Upper Colorado Water Supply Outlook, June 1, 2023

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

Contents

Upper Colorado Summary




*Median of forecasts within each basin.


Upper Colorado Mainstem Basin Conditions




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

Gunnison Basin Conditions




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

Dolores Basin Conditions




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


Upper Colorado Mainstem 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
Colorado
Lake Granby, Granby, Nr April-July215 230 240 107 255 275
June-July100 115 125 86 140 160
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July74 78 82 164 88 95
June-July9.8 13.8 17.8 85 24 31
Fraser
Winter Park April-July17.5 19 20 108 21 23
June-July10.9 12.4 13.4 100 14.4 16.4
Williams Fork
Williams Fork Reservoir, Parshall April-July80 85 90 94 96 105
June-July38 43 48 76 54 63
Muddy Ck
Wolford Mountain Reservoir April-July46 49 52 100 56 60
June-July6.9 9.9 12.9 71 16.9 21
Blue
Dillon Reservoir April-July115 125 135 81 145 155
June-July64 74 84 74 94 104
Green Mtn Reservoir April-July210 225 240 86 255 270
June-July114 129 144 77 159 174
Colorado
Kremmling, Nr April-July840 890 940 108 990 1050
June-July360 410 460 88 510 570
Eagle
Gypsum, Blo April-July265 280 300 90 320 345
June-July125 140 160 74 180 205
Colorado
Dotsero, Nr April-July1330 1400 1480 106 1550 1630
June-July580 650 730 87 800 880
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July115 122 130 96 137 145
June-July58 65 73 84 80 88
Roaring Fork
Glenwood Springs April-July760 795 830 127 865 900
June-July445 480 515 118 550 585
Colorado
Glenwood Springs, Blo April-July2130 2250 2380 114 2530 2680
June-July1010 1130 1260 98 1410 1560
Cameo, Nr April-July2550 2680 2800 123 2950 3100
June-July1140 1270 1390 101 1540 1690
Cisco, Nr April-July6000 6200 6400 157 6600 6800
June-July2370 2570 2770 125 2970 3170
Lake Powell, Glen Cyn Dam, At April-July9820 10230 10700 167 11080 11620
June-July3900 4310 4780 140 5160 5700


Gunnison 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
Taylor
Taylor Park Reservoir April-July109 114 118 126 124 134
June-July63 68 72 122 78 88
Almont April-July169 177 184 125 193 205
June-July94 102 109 121 118 130
East
Almont April-July245 255 265 150 275 285
June-July130 139 150 146 158 170
Gunnison
Gunnison, Nr April-July475 490 505 144 525 550
June-July260 275 290 141 310 335
Tomichi Ck
Gunnison April-July80 84 87 130 94 103
June-July28 32 35 103 42 51
Lake Fork
Gateview April-July116 122 127 108 135 146
June-July69 75 80 104 88 99
Gunnison
Blue Mesa Reservoir April-July795 825 845 133 890 940
June-July390 420 440 124 485 535
Morrow Point Reservoir April-July860 890 910 132 965 1020
June-July410 440 460 121 515 570
Crystal Reservoir April-July950 990 1020 132 1070 1140
June-July445 485 515 123 565 635
Muddy Ck
Paonia Reservoir, Bardine, Nr April-July176 182 186 230 191 200
June-July41 47 51 204 56 65
Nf Gunnison
Somerset, Nr April-July460 475 485 183 500 520
June-July155 169 180 171 195 215
Surface Ck
Cedaredge April-July34 35 36 247 37 39
June-July11.4 12.3 13 197 14.4 16.6
Uncompahgre
Ridgway Reservoir April-July103 107 112 122 118 127
June-July62 66 71 120 77 86
Colona April-July129 138 147 123 154 167
June-July68 77 86 119 93 106
Delta April-July144 154 167 176 182 200
June-July55 65 78 150 93 111
Gunnison
Grand Junction, Nr April-July2100 2180 2250 169 2320 2430
June-July800 885 950 148 1020 1130


Dolores 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
Dolores
Dolores April-July370 385 395 184 410 430
June-July102 114 126 154 142 162
Mcphee Reservoir April-July505 515 530 208 545 565
June-July110 120 134 156 150 170
San Miguel
Placerville, Nr April-July148 154 160 139 168 177
June-July88 94 100 147 108 117
Dolores
Cisco, Nr April-July1080 1090 1120 222 1140 1180
June-July270 285 310 170 335 375

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).

Upper Colorado 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 Colorado
Lake Granby, Granby, Nr 476.8 125 97 424.5 111 382.8 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 9.2 105 101 7.1 81 8.8 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 79.3 99 82 88.2 110 79.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 61.1 104 93 49.0 83 59.0 66.0
untitled Blue
Dillon Reservoir 231.1 101 91 215.6 94 228.9 254.0
Green Mtn Reservoir 115.5 121 79 79.3 83 95.3 146.9
untitled Homestake Ck
Homestake Reservoir 17.4 74 41 15.3 65 23.5 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 84.4 109 83 74.7 96 77.5 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 34.6 112 105 26.2 85 30.8 32.9
untitled Taylor
Taylor Park Reservoir 80.5 103 76 74.0 95 78.2 106.2
untitled Gunnison
Blue Mesa Reservoir 589.0 101 71 334.9 58 580.7 827.9
Morrow Point Reservoir 112.0 100 96 110.7 99 111.6 117.0
Crystal Reservoir 16.4 98 94 16.5 98 16.8 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 16.0 116 96 15.6 113 13.8 16.7
untitled Uncompahgre
Ridgway Reservoir 59.1 86 71 65.8 96 68.6 83.0
untitled Dolores
Mcphee Reservoir 366.2 110 96 257.3 77 333.2 381.1
untitled
TOTAL 2348.6 107 84 1854.7 85 2189.2 2790.6
Colorado
Lake Powell 7887.8 52 32 6346.0 42 15119.4 24322.0
untitled
TOTAL 7887.8 52 32 6346.0 42 15119.4 24322.0

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: Cody Moser, Ashley Nielson