Wind River Basin (3)
May 1998

Snow
The Wind River basin has above average snow water equivalent (SWE) for this time of the year; measured snow depths ranged from 11 to 43 inches. Above Dubois, SWE is 110 percent average for this time of the year (66 percent of last year). The Little Wind is 124 percent of average water content (88 percent of last year), and the Popo Agie drainage is about 107 percent of average (77 percent of last year). The Wind River basin, above Boysen Reservoir, SWE is about 118 percent of average (About 77 percent of last year). See the Basin Summary Of Snow Course Data at the front of this report for details.

Precipitation
April precipitation in the basin varied from 56 percent of average, at Lander WSO AP, to 148 percent of average for Hobbs Park SNOTEL. April's average precipitation for the basin was about 105 percent of average for the 14 reporting stations; that is about 76 percent of last year's amount. Water year-to-date precipitation is 102 percent of normal. The current water-year-to-date average is about 78 percent of last year at this time.

Reservoir
Current storage varies from 82 to 120 percent of average. Bull Lake is currently storing about 95,700 acre feet (120 percent of average). Boysen Reservoir is storing about 450,800 acre feet (90 percent of average). Pilot Butte is storing 24,600 acre feet (82 percent of average). Bull Lake is about 119 percent of last year's storage amount, while Boysen is 118 percent of last year, and Pilot Butte is 103 percent of last year at this time.

Streamflow
Water supply is estimated to be near normal this year. The following values reflect the 50 percent chance yields for the May through September runoff period. In the upper portion of the drainage, Wind River near Dubois is expected to yield about 89,000 acre feet (about 94 percent of average). The Wind River above Bull Lake Creek is expected to yield 515,000 acre feet (101 percent of average). Wind River at Riverton will yield about 610,000 acre feet (100 percent of average). Wind River below Boysen will yield about 745,000 acre feet (98 percent of normal). Bull Lake Creek near Lenore is expected to yield about 180,000 acre feet (101 percent of average). Little Popo Agie River near Lander is expected to yield about 49,000 acre feet (100 percent of average). South Fork of Little Wind near Fort Washakie will yield about 72,000 acre feet (92 percent of average). Little Wind River near Riverton will yield about 290,000 acre feet (96 percent of average). 


==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - May 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               MAY-SEP        73        83    |       89        94    |        96       105             95
                                                                    |                       |
WIND RIVER abv Bull Lake Cr (2)      MAY-SEP       435       483    |      515       101    |       547       595            511
                                                                    |                       |
WIND RIVER at Riverton (2)           MAY-SEP       482       558    |      610       100    |       662       738            609
                                                                    |                       |
WIND RIVER below Boysen (2)          MAY-SEP       486       640    |      745        98    |       850      1004            758
                                                                    |                       |
BULL LAKE CREEK near Lenore (2)      MAY-SEP       149       168    |      180       101    |       192       211            179
                                                                    |                       |
LITTLE POPO AGIE RIVER near Lander   MAY-SEP        36        44    |       49       100    |        54        62             49
                                                                    |                       |
SF LITTLE WIND RIVER nr Fort Washaki MAY-SEP        57        66    |       72        92    |        78        87             78
                                                                    |                       |
LITTLE WIND RIVER near Riverton      MAY-SEP       191       250    |      290        96    |       330       389            303
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of April                 |        Watershed Snowpack Analysis - May 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     95.7     80.3     79.9 |   WIND RIVER above Dubios     7        66       110
                                                                        |
BOYSEN                                 596.0    450.8    381.3    502.6 |   LITTLE WIND                 2        88       124
                                                                        |
PILOT BUTTE                             31.6     24.6     23.8     30.1 |   POPO AGIE                   6        77       107
                                                                        |
                                                                        |   WIND above Boysen Resv     14        73       110
                                                                        |
==================================================================================================================================
 * 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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