Bighorn River Basin (4)
June 1997

Snow
Most drainage's in the basin are getting close to melting out. The Nowood drainage is 28 percent of last year and 111 percent of average SWE for June 1. The Greybull River drainage is nearly melted out. Shell Creek SWE only 98 percent of average. The basin SWE, as a whole, is currently 89 percent of average for June 1. SWE for the entire basin is 46 percent of the June 1996 figure. 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 107 percent of average. May precipitation was 77 percent of the monthly average. Boysen Dam was the highest reporting station at 158 percent of the May average. Kirwin is currently the highest reporting station for the year with 135 percent of average.

Reservoir
Reservoir storage has been lowered in anticipation of the potentially high runoff. Bighorn Lake did not report this month. Boysen Reservoir is currently storing 420,900 acre feet (77 percent of average).

Streamflow
The remaining of the runoff season (Jun - Sep) should yield from well below average runoff on the Nowood to well above on the Wind River. The Wind River below Boysen is forecast to yield 750,000 acre feet (123 percent of average); the Nowood River near Ten Sleep should yield near 14,000 acre feet (67 percent of normal); the Greybull River near Meeteese should yield 150,000 acre feet (90 percent of average); Shell Creek near Shell should yield 48,000 acre feet (87 percent of average) and the Bighorn River at Kane should yield 750,000 acre feet (93 percent of average). 

==================================================================================================================================
                                                       BIGHORN RIVER BASIN
                                               Streamflow Forecasts - June 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)          JUN-SEP       543       666    |      750       123    |       834       957            609
                                                                    |                       |
NOWOOD RIVER near Tensleep           JUN-SEP      10.0      12.4    |     14.0        67    |      15.6      18.0             21
                                                                    |                       |
GREYBULL RIVER at Meeteetse          JUN-SEP       141       146    |      150        90    |       154       159            167
                                                                    |                       |
SHELL CREEK near Shell               JUN-SEP        39        44    |       48        87    |        52        57             55
                                                                    |                       |
BIGHORN RIVER at Kane (2)            JUN-SEP       376       599    |      750        93    |       901      1124            811
                                                                    |                       |
==================================================================================================================================
                           BIGHORN RIVER BASIN                          |                   BIGHORN RIVER BASIN
             Reservoir Storage (1000 AF) - End of May                   |        Watershed Snowpack Analysis - June 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    420.9    454.2    546.4 |   NOWOOD RIVER                2        28       111
                                                                        |
BIGHORN LAKE                          1356.0    846.3    824.1    855.6 |   GREYBULL RIVER              2         2         6
                                                                        |
                                                                        |   SHELL CREEK                 3        64        98
                                                                        |
                                                                        |   BIGHORN (Boysen-Bighorn)    7        46        89
                                                                        |
==================================================================================================================================
 * 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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