Bighorn River Basin
February 1997

Snow
All drainage's in the basin are above average at this time. The Greybull River drainage is very near last years SWE, with 164 percent of average. Shell Creek SWE is lower, at only 18 percent above average. The basin SWE, as a whole, is currently 123 percent of February 1 average. SWE for the entire basin is 8 percent ahead of February 1996 (last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
Precipitation, for the water year, has been good and is now 127 percent of average. Only 1 site, Sunshine (47 percent), is below average. December precipitation was over 130 percent of the monthly average. Worland reported 273 percent of the January average.

Reservoir
Reservoir storage is good in the basin with Bighorn Lake at 98 percent of average and Boysen at 93 percent. Boysen is currently storing 542,900 acre feet and Bighorn Lake is at 826,400. This is just slightly less than what was being stored last year at this time.

Streamflow
All forecast points are predicted to be average to well above average. The Wind River below Boysen is forecast to yield 1,300,000 acre feet (161 percent of average); the Nowood River near Ten Sleep should yield near 68,000 acre feet (117 percent of normal); the Greybull River near Meeteese should yield 225,000 acre feet (112 percent of average); Shell Creek near Shell should yield 88,000 acre feet (117 percent of average) and the Bighorn River at Kane should yield 1,575,000 acre feet (140 percent of average). 

==================================================================================================================================
                                                       BIGHORN RIVER BASIN
                                               Streamflow Forecasts - February 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)
====================================================================|=======================|=====================================
WIND RIVER below Boysen (2)          APR-SEP       978      1170    |     1300       161    |      1430      1622            809
                                                                    |                       |
NOWOOD RIVER near Tensleep           APR-SEP        24        50    |       68       117    |        86       112             58
                                                                    |                       |
GREYBULL RIVER at Meeteetse          APR-SEP       181       207    |      225       112    |       243       269            201
                                                                    |                       |
SHELL CREEK near Shell               APR-SEP        77        83    |       88       117    |        93        99             75
                                                                    |                       |
BIGHORN RIVER at Kane (2)            APR-SEP      1093      1380    |     1575       140    |      1770      2057           1124
                                                                    |                       |
==================================================================================================================================
                           BIGHORN RIVER BASIN                          |                   BIGHORN RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 1997
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
BOYSEN                                 596.0    542.9    572.4    580.7 |   NOWOOD RIVER                5       117       119
                                                                        |
BIGHORN LAKE                          1356.0    826.4    848.9    839.2 |   GREYBULL RIVER              2       102       164
                                                                        |
                                                                        |   SHELL CREEK                 4       104       118
                                                                        |
                                                                        |   BIGHORN (Boysen-Bighorn)   11       108       124
                                                                        |
==================================================================================================================================
 * 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.
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