Wind River Basin (3)
January 1998

Snow
The Wind River basin has below average snow water equivalent (SWE) for this time of the year. SWE, in the Wind River basin above Boysen Reservoir is about 16 percent below normal (About 53 percent less than last year). Above Dubois, the water content is about 20 percent below normal for this time of the year, while the Little Wind is about 5 percent above normal and the Popo Agie drainage is about 15 percent below normal. SWE, for nearly all reporting stations, is lower than last year at this time. See the Basin Summary Of Snow Course Data at the front of this report for details.

Precipitation
December precipitation in the basin, varied from 73 percent of average at Burroughs Creek to 433 percent of average for Pavillion. December's average precipitation for the basin was nearly normal (2 percent above average for the 15 reporting stations); that is about 38 percent of last year's amount. Water year-to-date precipitation is 89 percent of normal. The current water-year-to-date average is about 57 percent of last year at this time.

Reservoirs
Current storage varies from 77 to 105 percent of average. Current storage, compared to average for the three storage reservoirs in the basin, is as follows; Bull Lake 109% (97,200 acre feet), Boysen 93% (569,100 acre feet), and Pilot Butte 144% (22,300 acre feet). Bull Lake is about 23 percent above last year's storage amount, while Boysen is 2 percent more and Pilot Butte is 6 percent more than last year at this time.

Streamflow
Water supply is estimated to be below normal this year. In the upper portion of the drainage, Wind River near Dubois is expected to yield about 82,000 acre feet (about 20 percent below normal) during the April to September period. Other forecast points on the Wind River drainage include Wind River above Bull Lake 440,000 acre feet (20% below normal), Wind River at Riverton 500,000 acre feet (23% below average), and below Boysen 655,000 acre feet (19 % below normal). Bull Lake Creek near Lenore is expected to yield about 160,000 acre feet (13% below normal), Little Popo Agie River near Lander about 42,000 acre feet (19% below normal), South Fork of Little Wind near Fort Washakie about 68,000 acre feet (16% below normal), and Little Wind River near Riverton about 260,000 acre feet (20 percent less than normal). 

==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - January 1, 1998
==================================================================================================================================
                                              |  <<====== 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 near Dubois               APR-SEP        54        71    |       82        80    |        93       110            102
                                                                    |                       |
WIND RIVER abv Bull Lake Cr (2)      APR-SEP       260       367    |      440        82    |       513       620            538
                                                                    |                       |
WIND RIVER at Riverton (2)           APR-SEP       249       398    |      500        77    |       602       751            648
                                                                    |                       |
WIND RIVER below Boysen (2)          APR-SEP       303       513    |      655        81    |       797      1007            809
                                                                    |                       |
BULL LAKE CREEK near Lenore (2)      APR-SEP       101       136    |      160        87    |       184       219            183
                                                                    |                       |
LITTLE POPO AGIE RIVER near Lander   APR-SEP      19.8        33    |       42        81    |        51        64             52
                                                                    |                       |
SF LITTLE WIND RIVER nr Fort Washaki APR-SEP        43        58    |       68        84    |        78        93             81
                                                                    |                       |
LITTLE WIND RIVER near Riverton      APR-SEP       135       210    |      260        80    |       310       385            324
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 1998
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
BULL LAKE                              151.8     97.2     78.8     88.8 |   WIND RIVER above Dubios     3        40        80
                                                                        |
BOYSEN                                 596.0    569.1    556.7    613.5 |   LITTLE WIND                 2        74       105
                                                                        |
PILOT BUTTE                             31.6     22.3     23.7     15.5 |   POPO AGIE                   3        51        85
                                                                        |
                                                                        |   WIND above Boysen Resv      7        47        85
                                                                        |
==================================================================================================================================
 * 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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