Upper Colorado Water Supply Outlook, June 1, 2019

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Cody Moser, Greg Smith
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-July220 230 245 111 260 275
June-July169 179 194 134 210 225
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July62 65 69 147 73 77
June-July30 33 37 176 41 45
Fraser
Winter Park April-July17 18.4 19.7 102 21 23
June-July14 15.4 16.7 118 18 20
Williams Fork
Williams Fork Reservoir, Parshall April-July93 99 105 109 111 118
June-July66 72 78 120 84 91
Muddy Ck
Wolford Mountain Reservoir April-July60 63 66 122 70 74
June-July27 30 33 171 37 41
Blue
Dillon Reservoir April-July210 220 230 141 240 255
June-July171 181 191 174 200 215
Green Mtn Reservoir April-July330 345 360 131 380 400
June-July255 270 285 155 305 325
Colorado
Kremmling, Nr April-July980 1020 1070 124 1130 1190
June-July670 710 760 145 820 880
Eagle
Gypsum, Blo April-July410 430 450 134 475 500
June-July310 330 350 163 375 400
Colorado
Dotsero, Nr April-July1620 1680 1750 125 1840 1920
June-July1130 1190 1260 150 1350 1430
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July160 167 175 126 183 190
June-July125 132 140 157 148 155
Roaring Fork
Glenwood Springs April-July815 850 880 128 920 955
June-July620 655 685 151 725 760
Colorado
Glenwood Springs, Blo April-July2400 2550 2700 128 2860 3000
June-July1680 1830 1980 152 2140 2280
Cameo, Nr April-July2750 2880 3000 127 3150 3300
June-July1950 2080 2200 155 2350 2500
Plateau Ck
Cameo, Nr April-July170 178 185 149 195 205
June-July105 113 120 245 130 140
Colorado
Cisco, Nr April-July5850 6050 6250 141 6500 6700
June-July3690 3890 4090 175 4340 4540
Lake Powell, Glen Cyn Dam, At April-July9450 9910 10300 144 10650 11250
June-July5700 6160 6550 174 6900 7500


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-July128 131 140 141 145 152
June-July97 100 109 176 114 121
Almont April-July200 205 215 139 220 230
June-July147 153 162 172 168 177
East
Almont April-July235 240 250 137 260 270
May-July0 0 0 0 0 0
June-July165 170 180 170 189 200
Gunnison
Gunnison, Nr April-July495 505 520 141 535 550
June-July345 355 370 172 385 400
Tomichi Ck
Gunnison April-July130 135 140 189 148 156
June-July70 75 80 216 88 96
Lake Fork
Gateview April-July177 184 190 154 199 215
June-July140 147 153 189 162 178
Gunnison
Blue Mesa Reservoir April-July1010 1020 1040 154 1070 1120
June-July670 685 705 186 730 780
Morrow Point Reservoir April-July1110 1120 1140 154 1170 1220
June-July730 745 765 189 790 840
Crystal Reservoir April-July1250 1260 1280 153 1310 1360
June-July830 845 865 192 890 940
Muddy Ck
Paonia Reservoir, Bardine, Nr March-June129 132 135 141 138 140
April-July136 139 143 147 145 150
June-June47 50 53 230 56 58
June-July58 61 64 221 67 69
Nf Gunnison
Somerset, Nr April-July375 385 390 132 395 405
June-July205 215 220 193 225 235
Surface Ck
Cedaredge April-July28 29 31 185 33 35
June-July19 20 22 289 24 26
Uncompahgre
Ridgway Reservoir April-July121 125 128 127 133 140
June-July94 98 101 155 106 113
Colona April-July155 161 168 123 175 185
June-July119 125 132 163 139 149
Delta April-July154 161 170 150 177 185
June-July94 101 110 193 117 125
Gunnison
Grand Junction, Nr April-July2120 2160 2190 148 2250 2330
June-July1290 1330 1360 196 1420 1500


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-July320 330 340 139 350 360
June-July176 186 196 213 205 215
Mcphee Reservoir April-July405 415 425 144 435 450
June-July184 194 205 211 215 230
San Miguel
Placerville, Nr April-July153 160 165 129 171 178
June-July100 107 112 149 118 125
Dolores
Cisco, Nr April-July840 855 870 154 890 920
June-July370 385 400 217 420 450

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 375.7 103 77 489.9 135 363.6 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 8.1 91 89 9.4 106 8.9 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 79.9 109 82 88.1 121 73.0 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 57.2 95 87 66.8 111 59.9 66.0
untitled Blue
Dillon Reservoir 186.4 80 73 257.0 110 232.7 254.0
Green Mtn Reservoir 85.4 95 58 95.9 107 89.8 146.9
untitled Homestake Ck
Homestake Reservoir 13.2 53 31 35.4 143 24.8 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 66.1 85 65 81.2 104 78.0 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 24.1 78 73 24.9 81 30.8 32.9
untitled Taylor
Taylor Park Reservoir 58.8 79 55 83.9 112 74.7 106.2
untitled Gunnison
Blue Mesa Reservoir 447.2 78 54 512.6 89 575.3 829.5
Morrow Point Reservoir 112.8 100 96 112.0 99 113.2 117.0
Crystal Reservoir 18.9 113 108 15.9 95 16.7 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 6.8 43 41 15.6 100 15.7 16.7
untitled Uncompahgre
Ridgway Reservoir 59.1 84 71 64.4 91 70.7 83.0
untitled Dolores
Mcphee Reservoir 333.7 96 88 257.2 74 347.8 381.1
untitled
TOTAL 1933.4 89 69 2210.3 102 2175.6 2792.1
Colorado
Lake Powell 10343.1 57 43 12885.9 71 18186.3 24322.0
untitled
TOTAL 10343.1 57 43 12885.9 71 18186.3 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 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:
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, Greg Smith