Wind River Basin (3)
April 2001

Snow
The Wind River basin has much below average snow water equivalent (SWE) for this time of the year. SWE in the Wind River above Dubois is 57 percent of average (71 percent of last year). The Little Wind SWE is 42 percent of average water content (61 percent of last year), and the Popo Agie drainage SWE is about 45 percent of average (69 percent of last year). The Wind River basin, above Boysen Reservoir, SWE is about 50 percent of average (about 68 percent of last year). See the Basin Summary of Snow Course Data at the front of this report for details.

Precipitation
March precipitation in the basin varied from 16 to 86 percent of average. March precipitation for the basin was about 43 percent of average for the 10 reporting stations; that is about 47 percent of last year's amount. Water year-to-date precipitation is 51 percent of normal. The current water-year- to-date average is about 69 percent of last year at this time. Year to date figures range from 38 to 112 percent of average.

Reservoirs
Current usable storage varies from 75 to 108 percent of average. Bull Lake is currently storing about 62,200 acre feet (41 percent of capacity) -- the reservoir is at 75 percent of average at this time of the year. Boysen Reservoir is storing about 75 percent of capacity 447,200 acre feet) -- the reservoir is at 84 percent of average for this time of the year. Pilot Butte is storing 74 percent of capacity (23,300 acre feet) -- the reservoir is at 108 percent of average for this time of the year.

Streamflow
Water supply is estimated to be much below normal this year. The following values reflect the 50 percent chance yields for the April through September runoff period. The Wind River above Bull Lake Creek is expected to yield 320,000 acre feet (60 percent of average). Wind River at Riverton will yield about 300,000 acre feet (46 percent of average). Boysen Reservoir inflow will yield about 320,000 acre feet (40 percent of normal). Bull Lake Creek near Lenore is expected to yield about 105,000 acre feet (57 percent of average). Little Popo Agie River near Lander is expected to yield about 15,500 acre feet (30 percent of average). South Fork of Little Wind near Fort Washakie will yield about 40,000 acre feet (49 percent of average). Little Wind River near Riverton will yield about 160,000 acre feet (49 percent of average). 

==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - April 1, 2001
==================================================================================================================================
                                              |  <<====== 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 abv Bull Lake Cr (2)      APR-SEP       264       297    |      320        60    |       358       413            538
                                                                    |                       |
WIND RIVER at Riverton (2)           APR-SEP       206       262    |      300        46    |       383       504            648
                                                                    |                       |
BOYSEN RESERVOIR Inflow (2)          APR-SEP       201       272    |      320        40    |       440       616            809
                                                                    |                       |
BULL LAKE CR near Lenore (2)         APR-SEP        84        96    |      105        57    |       120       143            183
                                                                    |                       |
LT POPO AGIE RIVER nr Lander         APR-SEP      10.3      13.4    |     15.5        30    |        23        33             52
                                                                    |                       |
SF LT WIND nr Fort Washakie          APR-SEP        27        35    |       40        49    |        51        66             81
                                                                    |                       |
LT WIND RIVER nr Riverton            APR-SEP        87       131    |      160        49    |       220       308            324
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of March                 |        Watershed Snowpack Analysis - April 1, 2001
==================================================================================================================================
                                      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     62.2     95.4     83.4 |   WIND RIVER above Dubios     7        71        57
                                                                        |
BOYSEN                                 596.0    447.2    523.6    529.3 |   LITTLE WIND                 2        61        42
                                                                        |
PILOT BUTTE                             31.6     23.3     22.5     21.5 |   POPO AGIE                   6        69        45
                                                                        |
                                                                        |   WIND above Boysen Resv     14        68        50
                                                                        |
==================================================================================================================================
 * 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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