Upper Bear River Basin
April 1997

Snow
Snow water equivalent (SWE) at data sites in the Bear River above the Idaho State Line is 32 percent above average (8 percent less than last month). The Bear River in Utah measured about 18 percent more SWE than average; that is about 10 percent less than last year at this time. SWE In the Wyoming portion of the Bear River drainage (Smiths and Thomas Forks) is estimated to be about 36 percent of average (about 18 percent more than last year). 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 about 4 percent above average for the two reporting stations; this is about 8 percent less than March of last year. The year-to-date precipitation figure for the basin is 139 percent of average; this is about 21 percent more than last year.

Reservoir
Woodruff Narrows Reservoir presently contains about 57,300 acre feet of water; that is compared to 53,000 acre feet at this time last year.

Streamflow
The 50 percent chance April - September stream flow yields are expected to be much above average in the Bear River drainage. The Bear River at the Utah State Line is expected to yield 170,000 acre feet; that is about 35 percent more than average. The Thomas Fork drainage is estimated to yield 50,000 acre feet or 39 percent more than normal for the April - September period. The 50 percent chance yield for Smiths Fork near Border is about 170,000 acre feet (44 percent more than normal) for the April - September period. The Bear River near Woodruff is expected to yield about 205,000 acre feet, about 38 percent more than normal for the April-July period. 

==================================================================================================================================
                                                      UPPER BEAR RIVER BASIN
                                               Streamflow Forecasts - April 1, 1997
==================================================================================================================================
                                              |  <<====== 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 FORK nr Border, WY            APR-SEP       144       159    |      170       144    |       181       196            118
                                                                    |                       |
THOMAS FK nr WY-ID State Line        APR-SEP        31        41    |       50       139    |        60        80             36
                                                                    |                       |
BEAR R nr UT-WY State Line           APR-SEP       131       153    |      170       135    |       189       220            126
                                                                    |                       |
BEAR R nr Woodruff (2)               APR-JUL       105       164    |      205       138    |       246       305            149
                                                                    |                       |
==================================================================================================================================
                         UPPER BEAR RIVER BASIN                         |                 UPPER BEAR RIVER BASIN
             Reservoir Storage (1000 AF) - End of March                 |        Watershed Snowpack Analysis - April 1, 1997
==================================================================================================================================
                                      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     53.0      --- |   UPPER BEAR RIVER in Utah    5        90       118
                                                                        |
                                                                        |   SMITHS & THOMAS FORKS       4       118       136
                                                                        |
                                                                        |   BEAR RIVER abv ID line     11       108       132
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual flow 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 flow - actual flow may be affected by upstream water management.
To April 1997 Basin Outlook Report Contents Page