Wind River Basin (3)
June 1998

Snow
The Wind River basin has below average snow water equivalent (SWE) for this time of the year. The Wind River above Dubois is 83 percent of average (79 percent of last year). The Little Wind is 101 percent of average water content (75 percent of last year), and the Popo Agie drainage is about 47 percent of average (48 percent of last year). The Wind River basin, above Boysen Reservoir, SWE is about 83 percent of average (About 79 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 percent of average, at Lander WSO AP, to 100 percent of average for Saint Lawrence Ranger Station SNOTEL. May's average precipitation for the basin was about 69 percent of average for the 13 reporting stations; that is about 80 percent of last year's amount. Water year-to-date precipitation is 96 percent of normal. The current water-year-to-date average is about 79 percent of last year at this time.

Reservoir
Current storage varies from 71 to 125 percent of average. Bull Lake is currently storing about 116,200 acre feet (125 percent of average). Boysen Reservoir is storing about 447,600 acre feet (82 percent of average). Pilot Butte is storing 18,100 acre feet (71 percent of average). Bull Lake is about 119 percent of last year's storage amount, while Boysen is 106 percent of last year, and Pilot Butte is 82 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 June through September runoff period. In the upper portion of the drainage, Wind River near Dubois is expected to yield about 63,000 acre feet (about 85 percent of average). The Wind River above Bull Lake Creek is expected to yield 380,000 acre feet (91 percent of average). Wind River at Riverton will yield about 430,000 acre feet (85 percent of average). Wind River below Boysen will yield about 500,000 acre feet (82 percent of normal). Bull Lake Creek near Lenore is expected to yield about 135,000 acre feet (88 percent of average). Little Popo Agie River near Lander is expected to yield about 29,000 acre feet (78 percent of average). South Fork of Little Wind near Fort Washakie will yield about 55,000 acre feet (87 percent of average). Little Wind River near Riverton will yield about 195,000 acre feet (81 percent of average). 

==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - June 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               JUN-SEP        50        58    |       63        85    |        68        76             74
                                                                    |                       |
WIND RIVER abv Bull Lake Cr (2)      JUN-SEP       303       349    |      380        91    |       411       457            420
                                                                    |                       |
WIND RIVER at Riverton (2)           JUN-SEP       298       376    |      430        85    |       484       562            505
                                                                    |                       |
WIND RIVER below Boysen (2)          JUN-SEP       293       416    |      500        82    |       584       707            609
                                                                    |                       |
BULL LAKE CREEK near Lenore (2)      JUN-SEP       107       124    |      135        88    |       146       163            154
                                                                    |                       |
LITTLE POPO AGIE RIVER near Lander   JUN-SEP      17.8        25    |       29        78    |        34        40             37
                                                                    |                       |
SF LITTLE WIND RIVER near Fort Washa JUN-SEP        44        51    |       55        87    |        60        66             63
                                                                    |                       |
LITTLE WIND RIVER near Riverton      JUN-SEP       153       178    |      195        81    |       212       237            241
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of May                   |        Watershed Snowpack Analysis - June 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    116.2     97.5     92.7 |   WIND RIVER above Dubios     3        79        83
                                                                        |
BOYSEN                                 596.0    447.6    420.9    546.4 |   LITTLE WIND                 2        75       101
                                                                        |
PILOT BUTTE                             31.6     18.1     22.2     25.5 |   POPO AGIE                   3        48        47
                                                                        |
                                                                        |   WIND above Boysen Resv      7        65        66
                                                                        |
==================================================================================================================================
 * 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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