Upper Bear River Basin (13)
April 1998

Snow
Snow water equivalent (SWE), at data sites in the Bear River above the Idaho State Line, is 89 percent of average (67 percent of last year). SWE for the Bear River in Utah is estimated to be 85 percent of average; that is about 72 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 90 percent of average (66 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 March was 160 percent of average for the two reporting stations; this is 145 percent of the previous March. The year-to-date precipitation, for the basin, is 96 percent of average; this is 78 percent of last year's amount.

Reservoir
Woodruff Narrows reservoir is currently storing 46,000 acre feet compared to 57,300 acre feet 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 107,000 acre feet; that is 85 percent of average. The Thomas Fork drainage is estimated to yield 29,000 acre feet or 81 percent of normal for the April-September period. The 50 percent chance yield for Smiths Fork near Border is about 105,000 acre feet (89 percent of normal) for the April-September period. The Bear River near Woodruff is expected to yield 127,000 acre feet, about 85 percent of normal for the April-July period. 

==================================================================================================================================
                                                      UPPER BEAR RIVER BASIN
                                               Streamflow Forecasts - April 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              APR-SEP        75        89    |      100        85    |       113       134            118
                                                                    |                       |
THOMAS FK nr WY-ID State Line        APR-SEP      16.8        22    |       27        75    |        33        44             36
                                                                    |                       |
Bear R nr UT-WY State Line           APR-SEP        84        97    |      107        85    |       118       137            126
                                                                    |                       |
BEAR R nr Woodruff, UT               APR-SEP        78       106    |      131        85    |       162       220            154
                                                                    |                       |
==================================================================================================================================
                         UPPER BEAR RIVER BASIN                         |                 UPPER BEAR RIVER BASIN
             Reservoir Storage (1000 AF) - End of March                 |        Watershed Snowpack Analysis - April 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     46.0     57.3      --- |   UPPER BEAR RIVER in Utah    5        72        85
                                                                        |
                                                                        |   SMITHS & THOMAS FORKS       4        66        90
                                                                        |
                                                                        |   BEAR RIVER abv ID line      9        67        89
                                                                        |
==================================================================================================================================
 * 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.
To April 1998 Basin Outlook Report Contents Page