Lower Colorado Water Supply Outlook, March 1, 2015

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.

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

	Forecast Period	90% Exceedance Volume	50% Exceedance Volume	Percent Median	10% Exceedance Volume
Salt
Roosevelt, Nr	January-May	105	205	66	260
	March-May	35	135	56	192
Tonto Ck
Roosevelt, Nr, Gun Ck, Abv	January-May	19.1	32	76	53
	March-May	6.2	19.1	87	40
Verde
Blo Tangle Ck, Abv Horsehoe Dam	January-May	112	158	101	240
	March-May	71	117	109	198

	Forecast Period	90% Exceedance Volume	50% Exceedance Volume	Percent Median	10% Exceedance Volume
Gila
Gila, Nr	January-May	57	63	113	75
	March-May	16	22	65	34
Virden, Nr, Blue Ck, Blo	January-May	62	70	92	83
	March-May	18	26	60	39
Solomon, Nr, Head Of Safford Vly	January-May	126	142	104	170
	March-May	34	50	56	78
San Carlos Res, Coolidge Dam, At	January-May	81	98	103	125
	March-May	8.9	26	49	53
San Francisco
Glenwood, Nr	January-May	15.1	18.1	86	25
	March-May	5.1	8.1	53	14.5
Clifton	January-May	60	72	118	81
	March-May	11.2	23	61	32

	Forecast Period	90% Exceedance Volume	50% Exceedance Volume	Percent Median	10% Exceedance Volume
Little Colorado
Lyman Lk, Abv, St. Johns, Nr	January-June	1.1	1.7	24	5.2
	March-June	0.6	1.2	21	4.7
Zuni
Black Rock Res, Abv	January-May	0.16	0.25	53	0.86
	March-May	0.05	0.14	61	0.75
Chevelon Ck
Winslow, Nr, Wildcat Cyn, Blo	January-May	4.8	7.4	53	12.8
	March-May	0.2	2.8	20	8.2

	EOM Contents	Percent EOM Average	Percent Usable Capacity	Last Year EOM	Last Year %Average	EOM Average	Usable Capacity
Salt
Roosevelt	757.7	79	46	796.9	84	953.2	1653.0
Horse Mesa	228.1	99	93	232.9	101	231.1	245.1
Mormon Flat	54.8	101	95	54.4	100	54.3	57.9
Stewart Mountain	62.7	100	90	63.9	101	63.0	69.8
Horseshoe	39.2	82	36	41.4	87	47.8	109.2
Bartlett	87.0	72	49	95.6	79	120.3	178.2
untitled
TOTAL	1229.5	84	53	1285.1	87	1469.7	2313.2


Bill Williams
Alamo	53.3	34	5	59.2	37	158.3	1045.0
Agua Fria
Lake Pleasant	784.9	107	90	669.7	91	734.3	869.9
Gila
San Carlos	134.2	33	15	117.3	29	404.1	875.0
Colorado
Lake Powell	11023.6	65	45	9563.1	56	17054.6	24322.0
Lake Mead	10769.0	52	41	12437.0	60	20575.4	26120.0
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TOTAL	22765.0	58	43	22846.4	59	38926.8	53231.9

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

Lower Colorado Water Supply Outlook, March 1, 2015

Lower Colorado Summary

Salt Basin Conditions

Gila Basin Conditions

Little Colorado Basin Conditions

Salt Specific Site Forecasts (kaf)

Gila Specific Site Forecasts (kaf)

Little Colorado Specific Site Forecasts (kaf)

Lower Colorado End of Month Reservoir Contents (kaf)

Precipitation Maps

Definitions

Additional Information