Bighorn River Basin (4)
January 2000

Snow
Snowpack in this basin is below average for this time of year. The Nowood drainage is 82 percent of average SWE (110 percent of last year). The Greybull River drainage SWE is 38 percent of average (30 percent of last year). Shell Creek SWE is 93 percent of average (106 percent of last year). The basin SWE, as a whole, is currently 81 percent of average (88 percent of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
December precipitation was 118 percent of the monthly average (120 percent of last year). Sites ranged from 17 to 209 percent of average for the month. Year-to-date precipitation is 78 percent of normal; that is 62 percent of last year at this time. Year to date percentages, from the 14 reporting stations, range from 33 to 102.

Reservoir
Boysen Reservoir is currently storing 547,000-acre feet (89 percent of average). Bighorn Lake is now at 108 percent of average (960,300-acre feet). Boysen is currently storing 92 percent of last year at this time and Big Horn Lake is storing 102 percent of last year's volume.

Streamflow
The 50 percent chance April through September runoff is anticipated to be well below normal. The Wind River at Boysen is forecast to yield 525,000 acre feet (65 percent of average); the Nowood River near Ten Sleep should yield near 22,000 acre feet (38 percent of normal); the Greybull River at Meeteese should yield 100,000 acre feet (50 percent of average); Shell Creek near Shell should yield 65,000 acre feet (87 percent of average) and the Bighorn River at Kane should yield 726,000 acre feet (65 percent of average). 

==================================================================================================================================
                                                       BIGHORN RIVER BASIN
                                               Streamflow Forecasts - January 1, 2000
==================================================================================================================================
                                              |  <<====== 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       173       383    |      525        65    |       667       877            809
                                                                    |                       |
NOWOOD RIVER nr Tensleep (D)         APR-SEP       2.3       9.3    |       22        38    |        35        53             58
                                                                    |                       |
GREYBULL RIVER nr Meeteetse          APR-SEP        68        87    |      100        50    |       113       132            201
                                                                    |                       |
SHELL CREEK nr Shell                 APR-SEP        54        61    |       65        87    |        69        76             75
                                                                    |                       |
BIGHORN RIVER at Kane (2)            APR-SEP       281       520    |      726        65    |       932      1169           1124
                                                                    |                       |
==================================================================================================================================
                           BIGHORN RIVER BASIN                          |                   BIGHORN RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 2000
==================================================================================================================================
                                      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    547.0    593.1    613.5 |   NOWOOD RIVER                2       110        82
                                                                        |
BIGHORN LAKE                          1356.0    960.3    944.1    891.8 |   GREYBULL RIVER              2        30        38
                                                                        |
                                                                        |   SHELL CREEK                 3       106        93
                                                                        |
                                                                        |   BIGHORN (Boysen-Bighorn)    7        88        81
                                                                        |
==================================================================================================================================
 * 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.
(3) - Forecasts produced in cooperation with Alberta Forecasting Staff Canada
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