Bighorn River Basin
March 1997

Snow
All drainage's in the basin are above average at this time. The Greybull River drainage is very near last years SWE, with 149 percent of average. Shell Creek SWE is lower, at only 20 percent above average. The basin SWE, as a whole, is currently 126 percent of March 1 average. SWE for the entire basin is 18 percent ahead of March 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 127 percent of average. Only 1 site, Sunshine (47 percent), is below average. February precipitation was 126 percent of the monthly average. Timber Creek reported 233 percent of the February average.

Reservoir
Reservoir storage is good in the basin with Bighorn Lake at 94 percent of average and Boysen at 94 percent. Boysen is currently storing 524,000 acre feet and Bighorn Lake is at 762,400. This is just slightly less than what was being stored last year at this time.

Streamflow
All forecast points are predicted to be average to well above average. The Wind River below Boysen is forecast to yield 1,190,000 acre feet (147 percent of average); the Nowood River near Ten Sleep should yield near 78,000 acre feet (135 percent of normal); the Greybull River near Meeteese should yield 290,000 acre feet (144 percent of average); Shell Creek near Shell should yield 88,000 acre feet (117 percent of average) and the Bighorn River at Kane should yield 1,730,000 acre feet (154 percent of average). 

==================================================================================================================================
                                                       BIGHORN RIVER BASIN
                                               Streamflow Forecasts - March 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       868      1060    |     1190       147    |      1320      1512            809
                                                                    |                       |
NOWOOD RIVER near Tensleep           APR-SEP        47        66    |       78       135    |        90       109             58
                                                                    |                       |
GREYBULL RIVER at Meeteetse          APR-SEP       248       273    |      290       144    |       307       332            201
                                                                    |                       |
SHELL CREEK near Shell               APR-SEP        77        84    |       88       117    |        92        99             75
                                                                    |                       |
BIGHORN RIVER at Kane (2)            APR-SEP      1304      1542    |     1730       154    |      1918      2158           1124
                                                                    |                       |
==================================================================================================================================
                           BIGHORN RIVER BASIN                          |                   BIGHORN RIVER BASIN
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 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    524.0    553.9    555.2 |   NOWOOD RIVER                5       132       128
                                                                        |
BIGHORN LAKE                          1356.0    762.4    821.4    810.4 |   GREYBULL RIVER              2       103       149
                                                                        |
                                                                        |   SHELL CREEK                 4       114       120
                                                                        |
                                                                        |   BIGHORN (Boysen-Bighorn)   11       118       126
                                                                        |
==================================================================================================================================
 * 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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