Upper Colorado Water Supply Outlook, June 1, 2020

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-July190 205 220 100 235 250
June-July97 112 127 88 142 157
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July34 37 40 85 44 48
June-July7 10 13 62 17 21
Fraser
Winter Park April-July16 17.2 18.4 95 20 22
June-July10 11.2 12.4 87 14 16
Williams Fork
Williams Fork Reservoir, Parshall April-July75 80 86 90 93 100
June-July40 45 51 78 58 65
Muddy Ck
Wolford Mountain Reservoir April-July58 62 66 122 71 75
June-July8.1 12.1 16.1 83 21 25
Blue
Dillon Reservoir April-July135 145 155 95 165 175
June-July78 88 98 89 108 118
Green Mtn Reservoir April-July225 240 255 93 275 290
June-July125 140 155 84 175 190
Colorado
Kremmling, Nr April-July720 770 825 96 880 930
June-July335 385 440 84 495 545
Eagle
Gypsum, Blo April-July235 255 275 82 295 315
June-July117 137 157 73 177 197
Colorado
Dotsero, Nr April-July1080 1150 1220 87 1300 1380
June-July510 580 650 77 730 810
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July100 110 120 86 130 140
June-July53 63 73 82 83 93
Roaring Fork
Glenwood Springs April-July440 475 510 74 550 590
June-July255 290 325 71 365 405
Colorado
Glenwood Springs, Blo April-July1500 1640 1780 84 1940 2100
June-July715 855 995 77 1160 1320
Cameo, Nr April-July1600 1720 1850 78 2000 2150
June-July790 910 1040 73 1190 1340
Plateau Ck
Cameo, Nr April-July32 36 40 32 50 60
June-July2.1 6.1 10.1 21 20 30
Colorado
Cisco, Nr April-July2250 2500 2700 61 2900 3150
June-July960 1210 1410 60 1610 1860
Lake Powell, Glen Cyn Dam, At April-July3520 3760 4100 57 4430 4720
June-July1500 1740 2080 55 2410 2700


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-July61 65 69 70 73 79
June-July30 34 38 61 42 48
Almont April-July88 96 103 66 109 118
June-July43 51 58 62 64 73
East
Almont April-July103 110 116 64 125 137
June-July45 52 58 55 67 79
Gunnison
Gunnison, Nr April-July200 215 235 64 250 275
June-July90 106 122 57 140 165
Tomichi Ck
Gunnison April-July36 41 44 59 48 52
June-July12 16.9 20 54 24 28
Lake Fork
Gateview April-July67 74 79 64 86 95
June-July31 38 43 53 50 59
Gunnison
Blue Mesa Reservoir April-July350 375 395 59 425 470
June-July145 174 193 51 220 265
Morrow Point Reservoir April-July370 405 425 57 450 495
June-July155 189 210 52 235 280
Crystal Reservoir April-July405 440 465 56 500 540
June-July170 205 230 51 265 305
Muddy Ck
Paonia Reservoir, Bardine, Nr March-June29 30 31 32 32 35
April-July28 29 30 31 32 35
June-June3.5 4.4 5.5 24 6.5 9.5
June-July4.9 5.9 6.9 24 8.9 11.9
Nf Gunnison
Somerset, Nr April-July134 139 148 50 159 177
June-July32 37 46 40 57 75
Surface Ck
Cedaredge April-July5.4 6 6.4 38 6.6 7.5
June-July1 1.6 2 26 2.2 3.1
Uncompahgre
Ridgway Reservoir April-July48 52 55 54 59 64
June-July27 31 34 52 38 43
Colona April-July47 50 54 39 61 69
June-July24 27 31 38 38 46
Delta April-July25 30 33 29 37 42
June-July7 12.7 15.5 27 18.9 24
Gunnison
Grand Junction, Nr April-July600 640 685 46 750 850
June-July210 250 295 42 360 460


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-July87 92 96 39 102 114
June-July19 24 28 30 34 46
Mcphee Reservoir April-July86 91 95 32 102 115
June-July19 24 28 29 35 48
San Miguel
Placerville, Nr April-July53 58 64 50 70 76
June-July24 29 35 47 41 47
Dolores
Cisco, Nr April-July142 148 155 27 171 205
June-July39 45 52 28 68 100

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 483.3 133 99 375.7 103 363.6 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 8.9 100 98 8.1 91 8.9 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 88.3 121 91 80.3 110 73.0 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 66.0 110 100 57.2 95 59.9 66.0
untitled Blue
Dillon Reservoir 245.6 106 97 186.6 80 232.7 254.0
Green Mtn Reservoir 108.5 121 74 85.4 95 89.8 146.9
untitled Homestake Ck
Homestake Reservoir 29.2 118 68 13.2 53 24.8 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 79.4 102 78 66.1 85 78.0 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 25.9 84 79 24.1 78 30.8 32.9
untitled Taylor
Taylor Park Reservoir 86.0 115 81 58.8 79 74.7 106.2
untitled Gunnison
Blue Mesa Reservoir 549.7 96 66 447.2 78 575.3 829.5
Morrow Point Reservoir 106.5 94 91 112.8 100 113.2 117.0
Crystal Reservoir 17.4 104 99 18.9 113 16.7 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 15.7 100 94 6.8 43 15.7 16.7
untitled Uncompahgre
Ridgway Reservoir 67.9 96 82 59.1 84 70.7 83.0
untitled Dolores
Mcphee Reservoir 283.4 81 74 333.7 96 347.8 381.1
untitled
TOTAL 2261.8 104 81 1934.1 89 2175.6 2792.1
Colorado
Lake Powell 12238.5 67 50 10343.1 57 18186.3 24322.0
untitled
TOTAL 12238.5 67 50 10343.1 57 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, Ashley Nielson