Little Snake River Basin
May 1997

Snow
Snowfall has been good across the basin this year. Snow accumulation was above average last month, which raised the year to date percent of average SWE. Currently the basin is 131 percent of average for the year and 11 percent ahead of last year at this time. All of the reporting sites are above average at this time. For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation across the basin is also above average. The Little Snake River basin water-year-to-date precipitation is currently standing at 115 percent of average (6 percent more than last year). April precipitation figures ran about 8 percent above average for the 5 reporting stations.

Streamflow forecasts
Stream yield, based on the 50 percent probability, is forecast to be 48 percent above average near Slater and 52 percent above average near Dixon. Near Slater the Little Snake should yield about 230,000 acre feet and near Dixon it should be about 500,000 acre feet.
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                                                     LITTLE SNAKE RIVER BASIN
                                               Streamflow Forecasts - May 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)
====================================================================|=======================|=====================================
LITTLE SNAKE R nr Slater             APR-JUL       199       217    |      230       148    |       243       261            155
                                                                    |                       |
LITTLE SNAKE R nr Dixon              APR-JUL       394       457    |      500       152    |       543       606            329
                                                                    |                       |
==================================================================================================================================
                        LITTLE SNAKE RIVER BASIN                        |                LITTLE SNAKE RIVER BASIN
             Reservoir Storage (1000 AF) - End of April                 |        Watershed Snowpack Analysis - May 1, 1997
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
                                                                        |   LITTLE SNAKE RIVER          8       111       131
                                                                        |
==================================================================================================================================
 * 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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