Upper Colorado Water Supply Outlook, June 1, 2017

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Brenda Alcorn, 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-July215 230 240 109 255 275
June-July130 143 154 106 170 190
Willow Ck
Willow Ck Res, Granby, Nr April-July59 62 65 138 72 75
June-July14 17 20 95 27 30
Fraser
Winter Park April-July18 19.5 21 108 23 25
June-July13.5 15 16.5 116 18.5 20
Williams Fork
Williams Fork Res, Parshall, Nr April-July90 95 105 109 110 117
June-July63 68 78 120 83 90
Muddy Ck
Wolford Mountain Reservoir April-July36 38 42 78 46 49
June-July7 9.1 13.1 68 17.1 20
Blue
Dillon Res April-July160 175 185 113 195 205
June-July109 124 134 122 144 154
Green Mtn Res April-July260 285 305 111 320 340
June-July170 194 215 117 230 250
Colorado
Kremmling, Nr April-July850 900 950 110 1030 1070
June-July480 530 580 110 660 700
Eagle
Gypsum, Blo April-July255 265 290 87 315 330
June-July165 173 198 92 225 240
Colorado
Dotsero, Nr April-July1300 1350 1410 101 1500 1600
June-July750 800 860 102 950 1050
Frying Pan
Ruedi Res, Basalt, Nr April-July110 115 125 90 135 140
June-July66 71 81 91 91 96
Roaring Fork
Glenwood Springs April-July580 615 650 94 690 720
June-July390 425 460 101 500 530
Colorado
Glenwood Springs, Blo April-July1900 2000 2070 98 2250 2350
June-July1150 1250 1320 102 1500 1600
Cameo, Nr April-July2000 2140 2220 94 2390 2550
June-July1210 1350 1430 101 1600 1760
Plateau Ck
Cameo, Nr April-July60 65 75 60 80 90
June-July15 20 30 61 35 45
Colorado
Cisco, Nr April-July3900 4100 4310 97 4500 4700
June-July1990 2190 2400 103 2590 2790
Lake Powell, Glen Cyn Dam, At April-July7400 8000 8300 116 8600 9200
June-July3410 4010 4310 115 4610 5210


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 Res April-July103 106 109 110 114 119
June-July61 64 67 108 72 77
Almont April-July167 171 175 113 181 187
June-July95 99 103 110 109 115
East
Almont April-July215 220 225 124 230 240
June-July116 121 126 119 131 141
Gunnison
Gunnison, Nr April-July440 445 455 123 470 480
June-July235 240 250 116 265 275
Tomichi Ck
Gunnison April-July100 105 109 147 113 116
June-July42 47 51 138 55 58
Lake Fork
Gateview April-July127 133 138 112 143 151
June-July85 91 96 119 101 109
Gunnison
Blue Mesa Res April-July810 825 840 124 855 880
June-July420 435 450 118 465 490
Morrow Point Res April-July875 890 905 122 920 945
June-July455 470 485 120 500 525
Crystal Res April-July940 980 995 119 1010 1040
June-July490 530 545 121 560 585
Muddy Ck
Paonia Res, Bardine, Nr March-June64 66 68 71 70 73
April-July58 60 62 64 64 67
June-June11 13 15 65 17 20
June-July15 17 19 66 21 24
Nf Gunnison
Somerset, Nr April-July245 250 255 86 260 265
June-July83 89 93 82 98 103
Surface Ck
Cedaredge April-July12.1 12.6 13.1 78 15.6 16.1
June-July3 3.5 4 53 6.5 7
Uncompahgre
Ridgway Res April-July91 95 98 97 104 109
June-July59 63 66 102 72 77
Colona April-July123 126 131 96 137 146
June-July75 78 83 102 89 98
Delta April-July108 111 115 102 121 131
June-July52 55 59 104 65 75
Gunnison
Grand Junction, Nr April-July1540 1550 1570 106 1610 1640
June-July740 755 775 112 815 840


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-July275 280 285 116 290 300
June-July84 90 95 103 100 111
Mcphee Res April-July310 320 325 110 330 340
June-July87 94 100 103 107 117
San Miguel
Placerville, Nr April-July114 118 121 95 126 132
June-July67 71 74 99 79 85
Dolores
Cisco, Nr April-July510 515 520 92 535 550
June-July180 185 189 103 205 220

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 451.6 124 92 437.3 120 363.6 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 9.4 106 103 8.7 97 8.9 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 82.5 113 85 86.1 118 73.0 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 67.2 112 102 67.0 112 59.9 66.0
untitled Blue
Dillon Res 232.6 100 92 235.8 101 232.7 254.0
Green Mtn Res 90.8 101 62 97.0 108 89.8 146.9
untitled Homestake Ck
Homestake Res 29.7 120 69 38.2 154 24.8 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 78.2 100 77 76.9 99 78.0 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 33.9 110 103 34.3 111 30.8 32.9
untitled Taylor
Taylor Park Res 84.3 113 79 76.7 103 74.7 106.2
untitled Gunnison
Blue Mesa Res 596.8 104 72 571.6 99 575.3 829.5
Morrow Point Res 108.8 96 93 99.0 87 113.2 117.0
Crystal Res 19.0 114 109 17.0 102 16.7 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 12.0 77 72 7.1 46 15.7 16.7
untitled Uncompahgre
Ridgway Res 64.8 92 78 61.8 87 70.7 83.0
untitled Dolores
Mcphee Res 367.1 106 96 366.5 105 347.8 381.1
untitled
TOTAL 2328.7 107 83 2280.8 105 2175.6 2792.1
Colorado
Lake Powell 13667.1 75 56 12123.2 67 18186.3 24322.0
untitled
TOTAL 13667.1 75 56 12123.2 67 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: Brenda Alcorn, Greg Smith