Great Basin Water Supply Outlook, June 1, 2017

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

Contents

Great Basin Summary






*Median of forecasts within each basin.


Bear Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Weber Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Six Creeks Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Utah Lake Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.


Bear 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
Bear
Utah April-July159 164 169 151 174 184
June-July85 90 95 144 100 110
Woodruff Narrows Rsvr, Abv April-July170 180 185 153 192 205
June-July62 72 77 135 84 95
Montpelier, Nr, Stewart Dam, Blo * April-July460 475 505 277 535 570
June-July137 152 182 200 210 245
Smiths Fork
Border, Nr April-July154 162 166 187 169 177
June-July70 78 82 164 85 93
Logan
Logan, Nr, State Dam, Abv April-July180 188 195 176 210 220
June-July85 93 100 164 115 125
Blacksmith Fork
Hyrum, Nr, Upnl Dam, Abv April-July78 83 86 200 91 95
June-July21 26 29 179 34 38
Little Bear
Paradise April-July71 75 79 168 85 93
June-July8 11.6 15.9 137 22 30

*Regulated Forecast, i.e. Observed flow uncorrected for upstream diversion.

Weber 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
Weber
Oakley, Nr April-July152 159 165 140 172 184
June-July78 85 91 142 98 110
Rockport Res, Wanship, Nr April-July165 175 184 139 194 205
June-July78 88 97 152 107 118
Coalville, Nr April-July172 180 188 140 195 210
June-July80 88 96 152 103 117
Chalk Ck
Coalville April-July50 55 60 146 65 70
June-July9 14 18.9 120 24 29
Weber
Echo Res, Echo, At April-July225 235 245 143 260 275
June-July92 102 110 147 126 143
Lost Ck
Lost Ck Res, Croydon, Nr April-July26 27 28 209 29 30
June-July2 3.6 3.8 131 4.7 6
East Canyon Ck
East Canyon Res, Morgan, Nr April-July24 26 28 104 30 34
June-July3 4.8 6.6 79 8.8 12.8
Weber
Gateway April-July410 430 460 142 490 530
June-July111 131 160 145 190 230
Sf Ogden
Huntsville, Nr April-July86 91 94 168 98 106
June-July10 15 17.8 128 22 30
Ogden
Pineview Res, Ogden, Nr April-July160 170 177 157 190 210
June-July11.8 22 29 126 42 60


Six Creeks 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
Little Cottonwood Ck
Salt Lake City, Nr April-July44 46 48 126 50 54
June-July29 31 33 138 35 39
Big Cottonwood Ck
Salt Lake City, Nr April-July34 36 38 106 40 42
June-July18 20 22 115 24 26
Mill Ck
Salt Lake City, Nr April-July5.4 5.9 6.3 98 6.7 7.2
June-July2.6 3.1 3.5 106 3.9 4.4
Dell Fk
Little Dell Res April-July4.6 5.1 5.5 100 5.9 6.5
June-July-0.59 -0.09 0.31 23 0.71 1.3
Parleys Ck
Salt Lake City, Nr April-July11 11.5 12.1 85 13.2 14.5
June-July2.2 2.7 3.3 70 4.4 5.7
Emigration Ck
Salt Lake City, Nr April-July3.7 4 4.4 110 4.8 5.3
June-July-0.01 0.29 0.69 61 1.1 1.6
City Ck
Salt Lake City, Nr April-July7.5 8 8.5 110 8.9 9.4
June-July2.7 3.2 3.7 103 4.1 4.6
S Willow Ck
Grantsville, Nr April-July3.4 3.6 3.9 126 4.1 4.5
June-July1.3 1.5 1.8 107 2 2.4


Utah Lake 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
Spanish Fork
Castilla, Nr April-July60 65 69 100 75 80
June-July8.7 13.7 17.7 74 24 29
Provo
Woodland, Nr April-July145 153 159 159 165 173
June-July66 74 80 170 86 94
Hailstone, Nr April-July159 168 175 159 187 194
June-July68 77 84 162 96 103
Deer Ck Res April-July205 220 230 181 245 260
June-July83 94 106 193 121 136
American Fork
American Fork, Nr, Up Pwrplnt, Abv April-July34 36 38 123 41 44
June-July18.5 21 23 127 26 29
West Canyon Ck
Cedar Fort, Nr April-July1.3 1.5 1.7 97 2 2.4
June-July0.2 0.41 0.61 74 0.85 1.3
Jordan
Utah Lake, Provo, Nr April-July445 465 490 151 515 550
June-July173 193 220 173 245 280

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).

Great Basin 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 Bear
Woodruff Narrows Res, Woodruff, Nr 56.3 120 101 58.2 124 47.1 55.8
untitled Bear River
Bear Lake, Nr Lifton 1199.9 145 92 752.0 91 829.8 1302.0
untitled Little Bear
Hyrum Reservoir 14.6 100 96 14.7 100 14.6 15.3
untitled Weber
Rockport Res, Wanship, Nr 50.8 100 92 48.1 95 50.8 55.2
Echo Res, Echo, At 73.5 110 99 66.8 100 67.0 73.9
untitled Lost Ck
Lost Ck Res, Croydon, Nr 22.9 132 102 20.7 119 17.4 22.5
untitled East Canyon Ck
East Canyon Res, Morgan, Nr 50.1 109 101 37.8 83 45.8 49.5
untitled Sf Ogden
Causey Res 7.2 103 102 7.2 102 7.0 7.1
untitled Ogden
Pineview Res, Ogden, Nr 110.1 112 100 110.7 113 97.9 110.1
untitled Jordanelle Dam
294.5 101 92 235.1 81 290.9 320.3
untitled Provo
Deer Ck Res 142.0 106 95 139.9 105 133.8 149.7
untitled Dell Fk
Little Dell Res 17.0 -99 83 13.2 -99 -9999.0 20.5
untitled Jordan
Utah Lake, Provo, Nr 637.5 76 73 484.4 57 844.2 870.9
untitled
TOTAL 2659.3 109 88 1975.5 81 2446.2 3052.8

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: B.Bernard