Upper Bear River Basin (13)
May 1999

Snow
Snow water equivalent (SWE), at snow courses in the Bear River above the Idaho State Line, is 122 percent of average (127 percent of last year). SWE for the Bear River in Utah is estimated to be 124 percent of average; that is about 108 percent of last year at this time. SWE in the Wyoming portion of the Bear River drainage (Smiths and Thomas Forks) is estimated at 121 percent of average (138 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 163 percent of average for the 2 reporting stations; this is 189 percent of the previous April. The monthly percentages range from 32 to 271 percent of average. The year-to-date precipitation, for the basin, is 108 percent of average; this is 113 percent of last year's amount. Year-to-date percentages range from 106 to 110 percent of average.

Reservoir
Woodruff Narrows reservoir is currently storing 57,300 acre feet compared to 57,300 acre feet this time last year. There is no average established for Woodruff Narrows. The total capacity of the reservoir is 57,300 acre-feet.

Streamflow
The 50 percent chance stream flow yields are expected to be near average in the Bear River drainage. The Bear River near the Utah-Wyoming State Line is expected to yield about 122,000 acre feet; that is 102 percent of average for the May through September period. The Thomas Fork drainage is estimated to yield 31,000 acre-feet or 103 percent of normal for the May-September period. The 50 percent chance yield for Smiths Fork near Border is about 118,000 acre-feet (108 percent of normal) for the May-September period. The Bear River near Woodruff is expected to yield about 130,000 acre-feet, about 103 percent of normal for the May-July period. 

==================================================================================================================================
                                                      UPPER BEAR RIVER BASIN
                                               Streamflow Forecasts - May 1, 1999
==================================================================================================================================
                                              |  <<====== 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        93       107    |      118       108    |       130       150            109
                                                                    |                       |
THOMAS FK nr WY-ID State Line (Disc. MAY-SEP      19.7        26    |       31       103    |        37        49             30
                                                                    |                       |
Bear R nr UT-WY State Line           APR-SEP       111       120    |      126       100    |       133       143            126
                                     MAY-SEP       107       115    |      122       102    |       129       140            120
                                                                    |                       |
BEAR R nr Woodruff, UT               APR-JUL        98       127    |      150       101    |       178       229            149
                                     MAY-JUL        83       109    |      130       103    |       155       202            126
                                                                    |                       |
==================================================================================================================================
                         UPPER BEAR RIVER BASIN                         |                 UPPER BEAR RIVER BASIN
             Reservoir Storage (1000 AF) - End of April                 |        Watershed Snowpack Analysis - May 1, 1999
==================================================================================================================================
                                      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       108       124
                                                                        |
                                                                        |   SMITHS & THOMAS FORKS       4       138       121
                                                                        |
                                                                        |   BEAR RIVER abv ID line      9       127       122
                                                                        |
==================================================================================================================================
 * 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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