Great Basin Water Supply Outlook, June 1, 2016

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.

Prepared by W.P.Miller, B.Bernard
NOAA, National Weather Service
Colorado Basin River Forecast Center
Salt Lake City, Utah
www.cbrfc.noaa.gov

Contents

Water Supply Forecast Discussion
Bear Basin Conditions
Weber Basin Conditions
Six Creeks Basin Conditions
Utah Lake Basin Conditions
Bear Specific Site Forecasts
Weber Specific Site Forecasts
Six Creeks Specific Site Forecasts
Utah Lake Specific Site Forecasts
Reservoir Contents
Precipitation Maps
Definitions
Additional Information
Questions or Comments

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-July	95	101	105	94	109	114
	June-July	53	59	63	95	67	72
Woodruff Narrows Rsvr, Abv	April-July	94	101	106	88	110	117
	June-July	35	42	47	82	51	58
Montpelier, Nr, Stewart Dam, Blo *	April-July	108	111	115	63	121	135
	June-July	40	43	47	52	53	67
Smiths Fork
Border, Nr	April-July	80	84	87	98	90	94
	June-July	35	39	42	84	45	49
Logan
Logan, Nr, State Dam, Abv	April-July	91	94	97	87	100	105
	June-July	40	43	46	75	49	54
Blacksmith Fork
Hyrum, Nr, Upnl Dam, Abv	April-July	31	-977.77	34	79	34	37
	June-July	9.3	-999	12.3	76	13.2	15.3
Little Bear
Paradise	April-July	28	-974.06	30	64	31	33
	June-July	2.9	-999	4.9	42	6	7.9

*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-July	92	95	102	86	106	110
	June-July	47	50	57	89	61	65
Rockport Res, Wanship, Nr	April-July	83	89	95	72	99	105
	June-July	40	46	52	81	56	62
Coalville, Nr	April-July	89	94	95	71	99	110
	June-July	41	46	47	75	51	62
Chalk Ck
Coalville	April-July	25	25	29	71	30	31
	June-July	6	6.7	10	64	11.1	12.8
Weber
Echo Res, Echo, At	April-July	104	112	119	70	124	136
	June-July	40	48	55	73	60	72
Lost Ck
Lost Ck Res, Croydon, Nr	April-July	10.5	10.8	11.2	84	11.2	11.8
	June-July	1.2	1.6	1.9	67	1.9	2.5
East Canyon Ck
East Canyon Res, Morgan, Nr	April-July	12.7	13.2	14	52	14.2	15.1
	June-July	2.6	3.1	3.9	46	4.1	5
Weber
Gateway	April-July	192	200	210	65	215	260
	June-July	50	60	68	62	74	120
Sf Ogden
Huntsville, Nr	April-July	48	51	53	95	53	58
	June-July	5	7.5	9.9	71	10.1	15
Ogden
Pineview Res, Ogden, Nr	April-July	80	82	88	78	89	95
	June-July	5	7.3	13	57	14.4	20

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-July	28	28	29	76	29	30
	June-July	17.4	17.7	18.2	76	18.7	19.6
Big Cottonwood Ck
Salt Lake City, Nr	April-July	23	23	23	64	24	25
	June-July	10.1	10.3	10.6	55	11.2	11.9
Mill Ck
Salt Lake City, Nr	April-July	2.7	2.8	3	47	3.1	3.3
	June-July	1.5	1.6	1.8	55	1.9	2.1
Dell Fk
Little Dell Res	April-July	2	2.3	2.5	45	2.8	3
	June-July	0.25	0.5	0.75	56	1	1.3
Parleys Ck
Salt Lake City, Nr	April-July	5.1	5.1	6	42	6	6.9
	June-July	1	1	1.9	40	1.9	2.8
Emigration Ck
Salt Lake City, Nr	April-July	1	1.1	1.2	29	1.3	1.5
	June-July	0.25	0.3	0.38	33	0.5	0.7
City Ck
Salt Lake City, Nr	April-July	3.7	4	4.4	57	4.6	4.9
	June-July	1.2	1.5	2	54	2.1	2.4
S Willow Ck
Grantsville, Nr	April-July	2.1	2.2	2.4	77	2.4	2.7
	June-July	0.7	0.82	0.96	57	1	1.3

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-July	13.4	13.4	13.4	19.4	13.5	14.3
	June-July	8.3	8.3	8.3	35	8.4	9.2
Provo
Woodland, Nr	April-July	84	85	86	86	87	92
	June-July	39	40	41	87	42	47
Hailstone, Nr	April-July	96	99	100	91	101	104
	June-July	43	46	47	90	48	51
Deer Ck Res	April-July	97	99	100	79	102	107
	June-July	38	40	41	75	43	48
American Fork
American Fork, Nr, Up Pwrplnt, Abv	April-July	16.6	16.9	17.2	55	17.8	18.4
	June-July	9.6	9.9	10.2	56	10.8	11.4
West Canyon Ck
Cedar Fort, Nr	April-July	0.32	0.36	0.4	23	0.42	0.52
	June-July	0.1	0.14	0.18	22	0.2	0.3
Jordan
Utah Lake, Provo, Nr	April-July	193	185	198	61	190	215
	June-July	75	67	80	63	72	96

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	56.4	125	101	54.6	121	45.0	55.8
untitled Bear River
Bear Lake, Nr Lifton	674.3	87	52	716.7	93	770.8	1302.0
untitled Little Bear
Hyrum Reservoir	13.1	92	86	14.7	104	14.2	15.3
untitled Weber
Rockport Res, Wanship, Nr	45.1	113	82	44.9	112	40.1	55.2
Echo Res, Echo, At	49.1	91	66	46.3	85	54.3	73.9
untitled Lost Ck
Lost Ck Res, Croydon, Nr	16.3	122	72	15.0	113	13.3	22.5
untitled East Canyon Ck
East Canyon Res, Morgan, Nr	32.6	82	66	31.6	80	39.5	49.5
untitled Sf Ogden
Causey Res	7.1	142	101	7.1	142	5.0	7.1
untitled Ogden
Pineview Res, Ogden, Nr	103.3	130	94	77.2	97	79.7	110.1
untitled Jordanelle Dam
	180.1	72	56	212.4	85	251.3	320.3
untitled Provo
Deer Ck Res	144.4	117	96	145.3	118	123.5	149.7
untitled Dell Fk
Little Dell Res	12.0	-99	58	12.9	-99	-9999.0	20.5
untitled Jordan
Utah Lake, Provo, Nr	486.1	59	56	554.7	67	827.8	870.9
untitled
TOTAL	1807.9	80	60	1920.4	85	2264.6	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:

Range		Round to
0-1.99		0.01
2.0-19.9		0.1
20-199		1.0
200-999		5.0
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: W.P.Miller, B.Bernard