Great Basin Water Supply Outlook, January 1, 2023

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Patrick Kormos
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-July81 94 122 112 140 167
Woodruff Narrows Rsvr, Abv April-July67 83 121 112 150 205
Stewart Dam * April-July82 123 168 104 230 330
Smiths Fork
Border, Nr April-July58 74 94 107 104 125
Logan
Logan, Nr, State Dam, Abv April-July68 88 129 122 140 165
Blacksmith Fork
Hyrum, Nr, Upnl Dam, Abv April-July25 34 44 119 54 81
Little Bear
Paradise April-July24 35 47 121 65 91

*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-July81 93 133 120 145 182
Rockport Res, Wanship, Nr April-July75 96 148 129 166 215
Coalville, Nr April-July74 97 152 128 173 225
Chalk Ck
Coalville April-July18.9 28 45 129 62 75
Weber
Echo Reservoir, Echo, At April-July90 120 190 125 235 295
Lost Ck
Lost Ck Reservoir, Croyden, Nr April-July8.4 11.3 15.5 121 18.7 28
East Canyon Ck
East Canyon Reservoir, Morgan, Nr April-July17 27 33 143 45 58
Weber
Gateway April-July155 225 375 136 445 555
Sf Ogden
Huntsville, Nr April-July42 57 74 142 81 114
Ogden
Pineview Reservoir, Ogden, Nr April-July66 97 138 127 167 225


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-July32 39 42 124 49 56
Big Cottonwood Ck
Salt Lake City, Nr April-July29 36 43 126 48 61
Mill Ck
Salt Lake City, Nr April-July4.4 5.9 7.4 142 8.4 10.2
Dell Fk
Little Dell Reservoir April-July3.4 4.9 6.7 152 8.5 9.5
Lambs Ck
Salt Lake City, Nr April-July4.3 5.5 7.5 174 9 11.1
Parleys Ck
Salt Lake City, Nr April-July9.3 13.4 18.9 164 24 27
Red Butte Ck
Ft Douglas, At, Salt Lake City, Nr April-July0.99 1.5 1.9 122 2.5 3
City Ck
Salt Lake City, Nr April-July5.1 5.9 7.4 114 9.2 10.2
S Willow Ck
Grantsville, Nr April-July1.5 1.8 2.1 70 2.8 3.4


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-July33 42 67 124 87 126
Provo
Woodland, Nr April-July79 98 116 121 142 166
Hailstone, Nr April-July93 114 134 126 164 195
Deer Ck Reservoir April-July106 131 165 139 215 250
American Fork
American Fork, Nr, Up Pwrplnt, Abv April-July20 27 32 128 40 51
West Canyon Ck
Cedar Fort, Nr April-July0.52 1.3 1.6 94 2.3 4.5
Salt Ck
Nephi Powerplant Div, Blo April-July4.4 7.4 11.1 142 14.6 21
Jordan
Utah Lake, Provo, Nr April-July183 240 330 153 465 565

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 Reservoir, Woodruff, Nr 13.3 46 24 11.9 41 28.9 55.8
untitled Bear River
Bear Lake, Nr Lifton 491.0 70 38 655.9 94 698.8 1302.0
untitled Little Bear
Hyrum Reservoir 9.7 97 64 8.6 86 10.0 15.3
untitled Weber
Rockport Res, Wanship, Nr 40.1 116 73 24.4 71 34.5 55.2
Echo Reservoir, Echo, At 45.9 118 62 20.1 52 38.8 73.9
untitled Lost Ck
Lost Ck Reservoir, Croyden, Nr 9.2 78 41 9.4 80 11.8 22.5
untitled East Canyon Ck
East Canyon Reservoir, Morgan, Nr 27.8 86 56 25.3 78 32.2 49.5
untitled Sf Ogden
Causey Reservoir 3.6 102 51 4.0 112 3.6 7.1
untitled Ogden
Pineview Res, Ogden, Nr 39.7 76 36 23.4 45 51.9 110.1
untitled Provo
Jordanelle Reservoir 189.3 86 59 161.9 74 219.3 320.3
Deer Ck Reservoir 74.7 68 50 108.7 100 109.1 149.7
untitled Dell Fk
Little Dell Reservoir 12.7 -99 62 9.9 -99 -9999.0 20.5
untitled Jordan
Utah Lake, Provo, Nr 374.1 52 43 489.4 68 720.9 870.9
untitled
TOTAL 1318.5 67 44 1543.0 79 1959.8 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 1991-2020 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: Patrick Kormos