Wind River Basin (3)
February 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 117 percent of average (101 percent of last year). The Little Wind is 103 percent of average water content (95 percent of last year), and the Popo Agie drainage is about 88 percent of average (89 percent of last year). The Wind River basin, above Boysen Reservoir, SWE is about 108 percent of average (About 94 percent of last year). See the Basin Summary of Snow Course Data at the front of this report for details.

Precipitation
January precipitation in the basin varied from 0 to 143 percent of average. January precipitation for the basin was about 103 percent of average for the 11 reporting stations; that is about 79 percent of last January's amount. Water year-to-date precipitation is 113 percent of normal. The current water-year-to-date average is about 113 percent of last year at this time. Year to date figures range from 98 to 199 percent.

Reservoirs
Current storage varies from 98 to 135 percent of average. Bull Lake is currently storing about 97,800 acre feet (113 percent of average). Boysen Reservoir is storing about 569,300 acre feet (98 percent of average). Pilot Butte is storing 22,300 acre feet (135 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 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 April through September runoff period. In the upper portion of the drainage, Wind River near Dubois is expected to yield about 120,000 acre feet (about 118 percent of average). The Wind River above Bull Lake Creek is expected to yield 585,000 acre feet (109 percent of average). Wind River at Riverton will yield about 685,000 acre feet (106 percent of average). Boysen Reservoir inflow will yield about 860,000 acre feet (106 percent of normal). Bull Lake Creek near Lenore is expected to yield about 185,000 acre feet (101 percent of average). Little Popo Agie River near Lander is expected to yield about 51,000 acre feet (98 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 340,000 acre feet (105 percent of average). 

==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - February 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)           APR-SEP        93       109    |      120       118    |       131       147            102
                                                                    |                       |
WIND RIVER abv Bull Lake Cr (2)      APR-SEP       465       536    |      585       109    |       634       705            538
                                                                    |                       |
WIND RIVER at Riverton (2)           APR-SEP       449       590    |      685       106    |       780       921            648
                                                                    |                       |
BOYSEN Reservoir Inflow (2)          APR-SEP       538       730    |      860       106    |       990      1182            809
                                                                    |                       |
BULL LAKE CR near Lenore (2)         APR-SEP       144       168    |      185       101    |       202       226            183
                                                                    |                       |
LT POPO AGIE RIVER nr Lander         APR-SEP        21        39    |       51        98    |        63        81             52
                                                                    |                       |
SF LT WIND nr Fort Washakie          APR-SEP        63        80    |       92       114    |       104       121             81
                                                                    |                       |
LT WIND RIVER nr Riverton            APR-SEP       191       280    |      340       105    |       400       489            324
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 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     97.8     96.4     86.6 |   WIND RIVER above Dubios     7       101       117
                                                                        |
BOYSEN                                 596.0    569.3    549.3    580.7 |   LITTLE WIND                 2        95       103
                                                                        |
PILOT BUTTE                             31.6     22.3     21.7     16.5 |   POPO AGIE                   6        89        88
                                                                        |
                                                                        |   WIND above Boysen Resv     14        96       104
                                                                        |
==================================================================================================================================
 * 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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