JUNE 1, 2004 SUMMARY

Nearly all of the snowpack has been depleted over the Eastern Great Basin as of June 1. May

precipitation was below average in the North and much below average in the South. As a result,

the April-July runoff forecasts decreased slightly in most basins. Forecasts range mostly from 25

to 60 percent of the 1971-2000 average in the Great Salt Lake Basin and 25 to 50 percent in the

Sevier Lake Basin.

APRIL - JULY VOLUME FORECASTS

9 5 % 9 5 %

7 0 % 6 5 %

8 0 % 8 5 %

5 0 % 4 5 %4 5 % 4 5 %4 5 %4 0 %

0 %

2 0 %

4 0 %

6 0 %

8 0 %

1 0 0 %

G r e a t S a l t L a k e B a s i n S e v i e r L a k e B a s i n

P e r c e n t o f' 7 1 - ' 0 0A v e r a g e

J a n . F e b . M a r . A p r . M a y J u n .

INSIDE Summary 1 Great Salt Lake Basin 2 Sevier Basin 3 Specific Site Forecasts 4,5 EOM Reservoir Contents 6 Monthly Streamflows 7 Precipitation Maps 8,9 Additional Information 10

NOAA

WATER SUPPLY OUTLOOKfor the

EASTERN GREAT BASIN

NATIONAL WEATHER SERVICE, SALT LAKE CITY, UT

COLORADO BASINRIVER FORECAST CENTER

Colorado Basin River Forecast Center - National Weather Service Page 2

April-July streamflow forecasts for the Great Salt Lake Basin are as follows:

GREAT SALT LAKE BASIN

The June 1 water supply outlook is for much below average runoff in the Great Salt Lake Basin.

Bear River: Much Below Average Weber River: Much Below Average Utah Lake: Much Below Average Six Creeks: Much Below Average

BASIN CONDITIONS - JUNE 1, 2004

* Percent usable capacity, not percent average contents. Specific site forecasts are listed beginning on page 4.

80%90%

10%

75%

40%

0%

20%

40%

60%

80%

100%

MayPrecipitation

Water YearPrecipitation

Snow WaterEquivalent

MayStreamflow

ReservoirContents *

Percent of'71 - '00Average

Bear 40%

Weber 35%

Utah Lk 50%

Six Creeks 45%

Colorado Basin River Forecast Center - National Weather Service Page 3

SEVIER LAKE BASIN

The June 1 water supply outlook is for much below average April-July runoff volumes in the Sevier Lake Basin.

April-July streamflow forecasts for the Sevier Lake Basin are as follows:

Sevier River: Much Below Average

* Percent usable capacity, not percent average contents. Specific site forecasts are listed beginning on page 5.

50%

90%

0%

55%

25%

0%

20%

40%

60%

80%

100%

MayPrecipitation

Water YearPrecipitation

Snow WaterEquivalent

MayStreamflow

ReservoirContents *

Percent of'71 - '00Average

Sevier 40%

BASIN CONDITIONS - JUNE 1, 2004

Colorado Basin River Forecast Center - National Weather Service Page 4

SPECIFIC SITE FORECASTS

Great Salt Lake Basin: April through July volume (kaf) forecasts (except where noted).

Stream Station Most Percent Reas. Reas.Probable Avg. Max Min

BEAR UTAH-WYOMING STATE LINE, NR 47 42 61 41WOODRUFF NARROWS RES 35 26 66 27MONTPELIER, NR, STEWART DAM, B 15 6 31 5

BIG CK RANDOLPH, NR 0.88 18 1.19 0.57SMITHS FORK BORDER, NR 46 45 52 40LOGAN LOGAN, NR, STATE DAM, ABV 66 52 73 59BLACKSMITH FORK HYRUM, NR, UP&L DAM, ABV 17.5 36 20 15SMITH AND MOREHOUSE CK OAKLEY, NR 17.4 51 20 14.2WEBER OAKLEY, NR 57 46 69 45

ROCKPORT RES, WANSHIP, NR 49 37 63 35COALVILLE, NR 46 34 61 31ECHO RES, ECHO, AT 62 35 91 33GATEWAY 110 31 167 53

CHALK CK COALVILLE 14 31 25 3.3LOST CK LOST CK RES, CROYDON, NR 6.9 39 8.5 5.4EAST CANYON CK EAST CANYON RES, MORGAN, NR 10.2 33 13.3 7.5SF OGDEN HUNTSVILLE, NR 28 44 34 22OGDEN PINEVIEW RES, OGDEN, NR 48 36 67 29WHEELER CK HUNTSVILLE, NR 1.6 25 1.9 1.3SPANISH FORK CASTILLA, NR 31 40 67 25PROVO WOODLAND, NR 59 57 77 41

HAILSTONE, NR 59 54 85 33DEER CK RES 72 57 99 45

AMERICAN FORK AMERICAN FORK, NR, UP PWRPLNT, 16 50 21 11.2JORDAN UTAH LAKE, PROVO, NR 160 49 235 84LITTLE COTTONWOOD CK SALT LAKE CITY, NR 25 62 29 21BIG COTTONWOOD CK SALT LAKE CITY, NR 23 61 29 17.4CITY CK SALT LAKE CITY, NR 4.2 48 7.1 2.5EMIGRATION CK SALT LAKE CITY, NR 1.7 38 3.8 1MILL CK SALT LAKE CITY, NR 2.5 36 4.4 1.5DELL FK LITTLE DELL RES 2.5 37 3.9 1.2PARLEYS CK SALT LAKE CITY, NR 6.2 37 11.4 4VERNON CK VERNON, NR 0.42 28 0.58 0.3S WILLOW CK GRANTSVILLE, NR 1.5 47 1.9 1.1SETTLEMENT CK TOOELE, NR 0.71 36 0.77 0.65

Colorado Basin River Forecast Center - National Weather Service Page 5

Sevier Lake Basin: April through July volume (kaf) forecasts (except where noted).

Stream Station Most Percent Reas. Reas.Probable Avg. Max Min

SEVIER HATCH 24 44 40 15KINGSTON, NR 37 42 68 20PIUTE RES, MARYSVALE, NR 47 37 104 18.9VERMILLION DAM 71 41 142 40SIGURD, NR 73 39 168 40GUNNISON, NR, SAN PITCH, BLO 104 37 320 65

EF SEVIER KINGSTON, NR 17 45 36 14CLEAR CK SEVIER, NR, DIV, ABV 10 45 19.5 4.1SALINA CK T SALINA MB 0 0 0CHICKEN CK LEVAN, NR 1.1 24 1.47 0.79OAK CK OAK CITY, NR, LITTLE CK, ABV 0.68 42 0.97 0.44BEAVER BEAVER, NR 13.3 49 15.5 11.3

MINERSVILLE RES, MINERSVILLE, 2.3 14 6.7 0.2COAL CK CEDAR CITY, NR 9.6 50 11 9

T Categorical Forecast - Current regulations allow for discontinuance of a streamflow volume forecast when observations at the point have not been taken or recorded for 5 years or longer. Recognizing the importance to the user, the NWS and NRCS have often continued to provide fore-casts long after observations have ceased. Forecasters will now have the option to express these forecasts categorically (e.g. instead of issuing a forecast of 77 percent of average, the forecast would simply be “below average”). Specifically, the categories are:

MA - much above normal (greater than 130 percent of normal)

AN - above normal (111– 130 percent of normal)

NN - near normal (90-110 percent of normal)

BN - below normal (70-89 percent of normal)

MB - much below normal (less than 70 percent of normal)

Colorado Basin River Forecast Center - National Weather Service Page 6

END OF MONTH RESERVOIR CONTENTS

Percent of Usable Capacity

62%39%

0%25%

50%

75%

100%

2003 2004

RESERVOIR Usable EOM Usable Percent Usable(vol. in 1000 ac-ft) Capacity Contents Capacity (%)

Bear Lake 1302 101.9 8Causey 7.1 7 99Jordanelle 311 267.6 86Deer Creek 149.7 82.5 55East Canyon 49.5 40.4 82Echo 73.9 58.3 79Gunnison 20.3 3.9 19Hyrum 15.3 15.1 99Lost Creek 22.5 9.4 42Minersville 23.3 5.5 24Otter Creek 52.5 19.9 38Pine View 110.1 99.3 90Piute 71.8 12.1 17Rockport 60.9 48.4 79Sevier bridge 236 51 22* Utah Lake 870.9 472.2 54Willard 215 92.8 43Woodruff Narrows 55.8 31 56TOTAL 3647.6 1418.3 39

Flaming Gorge 3749 2595.1 69Lake Powell 24322 10566.3 43Moon Lake 36 16.9 47Red Fleet 25.7 missing missingScofield 65.8 missing missingStarvation 165.3 151.7 92Steinaker 34.4 missing missingStrawberry 1105.9 802.8 73Upper Stillwater 32.5 15 46

* Usable capacity taken at compromise Total does not include missing site usable capacities

Colorado Basin River Forecast Center - National Weather Service Page 7

MONTHLY STREAMFLOWS

2004 Water Year 2003 Water Year 30 Year Average 2004 Forecast

Sevier - Hatch:

Logan - Logan, nr, State Dam, abv:

Weber Oakley, nr:

0

10

20

30

40

50

60

Jan* Feb* Mar. Apr. May Jun. Jul.

1000Ac-ft

0

10

20

30

40

50

Jan. Feb. Mar. Apr. May Jun. Jul.

1000Ac-ft

0

5

10

15

20

25

Jan. Feb. Mar. Apr. May Jun. Jul.

1000Ac-ft

* observed data unavailable

Colorado Basin River Forecast Center - National Weather Service Page 8

Colorado Basin River Forecast Center - National Weather Service Page 9

Colorado Basin River Forecast Center - National Weather Service Page 10

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 pr o-gresses, a greater portion of the future hydrologic and climatic uncertainty becomes known and monthly forecasts become more accurate.

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. How-ever, 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, National Weather Service. It represents a coordinated effort between the Na-tional Weather Service, Natural Resources Conservation Service, Bureau of Reclamation, U.S. Geological Survey and local water di strict managers.

DEFINITIONS:

Acre-Foot: The volume equal to one acre covered one foot deep (43,560 cubic feet). Average:

The arithmetic mean. The sum of the values divided by the number of values. Categories:

Much above Average Above Average Near Average Below Average Much Below Average Greater than 130% 111-130% 90-110% 70-89% Less than 70% Forecast Period:

The period from April 1 through July 31. Median:

The middle value. One half of the observed values are higher and half of the values are lower than this. Most Probable Forecast:

Given the current hydrometeorological conditions to date, this is the best estimate of what the runoff volume will be this season. Reasonable Maximum Forecast:

Given the current hydrometeorological conditions, the seasonal runoff that has a ten percent (10%) chance of being exceeded. Reasonable Minimum Forecast:

Given the current hydrometeorological conditions, the seasonal runoff that has a ninety percent (90%) chance of being exceeded. Water Year:

The period from October 1 through September 30. 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 Cente r, National Weather Service

2242 W. North Temple · Salt Lake City, UT 84116 · (801) 524-5130 · http://www.cbrfc.gov