Bighorn River Basin
January 1997

Snow
All drainages in the basin are above average at this time. The Greybull River drainage is very near last years SWE, with 178 percent of average. Shell Creek SWE is lower, at only 18 percent above average. The basin SWE, as a whole, is currently 131 percent of January 1 average. SWE for the entire basin is 9 percent ahead of January 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 125 percent of average. Only 2 sites, Worland (62 percent) and Sunshine (50 percent), are below average. December precipitation was over 160 percent of the monthly average. Kirwin reported 367 percent of the December average.

Reservoir
Reservoir storage is good in the basin with Bighorn Lake at 100 percent of average and Boysen at 91 percent. Boysen is currently storing 556,700 acre feet and Bighorn Lake is at 894,300. This is just slightly less than what was being stored last year at this time.

Streamflow
All forecast points are predicted at average to well above average. The Wind River below Boysen is forecast to yield 178 percent of average (1,440,000 acre feet) and the Nowood River could see the lowest percent of average flow at 103 percent. Stream yield, based on a 50 percent probability, is 1,440,000 acre feet (178 percent of average) for Wind River below Boysen, 60,000 acre feet (103 percent of normal) for Nowood River near Ten Sleep, 225,000 acre feet (112 percent of average) for Greybull River near Meeteesee, 90,000 acre feet (120 percent of average) for Shell Creek near Shell, and 1,690,000 acre feet (150 percent of average) for the Bighorn River at Kane. 

==================================================================================================================================
                                                       BIGHORN RIVER BASIN
                                               Streamflow Forecasts - January 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      1088      1298    |     1440       178    |      1582      1792            809
                                                                    |                       |
NOWOOD RIVER near Tensleep           APR-SEP        42        53    |       60       103    |        67        78             58
                                                                    |                       |
GREYBULL RIVER at Meeteetse          APR-SEP       175       205    |      225       112    |       245       275            201
                                                                    |                       |
SHELL CREEK near Shell               APR-SEP        79        86    |       90       120    |        94       101             75
                                                                    |                       |
BIGHORN RIVER at Kane (2)            APR-SEP      1281      1484    |     1690       150    |      1896      2102           1124
                                                                    |                       |
==================================================================================================================================
                           BIGHORN RIVER BASIN                          |                   BIGHORN RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 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    556.7    588.1    613.5 |   NOWOOD RIVER                2       121       130
                                                                        |
BIGHORN LAKE                          1356.0    894.3    912.2    891.8 |   GREYBULL RIVER              2       106       178
                                                                        |
                                                                        |   SHELL CREEK                 3       106       118
                                                                        |
                                                                        |   BIGHORN (Boysen-Bighorn)    7       109       131
                                                                        |
==================================================================================================================================
 * 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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