Upper Bear River Basin (13)
May 1998

Snow
Snow water equivalent (SWE), at snow courses in the Bear River above the Idaho State Line, is 97 percent of average (62 percent of last year). SWE for the Bear River in Utah is estimated to be 114 percent of average; that is about 73 percent of last year at this time. SWE in the Wyoming portion of the Bear River drainage (Smiths and Thomas Forks) is estimated to be 89 percent of average (59 percent of last year at this time.). See the Basin Summary of Snow Course Data at the beginning of this report for more detailed information.

Precipitation
Precipitation for the month of April was 84 percent of average for the two reporting stations; this is 40 percent of the previous April. The year-to-date precipitation, for the basin, is 105 percent of average; this is 76 percent of last year's amount.

Reservoir
Woodruff Narrows reservoir is currently storing 57,300 acre feet compared to same amount last year. The total capacity of the reservoir is 57,300 acre feet.

Streamflow
The 50 percent chance stream flow yields are expected to be below average in the Bear River drainage. The Bear River near the Utah-Wyoming State Line is expected to yield 109,000 acre feet; that is 91 percent of average for the May to September period. The Thomas Fork drainage is estimated to yield 24,000 acre feet or 80 percent of normal for the May-September period. The 50 percent chance yield for Smiths Fork near Border is about 98,000 acre feet (90 percent of normal) for the May-September period. The Bear River near Woodruff is expected to yield 115,000 acre feet, about 91 percent of normal for the May-July period. 

==================================================================================================================================
                                                      UPPER BEAR RIVER BASIN
                                               Streamflow Forecasts - May 1, 1998
==================================================================================================================================
                                              |  <<====== Drier ======  Future Conditions  =======  Wetter =====>>  |             
                                              |                                                                     |
  Forecast Point                     Forecast |  ==================== Chance Of Exceeding * ======================  |
                                      Period  |    90%       70%    |  50% (Most Probable)  |      30%       10%    |  30-Yr Avg.
                                              | (1000AF)  (1000AF)  |   (1000AF)  (% AVG.)  |    (1000AF)  (1000AF) |    (1000AF)
====================================================================|=======================|=====================================
SMITHS FK nr Border, WY              MAY-SEP        77        89    |       98        90    |       108       124            109
                                                                    |                       |
THOMAS FK nr WY-ID State Line        MAY-SEP      15.3        20    |       24        80    |        29        38             30
                                                                    |                       |
Bear R nr UT-WY State Line           APR-SEP       101       109    |      115        91    |       121       131            126
                                     MAY-SEP        95       103    |      109        91    |       115       125            120
                                                                    |                       |
BEAR R nr Woodruff, UT               APR-SEP        90       117    |      139        90    |       165       214            154
                                     MAY-JUL        74        96    |      115        91    |       138       179            126
                                                                    |                       |
==================================================================================================================================
                         UPPER BEAR RIVER BASIN                         |                 UPPER BEAR RIVER BASIN
             Reservoir Storage (1000 AF) - End of April                 |        Watershed Snowpack Analysis - May 1, 1998
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
WOODRUFF NARROWS                        57.3     57.3     57.3      --- |   UPPER BEAR RIVER in Utah    5        73       114
                                                                        |
                                                                        |   SMITHS & THOMAS FORKS       4        59        89
                                                                        |
                                                                        |   BEAR RIVER abv ID line      9        62        97
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual volume will exceed the volumes in the table.

The average is computed for the 1961-1990 base period.

(1) - The values listed under the 10% and 90% Chance of Exceeding are actually 5% and 95% exceedance levels.                  
(2) - The value is natural volume - actual volume may be affected by upstream water management.
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