Shoshone and Clarks Fork River Basin (5)
February 2002

Snow
Snow Water Equivalent (SWE) is 75 percent of the February average (171 percent of last year) in the Shoshone River basin. The Clarks Fork River basin SWE is 79 percent of average (166 percent of last year). For more information see the Basin Summary of Snow Course Data at the beginning of this report.

Precipitation
Precipitation for the month of January was 91 percent of normal. Monthly percentages range from 0 to 138 percent of average. The basin year-to-date precipitation is now 82 percent of average (141 percent of last year). Year-to-date percentages range from 63 to 88 percent of average.

Reservoir
Current storage in Buffalo Bill Reservoir is 96 percent of average (76 percent of last year's storage) the reservoir is about 43 percent of capacity. Currently, about 280,200 acre-feet are stored in the reservoir compared to 370,200 acre feet last year. Detailed reservoir data is shown on the following page and on the reservoir storage summary at the beginning of this report.

Streamflow
The fifty percent yield (April through September period) for North Fork Shoshone River at Wapiti is expected to be 345,000 acre-feet (66 percent of average). South Fork of the Shoshone River near Valley is estimated to yield of 150,000 acre-feet (57 percent of average), and South Fork above Buffalo Bill Reservoir is expected to be 115,000 acre-feet (51 percent of average). At the Buffalo Bill Reservoir, the fifty percent chance yield for the Shoshone River is expected to be about 515,000 acre- feet (64 percent of average). The fifty-percent chance yield for the Clarks Fork of the Yellowstone near Belfry, Montana is expected to be about 390,000 acre-feet (66 percent of average).

==================================================================================================================================
                                               SHOSHONE & CLARKS FORK RIVER BASINS
                                               Streamflow Forecasts - January 1, 2002
==================================================================================================================================
                                              |  <<====== 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)
====================================================================|=======================|=====================================
NF SHOSHONE RIVER at Wapiti          APR-SEP       243       286    |      315        61    |       344       387            520
                                                                    |                       |
SF SHOSHONE RIVER nr Valley          APR-SEP        72       108    |      132        50    |       156       192            265
                                                                    |                       |
SF SHOSHONE RIVER abv Buffalo Bill   APR-SEP        26        77    |      112        50    |       147       198            225
                                                                    |                       |
BUFFALO BILL DAM Inflow (2)          APR-SEP       280       408    |      495        62    |       582       710            805
                                                                    |                       |
CLARKS FORK RIVER nr Belfry          APR-SEP       291       359    |      405        68    |       451       519            595
                                                                    |                       |
==================================================================================================================================
                   SHOSHONE & CLARKS FORK RIVER BASINS                  |           SHOSHONE & CLARKS FORK RIVER BASINS
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 2002
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
BUFFALO BILL                           646.6    234.4    379.0    299.0 |   SHOSHONE RIVER              6       122        70
                                                                        |
                                                                        |   CLARKS FORK in WY           7       127        78
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual volume will exceed the volumes in the table.

(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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