Green Water Supply Outlook, June 1, 2021

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Ashley Nielson,Patrick Kormos
NOAA, National Weather Service
Colorado Basin River Forecast Center
Salt Lake City, Utah
www.cbrfc.noaa.gov

Contents

Green Summary




*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 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-July142 158 169 69 184 210
June-July90 106 117 70 132 158
Pine Ck
Fremont Lk, Abv April-July47 56 63 64 69 79
June-July31 40 47 62 53 63
New Fork
Big Piney, Nr April-July110 132 154 43 184 225
June-July56 78 100 39 130 170
Green
Fontenelle Reservoir, Fontenelle, Nr April-July265 305 345 48 400 480
June-July135 175 215 45 270 350
Big Sandy
Farson, Nr April-July18.1 21 24 46 27 35
June-July10 13 16 47 19.3 27
Green
Green River, Wy, Nr April-July255 295 335 46 395 475
June-July130 173 210 44 270 350
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July22 24 26 48 29 34
June-July6 7.9 10.5 40 12.8 18
Viva Naughton Reservoir April-July30 32 35 47 38 44
June-July6 8.2 11.2 36 13.8 20
Blacks Fork
Robertson, Nr April-July40 44 48 54 53 62
June-July14 17.5 22 37 27 36
Ef Smiths Fork
Stateline Reservoir, Robertson,nr April-July13.1 14.6 16.2 62 17.5 20
June-July5 6.5 8.1 46 9.4 12
Green
Flaming Gorge Reservoir April-July305 350 395 40 460 555
June-July135 180 225 38 290 385


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-July6.5 7.7 8.5 37 9.3 11.3
June-July1 2.2 3 35 3.8 5.8
Steamboat Springs April-July90 100 110 42 123 142
June-July20 30 40 34 53 72
Elk
Milner, Nr April-July137 150 162 51 177 200
June-July45 58 70 44 85 110
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July16.7 16.9 17.2 24 17.3 20
June-July0.5 0.75 1 10 1.1 4
Yampa
Maybell, Nr April-July270 295 325 35 360 415
June-July72 97 130 33 165 220
Little Snake
Slater, Nr April-July61 66 71 46 77 85
June-July14 18.5 24 36 30 38
Dixon, Nr April-July80 90 95 28 111 130
June-July15 25 30 22 46 65
Lily, Nr April-July83 94 99 29 114 133
June-July15 26 31 23 46 65
Yampa
Deerlodge Park April-July330 375 415 33 465 550
June-July80 127 165 33 215 300
White
Meeker, Nr April-July88 95 103 37 115 128
June-July30 37 45 31 57 70
Watson, Nr April-July82 91 100 36 112 125
June-July30 39 48 35 60 73


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-July5.8 7 7.5 36 8.5 10
June-July1.4 2.6 3.1 34 4.1 5.6
Ashley Ck
Vernal, Nr April-July14.6 18.5 19.6 39 21 23
June-July4.2 8.1 9.2 38 10.6 12.5
West Fork Duchesne
Vat Diversion, Blo April-July3.9 5 5.5 30 5.7 6.2
June-July0.74 1.8 2.3 25 2.5 3
Duchesne
Tabiona, Nr April-July37 42 45 42 47 49
June-July12.2 17.2 20 33 22 24
Rock Ck
Upper Stillwater Reservoir April-July32 35 38 51 43 44
June-July8.6 11.6 14.6 31 19.5 21
South Fork Rock Ck
Docs Div, Blo April-July1.8 2.3 2.4 33 2.6 3.2
June-July0.73 1.2 1.3 27 1.6 2.1
Rock Ck
Mountain Home, Nr April-July38 44 46 52 48 55
June-July12.4 18.4 20 36 22 29
Currant Ck
Currant Ck Reservoir April-July3 3.5 4.1 21 5 5.7
June-July0.32 0.82 1.4 19 2.3 3
Strawberry
Strawberry Reservoir, Soldier Springs April-July8 9.4 10.1 14 12 16
June-July1.4 2.8 3.5 15 5.4 9.4
Starvation Reservoir, Duchesne, Nr April-July9.5 12.5 14.2 13 17.4 27
June-July0.55 3.5 5.2 14 8.4 18
Duchesne
Duchesne, Nr, Knight Div, Abv April-July75 85 89 46 95 104
June-July25 35 39 34 45 54
Lake Fork
Moon Lake Reservoir, Mtn Home, Nr April-July20 25 27 41 29 34
June-July7.1 12.1 14.1 33 16.1 21
Yellowstone
Altonah, Nr April-July20 25 26 43 29 33
June-July8.2 13.2 14.2 35 17.4 21
Whiterocks
Whiterocks, Nr April-July15 20 21 39 22 26
June-July6.2 11.5 12.1 36 13.3 17.2
Uinta
Neola, Nr April-July19 23 27 36 28 32
June-July8.9 12.9 16.8 34 17.8 22
Duchesne
Myton April-July62 74 76 23 80 93
June-July6.8 19 21 12 25 38
Randlett, Nr April-July66 78 81 21 85 98
June-July11.6 24 27 13 31 44


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-July0.81 0.9 1 6 1.1 2
June-July0.29 0.38 0.48 14 0.58 1.5
Fish Ck
Scofield, Nr, Reservoir, Abv April-July3.5 4 4.3 14 4.7 5.4
June-July0.57 1.1 1.4 14 1.8 2.5
Price
Scofield Reservoir, Scofield, Nr April-July5 5.3 5.5 13 6 7
June-July0.64 0.94 1.1 9 1.6 2.6
Green
Green River, Ut April-July790 870 955 32 1070 1270
June-July320 400 485 31 600 800
Huntington Ck
Electric Lake April-July1.8 2.3 2.4 18 2.5 2.7
June-July0.35 0.85 0.95 20 1.1 1.3
Power Plant, Blo April-July10 12 13.6 34 14.5 16.9
June-July6.3 8.3 9.9 50 10.8 13.2
Seeley Ck
Joes Vly Reservoir, Orangeville, Nr April-July8 10.6 11 20 11.5 13.4
June-July5 7.6 8 25 8.5 10.4
Ferron Ck
Ferron, Nr April-July7.9 9.7 9.9 26 10.5 12.3
June-July1.8 3.6 3.8 18 4.4 6.2
Muddy Ck
Emery, Nr April-July3.3 3.6 3.8 19 4 5.1
June-July1.2 1.6 1.7 14 1.9 3

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 151.6 92 45 203.5 124 164.0 334.0
untitled Big Sandy
Big Sandy Reservoir, Nr Farson 18.8 64 49 31.4 107 29.4 38.3
Blacks Fork
Meeks Cabin 16.6 67 56 28.1 113 24.9 29.9
untitled Ef Smiths Fork
Stateline Reservoir, Robertson,nr 8.3 73 60 14.3 127 11.3 13.9
untitled Green
Flaming Gorge Reservoir 3148.8 103 84 3227.6 105 3071.5 3749.0
untitled Strawberry
Strawberry Reservoir, Soldier Springs 903.4 126 82 1003.1 140 716.0 1105.9
Starvation Reservoir, Duchesne, Nr 152.8 99 92 164.6 106 154.8 165.3
untitled Rock Ck
Upper Stillwater Reservoir 21.5 137 69 18.2 116 15.7 31.4
untitled Lake Fork
Moon Lake Reservoir, Mtn Home, Nr 13.8 48 38 38.2 134 28.6 36.5
untitled Big Brush Ck
Red Fleet Reservoir, Vernal, Nr 17.2 73 67 23.4 100 23.4 25.7
untitled Price
Scofield Reservoir, Scofield, Nr 33.3 69 51 58.9 121 48.5 65.8
untitled Seeley Ck
Joes Vly Reservoir, Orangeville, Nr 37.6 73 60 55.8 108 51.6 62.5
untitled Huntington Ck
Electric Lake 18.0 76 57 26.9 113 23.8 31.5
untitled
TOTAL 4541.6 104 80 4894.2 112 4363.6 5689.6

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


Hydrologist: Ashley Nielson,Patrick Kormos