Wind River Basin (3)
January 1999

Snow
The Wind River basin has near average to slightly above average snow water equivalent (SWE) for this time of the year. The Wind River above Dubois is 116 percent of average (144 percent of last year). The Little Wind is 109 percent of average water content (103 percent of last year), and the Popo Agie drainage is about 95 percent of average (112 percent of last year). The Wind River basin, above Boysen Reservoir, SWE is about 115 percent of average (About 125 percent of last year). See the Basin Summary of Snow Course Data at the front of this report for details.

Precipitation
December precipitation in the basin varied from 0 to 105 percent of average. December precipitation for the basin was about 77 percent of average for the 14 reporting stations; that is about 78 percent of last December's amount. Water year-to-date precipitation is 116 percent of normal. The current water-year-to-date average is about 131 percent of last year at this time. Year to date figures range from 71 to 303 percent.

Reservoirs
Current storage varies from 97 to 146 percent of average. Bull Lake is currently storing about 98,100 acre feet (110 percent of average). Boysen Reservoir is storing about 593,100 acre feet (97 percent of average). Pilot Butte is storing 22,700 acre feet (146 percent of average). Bull Lake is about 101 percent of last year's storage amount, while Boysen is 104 percent of last year, and Pilot Butte is 102 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 April through September runoff period. In the upper portion of the drainage, Wind River near Dubois is expected to yield about 113,000 acre feet (about 111 percent of average). The Wind River above Bull Lake Creek is expected to yield 542,000 acre feet (101 percent of average). Wind River at Riverton will yield about 649,000 acre feet (100 percent of average). Wind River at Boysen will yield about 805,000 acre feet (100 percent of normal). Bull Lake Creek near Lenore is expected to yield about 182,000 acre feet (100 percent of average). Little Popo Agie River near Lander is expected to yield about 50,000 acre feet (97 percent of average). South Fork of Little Wind near Fort Washakie will yield about 92,000 acre feet (114 percent of average). Little Wind River near Riverton will yield about 319,000 acre feet (99 percent of average). 

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                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - June 1, 1998
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                                              |  <<====== 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
                                                                    |                       |
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                            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
                                                                        |
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 * 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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