viva Naughton Res April-July38 60 81 90
Blacks Fork
Robertson, Nr April-July45 66 74 97
Ef Smiths Fork
Stateline Res, Robertson,nr April-July13.9 20 77 27
Green
Flaming Gorge Res, Flaming Gorge Dam, At April-July540 825 84 1220


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-July17.5 23 100 31
Steamboat Springs April-July170 230 88 320
Elk
Milner, Nr April-July210 280 88 370
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July23 43 59 65
Yampa
Maybell, Nr April-July525 725 78 970
Little Snake
Slater, Nr April-July73 115 74 157
Dixon, Nr April-July119 205 59 300
Lily, Nr April-July115 210 61 310
Yampa
Deerlodge Park April-July600 925 75 1300
White
Meeker, Nr April-July175 230 82 320
Watson, Nr April-July180 240 86 340


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-July5.9 11.3 54 19.6
Ashley Ck
Vernal, Nr April-July12.9 23 46 43
West Fork Duchesne
Vat Diversion, Blo April-July5.8 9.5 51 13.7
Duchesne
Tabiona, Nr April-July54 72 67 92
Rock Ck
Upper Stillwater Res April-July42 57 77 73
South Fork Rock Ck
Docs Div, Blo April-July2.9 4.6 63 6.3
Rock Ck
Mountain Home, Nr April-July47 68 77 84
Currant Ck
Currant Ck Res April-July4.2 9.3 47 14
Strawberry
Solider Springs,nr April-July15.5 27 38 48
Starvation Res, Duchesne, Nr April-July30 53 47 83
Duchesne
Duchesne, Nr, Knight Div, Abv April-July100 138 71 170
Lake Fork
Moon Lake Res, Mtn Home, Nr April-July30 47 71 59
Yellowstone
Altonah, Nr April-July32 46 75 60
Whiterocks
Whiterocks, Nr April-July21 32 59 48
Uinta
Neola, Nr April-July26 45 61 65
Duchesne
Myton April-July110 182 55 270
Randlett, Nr April-July118 190 49 295


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-July3.2 7.5 48 12.2
Fish Ck
Scofield, Nr, Reservoir, Abv April-July11.9 18 60 27
Price
Scofield Res, Scofield, Nr April-July15.3 24 59 35
Green
Green River, Ut April-July1500 2140 72 3000
Huntington Ck
Electric Lake April-July3.9 6.5 49 11.5
Power Plant, Blo April-July20 26 65 40
Seeley Ck
Joes Vly Res, Orangeville, Nr April-July24 38 68 56
Ferron Ck
Ferron, Nr April-July19 31 82 45
Muddy Ck
Emery, Nr April-July11 15.5 78 24


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-July170 230 105 305
Willow Ck
Willow Ck Res, Granby, Nr April-July29 44 94 70
Fraser
Winter Park April-July16 20 103 25
Williams Fork
Williams Fork Res, Parshall, Nr April-July80 100 104 135
Muddy Ck
Wolford Mountain Reservoir April-July30 50 93 70
Blue
Dillon Res April-July150 188 115 235
Green Mtn Res April-July240 310 113 395
Colorado
Kremmling, Nr April-July700 910 106 1200
Eagle
Gypsum, Blo April-July250 320 96 460
Colorado
Dotsero, Nr April-July1100 1430 102 1920
Frying Pan
Ruedi Res, Basalt, Nr April-July100 130 94 180
Roaring Fork
Glenwood Springs April-July485 600 87 825
Colorado
Glenwood Springs, Blo April-July1600 2000 95 2700
Cameo, Nr April-July1700 2110 89 2960
Plateau Ck
Cameo, Nr April-July35 55 44 95
Colorado
Cisco, Nr April-July2850 3650 82 5300
Lake Powell, Glen Cyn Dam, At April-July3470 5100 71 7200


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-July75 90 91 125
Almont April-July112 138 89 190
East
Almont April-July103 133 73 195
Gunnison
Gunnison, Nr April-July210 290 78 415
Tomichi Ck
Gunnison April-July49 70 95 112
Lake Fork
Gateview April-July90 127 103 180
Gunnison
Blue Mesa Res April-July450 600 89 860
Morrow Point Res April-July500 650 88 910
Crystal Res April-July580 730 87 990
Muddy Ck
Paonia Res, Bardine, Nr March-June40 58 60 90
April-July40 58 60 90
Nf Gunnison
Somerset, Nr April-July150 200 68 300
Surface Ck
Cedaredge April-July6 10 60 15
Uncompahgre
Ridgway Res April-July68 91 90 130
Colona April-July90 118 86 185
Delta April-July65 90 80 162
Gunnison
Grand Junction, Nr April-July930 1180 80 1850


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-July125 200 82 285
Mcphee Res April-July140 230 78 350
San Miguel
Placerville, Nr April-July83 110 86 150
Dolores
Cisco, Nr April-July265 400 71 650


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-July80 125 58 185
Carracas, Nr April-July135 200 53 300
Navajo Res, Archuleta, Nr April-July215 415 56 650
Farmington April-July370 655 60 970
Bluff, Nr April-July340 630 57 930
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July24 35 65 50
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July25 38 58 52
Piedra
Arboles, Nr April-July75 136 65 200
Los Pinos
Vallecito Res, Bayfield, Nr April-July95 150 77 200
Animas
Durango April-July220 315 76 450
Florida
Lemon Res, Durango, Nr April-July21 38 69 55
La Plata
Hesperus April-July9 15 65 24
Mancos
Mancos, Nr April-July10 19 61 31

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 209.8 164 61 136.4 107 127.6 344.8
untitled Big Sandy
Big Sandy Res, Farson, Nr 22.5 149 59 9.7 65 15.1 38.3
Blacks Fork
Meeks Cabin 23.9 194 80 14.4 117 12.3 29.9
untitled Ef Smiths Fork
Stateline Res, Robertson,nr 8.6 161 62 7.1 132 5.4 13.9
untitled Green
Flaming Gorge Res, Flaming Gorge Dam, At 3206.6 106 86 2871.2 95 3015.6 3749.0
untitled Strawberry
Solider Springs,nr 835.6 127 76 832.5 126 660.2 1105.9
Starvation Res, Duchesne, Nr 154.4 107 93 156.3 108 144.5 165.3
untitled Rock Ck
Upper Stillwater Res 14.4 188 46 10.3 135 7.6 31.4
untitled Lake Fork
Moon Lake Res, Mtn Home, Nr 31.9 120 87 24.7 93 26.6 36.5
untitled Big Brush Ck
Red Fleet Res, Vernal, Nr 11.9 64 46 11.3 61 18.5 25.7
untitled Price
Scofield Res, Scofield, Nr 12.4 41 19 15.8 52 30.6 65.8
untitled Seeley Ck
Joes Vly Res, Orangeville, Nr 41.1 102 66 31.2 78 40.2 62.5
untitled Huntington Ck
Electric Lake 18.5 99 59 16.9 90 18.8 31.5
untitled
TOTAL 4591.6 111 81 4137.8 100 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 484.0 146 99 323.9 98 332.0 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 9.5 115 104 9.1 111 8.2 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 78.1 125 81 76.5 123 62.4 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 45.4 103 69 43.6 98 44.2 66.0
untitled Blue
Dillon Res 244.8 112 96 237.2 108 219.3 254.0
Green Mtn Res 70.8 96 48 72.4 98 73.5 146.9
untitled Homestake Ck
Homestake Res -9999.0 -99 -99 0.8 3 30.7 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 78.2 115 77 74.5 110 67.9 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 15.0 113 45 16.5 125 13.2 32.9
untitled Taylor
Taylor Park Res 78.0 119 73 71.6 109 65.7 106.2
untitled Gunnison
Blue Mesa Res 546.6 113 66 398.3 83 482.2 829.5
Morrow Point Res 110.1 99 94 107.7 97 111.1 117.0
Crystal Res 16.7 106 95 14.3 91 15.8 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 1.2 25 7 0.7 15 4.7 16.7
untitled Uncompahgre
Ridgway Res 77.5 112 93 75.5 109 69.4 83.0
untitled Dolores
Mcphee Res 186.0 68 49 187.6 69 272.3 381.1
untitled
TOTAL 2041.8 111 74 1710.4 91 1842.0 2749.1
Colorado
Lake Powell 11023.6 65 45 9563.1 56 17054.6 24322.0
untitled
TOTAL 11023.6 65 45 9563.1 56 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 99.8 157 80 97.8 154 63.5 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 1095.9 85 65 966.0 75 1292.2 1696.0
untitled Florida
Lemon Res, Durango, Nr 22.3 106 56 17.2 82 21.0 39.8
untitled
TOTAL 1218.0 88 65 1081.0 79 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