Bighorn River Basin (4)
January 2002

Snow
Snowpack in this basin is well below average for this time of year. The Nowood drainage SWE is 69 percent of average (101 percent of last year). Greybull River SWE is 51 percent of average (105 percent of last year). Shell Creek SWE is 85 percent of average (116 percent of last year). The basin SWE, as a whole, is currently 74 percent of average (111 percent of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
December precipitation was 44 percent of the monthly average (56 percent of last year). Sites ranged from 7 to 139 percent of average for the month. Year-to-date precipitation is 82 percent of normal; that is 114 percent of last year at this time. Year to date percentages, from the 10 reporting stations, range from 58 to 106.

Reservoir
Boysen Reservoir is currently storing 82,800-acre feet (13 percent of average). Bighorn Lake is now at 83 percent of average (753,100-acre feet). Boysen is currently storing 85 percent of last year at this time and Big Horn Lake is storing 62 percent of last year's volume.

Streamflow
The 50 percent chance April through September runoff is anticipated to be below normal. The Boysen Reservoir inflow is forecast to yield 440,000 acre feet (54 percent of average); the Greybull River nr Meeteese should yield 85,000 acre feet (43 percent of average); Shell Creek near Shell should yield 37,000 acre feet (51 percent of average) and the Bighorn River at Kane should yield 560,000 acre feet (51 percent of average). 

==================================================================================================================================
                                                       BIGHORN RIVER BASIN
                                               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)
====================================================================|=======================|=====================================
BOYSEN RESERVOIR Inflow (2)          APR-SEP        88       298    |      440        54    |       582       792            809
                                                                    |                       |
GREYBULL RIVER nr Meeteetse          APR-SEP        53        72    |       85        43    |        98       117            200
                                                                    |                       |
SHELL CREEK nr Shell                 APR-SEP        26        33    |       37        51    |        41        48             72
                                                                    |                       |
BIGHORN RIVER at Kane (2)            APR-SEP        51       354    |      560        51    |       766      1069           1110
                                                                    |                       |
==================================================================================================================================
                           BIGHORN RIVER BASIN                          |                   BIGHORN RIVER BASIN
             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
========================================================================|=========================================================
BOYSEN                                 596.0     82.8    457.1    620.4 |   NOWOOD RIVER                2       101        69
                                                                        |
BIGHORN LAKE                          1356.0    753.1    881.0    911.1 |   GREYBULL RIVER              2       105        51
                                                                        |
                                                                        |   SHELL CREEK                 3       116        85
                                                                        |
                                                                        |   BIGHORN (Boysen-Bighorn)    7       111        74
                                                                        |
==================================================================================================================================
 * 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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