Lower Colorado Water Supply Outlook, February 1, 2023

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.

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	70% Exceedance Volume	50% Exceedance Volume	Percent Median	30% Exceedance Volume	10% Exceedance Volume
Salt
Roosevelt, Nr	January-May	335	400	455	182	575	745
	February-May	190	255	310	138	430	600
Tonto Ck
Roosevelt, Nr, Gun Ck, Abv	January-May	75	87	98	251	138	176
	February-May	12	24	35	113	75	113
Verde
Tangle Ck, Blo, Horseshoe Dam, Abv	January-May	215	255	300	194	400	560
	February-May	105	147	190	165	290	450

	Forecast Period	90% Exceedance Volume	70% Exceedance Volume	50% Exceedance Volume	Percent Median	30% Exceedance Volume	10% Exceedance Volume
Gila
Gila, Nr	January-May	53	61	69	133	94	120
	February-May	28	36	44	100	69	95
Virden, Nr, Blue Ck, Blo	January-May	64	75	88	138	115	149
	February-May	30	41	54	100	81	115
Solomon, Nr, Head Of Safford Vly	January-May	165	195	230	217	310	400
	February-May	65	95	130	140	210	300
San Carlos Reservoir, Coolidge Dam, At	January-May	172	198	230	315	340	450
	February-May	42	68	100	172	210	320
San Francisco
Glenwood, Nr	January-May	28	32	38	205	58	82
	February-May	14	18	24	159	44	68
Clifton	January-May	74	84	97	220	142	192
	February-May	32	42	55	138	100	150

	Forecast Period	90% Exceedance Volume	70% Exceedance Volume	50% Exceedance Volume	Percent Median	30% Exceedance Volume	10% Exceedance Volume
Little Colorado
Lyman Lk, Abv, St. Johns, Nr	January-June	3.1	4	4.9	83	8.4	12.9
	February-June	2.2	3.1	4	73	7.5	12
Zuni
Black Rock Res, Abv	January-May	0.12	0.23	0.33	254	1	2
	February-May	0.09	0.2	0.3	300	1	2
Chevelon Ck
Winslow, Nr, Wildcat Cyn, Blo	January-May	18.8	27	35	252	45	55
	February-May	9	17	25	181	35	45

	EOM Contents	Percent EOM Average	Percent Usable Capacity	Last Year EOM	Last Year %Average	EOM Average	Usable Capacity
Salt
Roosevelt	1241.6	138	75	1164.7	129	901.4	1653.0
Horse Mesa	234.4	106	96	235.7	106	222.0	245.1
Mormon Flat	55.4	102	96	54.6	100	54.5	57.9
Stewart Mountain	64.4	103	92	64.1	103	62.2	69.8
Horseshoe	58.0	154	53	21.3	57	37.6	109.2
Bartlett	136.3	117	76	99.1	85	116.8	178.2
untitled
TOTAL	1790.1	128	77	1639.6	118	1394.6	2313.2


Bill Williams
Alamo	120.2	84	12	137.1	96	143.3	1045.0
Agua Fria
Lake Pleasant	737.4	115	85	757.5	118	641.6	869.9
Gila
San Carlos	22.9	6	3	81.5	22	366.8	875.0
Colorado
Lake Powell	9638.5	56	40	12280.7	71	17338.2	24322.0
Lake Mead	10507.6	51	40	11256.2	55	20452.4	26120.0
untitled
TOTAL	20906.4	54	40	24375.9	63	38798.9	52186.9

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, February 1, 2023

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