Wind River Basin (3)
June 1999

Snow
The Wind River basin has above average snow water equivalent (SWE) for this time of the year. The Wind River above Dubois is 160 percent of average (194 percent of last year). The Little Wind is 231 percent of average water content (228 percent of last year), and the Popo Agie drainage is about 194 percent of average (414 percent of last year). The Wind River basin, above Boysen Reservoir, SWE is about 193 percent of average (about 291 percent of last year). See the Basin Summary of Snow Course Data at the front of this report for details.

Precipitation
May precipitation in the basin varied from 36 to 287 percent of average. May precipitation for the basin was about 103 percent of average for the 11 reporting stations; that is about 151 percent of last May's amount. Water year-to-date precipitation is 135 percent of normal. The current water- year-to-date average is about 140 percent of last year at this time. Year to date figures range from 104 to 170 percent of average for the 11 reporting stations.

Reservoirs
Current storage varies from 65 to 102 percent of average. Bull Lake is currently storing about 94,400 acre feet (62 percent of capacity) -- normally the reservoir is at 61 percent of capacity at this time of the year. Boysen Reservoir is storing about 82 percent of capacity (490,400 acre feet) -- normally the reservoir is at 92 percent of capacity at this time of the year. Pilot Butte is storing 53 percent of capacity (16,600 acre feet) -- normally the reservoir is at 81 percent of capacity at this time of the year.

Streamflow
Water supply is estimated to be above normal this year. The following values reflect the 50 percent chance yields for the June through September runoff period. In the upper portion of the drainage, Wind River near Dubois is expected to yield about 92,000 acre feet (about 124 percent of average). The Wind River above Bull Lake Creek is expected to yield 530,000 acre feet (126 percent of average). Wind River at Riverton will yield about 680,000 acre feet (135 percent of average). Boysen Reservoir inflow will yield about 825,000 acre feet (143 percent of normal). Bull Lake Creek near Lenore is expected to yield about 195,000 acre feet (127 percent of average). Little Popo Agie River near Lander is expected to yield about 45,000 acre feet (122 percent of average). South Fork of Little Wind near Fort Washakie will yield about 82,000 acre feet (130 percent of average). Little Wind River near Riverton will yield about 295,000 acre feet (122 percent of average).

==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - June 1, 1999
==================================================================================================================================
                                              |  <<====== 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 (D)           JUN-SEP        84        89    |       92       124    |        95       100             74
                                                                    |                       |
WIND RIVER abv Bull Lake Cr (2)      JUN-SEP       494       515    |      530       126    |       545       566            420
                                                                    |                       |
WIND RIVER at Riverton (2)           JUN-SEP       560       631    |      680       135    |       729       800            505
                                                                    |                       |
BOYSEN Reservoir Inflow (2)          JUN-SEP       618       741    |      825       136    |       909      1032            609
                                                                    |                       |
BULL LAKE CR near Lenore (2)         JUN-SEP       180       189    |      195       127    |       201       210            154
                                                                    |                       |
LT POPO AGIE RIVER nr Lander         JUN-SEP        40        43    |       45       122    |        47        50             37
                                                                    |                       |
SF LT WIND nr Fort Washakie          JUN-SEP        75        79    |       82       130    |        85        89             63
                                                                    |                       |
LT WIND RIVER nr Riverton            JUN-SEP       257       280    |      295       122    |       310       333            241
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of May                   |        Watershed Snowpack Analysis - June 1, 1999
==================================================================================================================================
                                      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     94.4    116.2     92.7 |   WIND RIVER above Dubios     3       194       160
                                                                        |
BOYSEN                                 596.0    490.4    447.6    546.4 |   LITTLE WIND                 2       228       231
                                                                        |
PILOT BUTTE                             31.6     16.6     18.1     25.5 |   POPO AGIE                   3       414       194
                                                                        |
                                                                        |   WIND above Boysen Resv      7       291       193
                                                                        |
==================================================================================================================================
 * 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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