Bighorn River Basin (4)
February 2001

Snow
Snowpack in this basin is well below average for this time of year. The Nowood drainage SWE is 47 percent of average (59 percent of last year). Greybull River SWE is 46 percent of average (89 percent of last year). Shell Creek SWE is 60 percent of average (59 percent of last year). The basin SWE, as a whole, is currently 53 percent of average (61 percent of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
January precipitation was 36 percent of the monthly average (33 percent of last year). Sites ranged from 11 to 109 percent of average for the month. Year-to-date precipitation is 67 percent of normal; that is 78 percent of last year at this time. Year to date percentages, from the 10 reporting stations, range from 57 to 168.

Reservoir
Boysen Reservoir is currently storing 445,500-acre feet (77 percent of average). Bighorn Lake is now at 103 percent of average (865,000-acre feet). Boysen is currently storing 84 percent of last year at this time and Big Horn Lake is storing 92 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 500,000 acre feet (62 percent of average); the Greybull River nr Meeteese should yield 95,000 acre feet (47 percent of average); Shell Creek near Shell should yield 56,000 acre feet (75 percent of average) and the Bighorn River at Kane should yield 550,000 acre feet (49 percent of average). 

==================================================================================================================================
                                                       BIGHORN RIVER BASIN
                                               Streamflow Forecasts - February 1, 2001
==================================================================================================================================
                                              |  <<====== 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       299       421    |      500        62    |       630       822            809
                                                                    |                       |
GREYBULL RIVER nr Meeteetse          APR-SEP        78        88    |       95        47    |       109       129            201
                                                                    |                       |
SHELL CREEK nr Shell                 APR-SEP        45        51    |       56        75    |        61        67             75
                                                                    |                       |
BIGHORN RIVER at Kane (2)            APR-SEP       315       450    |      550        49    |       745      1034           1124
                                                                    |                       |
==================================================================================================================================
                           BIGHORN RIVER BASIN                          |                   BIGHORN RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 2001
==================================================================================================================================
                                      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    445.5    531.3    580.7 |   NOWOOD RIVER                5        59        47
                                                                        |
BIGHORN LAKE                          1356.0    865.0    941.9    839.2 |   GREYBULL RIVER              2        89        46
                                                                        |
                                                                        |   SHELL CREEK                 4        59        60
                                                                        |
                                                                        |   BIGHORN (Boysen-Bighorn)   11        61        53
                                                                        |
==================================================================================================================================
 * 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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