Bighorn River Basin (4)
January 1998

Snow
The Nowood drainage is 58 percent of last year and 74 percent of average SWE for January 1. The Greybull River drainage SWE is about 137 percent of average (77 percent of last year). Shell Creek SWE is about 94 percent of average (79 % of last year). The basin SWE, as a whole, is currently 96 percent the January 1average (73 % of 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 108 percent of average. December precipitation was 109 percent of the monthly average. Thermopolis was the highest reporting station at 500 percent of the December average and Rairden was the low at 8 percent of average. Year-to-date precipitation is about 108 percent of normal; that is about 92 percent of last year.

Reservoir
Boysen Reservoir is currently storing 569,100 acre feet (93 percent of average). Bighorn Lake is now at 108 percent of average (964,800 acre feet). Boysen is currently storing 102 percent of last year at this time and Big Horn Lake is storing 108 percent of last years volume.

Streamflow
The remaining of the runoff season (Apr - Sep) should yield below average runoff. The Wind River below Boysen is forecast to yield 655,000 acre feet (81 percent of average); the Nowood River near Ten Sleep should yield near 45,000 acre feet (78 percent of normal); the Greybull River near Meeteese should yield 170,000 acre feet (85 percent of average); Shell Creek near Shell should yield 67,000 acre feet (89 percent of average) and the Bighorn River at Kane should yield 925,000 acre feet (82 percent of average). 

==================================================================================================================================
                                                       BIGHORN RIVER BASIN
                                               Streamflow Forecasts - January 1, 1998
==================================================================================================================================
                                              |  <<====== 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       303       513    |      655        81    |       797      1007            809
                                                                    |                       |
NOWOOD RIVER near Tensleep           APR-SEP        27        38    |       45        78    |        52        63             58
                                                                    |                       |
GREYBULL RIVER at Meeteetse          APR-SEP       120       150    |      170        85    |       190       220            201
                                                                    |                       |
SHELL CREEK near Shell               APR-SEP        56        63    |       67        89    |        71        78             75
                                                                    |                       |
BIGHORN RIVER at Kane (2)            APR-SEP       416       719    |      925        82    |      1131      1434           1124
                                                                    |                       |
==================================================================================================================================
                           BIGHORN RIVER BASIN                          |                   BIGHORN RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 1998
==================================================================================================================================
                                      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    569.1    556.7    613.5 |   NOWOOD RIVER                2        58        74
                                                                        |
BIGHORN LAKE                          1356.0    964.8    894.3    891.8 |   GREYBULL RIVER              2        77       137
                                                                        |
                                                                        |   SHELL CREEK                 3        79        94
                                                                        |
                                                                        |   BIGHORN (Boysen-Bighorn)    7        73        96
                                                                        |
==================================================================================================================================
 * 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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