Green Water Supply Outlook, May 1, 2020

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Brenda Alcorn
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-July200 220 235 96 260 275
May-July188 210 225 100 250 265
Pine Ck
Fremont Lk, Abv April-July62 71 80 82 87 100
May-July61 70 79 82 86 99
New Fork
Big Piney, Nr April-July175 220 250 70 280 345
May-July153 198 230 70 260 325
Green
Fontenelle Reservoir, Fontenelle, Nr April-July530 610 670 92 755 830
May-July445 525 585 91 670 745
Big Sandy
Farson, Nr April-July23 27 32 62 38 49
May-July20 24 29 60 35 46
Green
Green River, Wy, Nr April-July520 605 670 92 755 830
May-July440 525 590 92 675 750
Hams Fork
Frontier, Nr, Pole Ck, Blo April-July30 36 45 83 53 62
May-July25 31 40 83 48 57
Viva Naughton Reservoir April-July45 52 60 81 71 84
May-July37 44 52 84 63 76
Blacks Fork
Robertson, Nr April-July62 69 75 84 83 93
May-July58 65 71 84 79 89
Ef Smiths Fork
Stateline Reservoir, Robertson,nr April-July21 23 26 100 28 32
May-July20 22 25 96 27 31
Green
Flaming Gorge Reservoir April-July670 765 880 90 1030 1100
May-July555 650 765 91 915 985


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-July17 19 21 91 25 28
May-July10.2 12.2 14 88 18 21
Steamboat Springs April-July225 240 260 100 280 320
May-July187 200 220 100 240 280
Elk
Milner, Nr April-July290 320 340 106 365 405
May-July250 280 300 103 325 365
Elkhead Ck
Long Gulch, Abv, Hayden, Nr April-July62 70 78 107 87 95
May-July40 48 56 112 65 73
Yampa
Maybell, Nr April-July800 860 935 100 1000 1100
May-July655 715 790 102 855 950
Little Snake
Slater, Nr April-July120 133 147 94 158 176
May-July104 117 131 95 142 160
Dixon, Nr April-July230 255 295 86 320 370
May-July189 215 255 86 280 330
Lily, Nr April-July230 255 300 87 335 385
May-July192 215 260 90 295 345
Yampa
Deerlodge Park April-July1010 1100 1220 98 1310 1470
May-July835 925 1040 102 1130 1290
White
Meeker, Nr April-July190 205 220 79 240 270
May-July163 178 195 80 215 245
Watson, Nr April-July180 205 225 80 255 285
May-July154 179 200 85 230 260


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-July14 15.5 17 81 19 23
May-July12.9 14.4 15.9 86 17.9 22
Ashley Ck
Vernal, Nr April-July27 32 40 80 45 55
May-July25 30 38 81 43 53
West Fork Duchesne
Vat Diversion, Blo April-July9.5 10.5 12 65 13.5 15
May-July8.5 9.5 11 64 12.5 14
Duchesne
Tabiona, Nr April-July70 76 87 81 95 105
May-July62 68 79 81 87 97
Rock Ck
Upper Stillwater Reservoir April-July51 57 64 86 70 80
May-July48 54 61 86 67 77
South Fork Rock Ck
Docs Div, Blo April-July4 4.5 5.5 75 6.2 7
May-July3.6 4.1 5.1 74 5.8 6.6
Rock Ck
Mountain Home, Nr April-July60 67 75 85 82 92
May-July56 63 71 85 78 88
Currant Ck
Currant Ck Reservoir April-July11.5 12.5 15 75 16.5 19
May-July8.9 9.9 12.4 73 13.9 16.4
Strawberry
Strawberry Reservoir, Soldier Springs April-July20 23 30 42 37 42
May-July15 17.6 25 43 32 37
Starvation Reservoir, Duchesne, Nr April-July50 55 65 58 75 84
May-July40 45 55 60 65 74
Duchesne
Duchesne, Nr, Knight Div, Abv April-July130 145 160 82 180 195
May-July118 133 148 83 168 183
Lake Fork
Moon Lake Reservoir, Mtn Home, Nr April-July40 44 50 76 55 66
May-July37 41 47 75 52 63
Yellowstone
Altonah, Nr April-July42 49 55 90 60 71
May-July38 45 51 89 56 67
Whiterocks
Whiterocks, Nr April-July29 33 40 74 45 57
May-July27 31 38 75 43 55
Uinta
Neola, Nr April-July43 50 60 81 66 82
May-July40 47 57 80 63 79
Duchesne
Myton April-July150 175 210 64 250 290
May-July129 154 189 64 230 270
Randlett, Nr April-July165 190 220 57 260 310
May-July141 166 196 57 235 285


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-July5.6 6.7 7.5 48 8.6 9.8
May-July4.1 5.2 6 50 7.1 8.3
Fish Ck
Scofield, Nr, Reservoir, Abv April-July19.3 22 24 80 27 31
May-July17.3 19.5 22 85 25 29
Price
Scofield Reservoir, Scofield, Nr April-July26 29 32 78 36 41
May-July22 25 28 80 32 37
Green
Green River, Ut April-July2070 2350 2540 86 2780 3220
May-July1750 2030 2220 87 2460 2900
Huntington Ck
Electric Lake April-July6.1 7.9 9.3 70 10.7 12.3
May-July5.1 6.9 8.3 70 9.7 11.3
Power Plant, Blo April-July25 29 33 83 38 44
May-July22 26 30 81 35 41
Seeley Ck
Joes Vly Reservoir, Orangeville, Nr April-July32 37 42 75 47 53
May-July30 35 40 77 45 51
Ferron Ck
Ferron, Nr April-July24 28 33 87 37 41
May-July22 26 31 89 35 39
Muddy Ck
Emery, Nr April-July9.5 11.3 12.9 65 15.1 17.5
May-July8.3 10.1 11.7 65 13.9 16.3

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 135.8 112 39 95.1 78 121.7 344.8
untitled Big Sandy
Big Sandy Reservoir, Nr Farson 24.5 125 64 17.6 90 19.6 38.3
Blacks Fork
Meeks Cabin 12.1 90 40 6.8 51 13.4 29.9
untitled Ef Smiths Fork
Stateline Reservoir, Robertson,nr 5.8 106 42 4.2 76 5.5 13.9
untitled Green
Flaming Gorge Reservoir 3220.1 107 86 3185.0 105 3021.3 3749.0
untitled Strawberry
Strawberry Reservoir, Soldier Springs 978.8 147 89 860.5 130 663.7 1105.9
Starvation Reservoir, Duchesne, Nr 164.7 110 100 142.6 95 149.7 165.3
untitled Rock Ck
Upper Stillwater Reservoir 6.6 149 21 2.1 48 4.5 31.4
untitled Lake Fork
Moon Lake Reservoir, Mtn Home, Nr 29.7 109 81 15.5 57 27.3 36.5
untitled Big Brush Ck
Red Fleet Reservoir, Vernal, Nr 22.0 115 85 13.3 70 19.0 25.7
untitled Price
Scofield Reservoir, Scofield, Nr 52.2 169 79 28.6 93 30.9 65.8
untitled Seeley Ck
Joes Vly Reservoir, Orangeville, Nr 48.5 121 78 30.0 75 40.0 62.5
untitled Huntington Ck
Electric Lake 22.7 124 72 16.2 89 18.3 31.5
untitled
TOTAL 4723.6 114 83 4417.5 107 4134.9 5700.4

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: Brenda Alcorn