Wind River Basin (3)
March 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 123 percent of average (126 percent of last year). The Little Wind is 119 percent of average water content (119 percent of last year), and the Popo Agie drainage is about 100 percent of average (106 percent of last year). The Wind River basin, above Boysen Reservoir, SWE is about 117 percent of average (About 113 percent of last year). See the Basin Summary of Snow Course Data at the front of this report for details.

Precipitation
February precipitation in the basin varied from 0 to 200 percent of average. February precipitation for the basin was about 155 percent of average for the 11 reporting stations; that is about 276 percent of last February's amount. Water year-to-date precipitation is 120 percent of normal. The current water-year-to-date average is about 132 percent of last year at this time. Year to date figures range from 105 to 153 percent.

Reservoirs
Current storage varies from 99 to 124 percent of average. Bull Lake is currently storing about 97,800 acre feet (115 percent of average). Boysen Reservoir is storing about 550,000 acre feet (99 percent of average). Pilot Butte is storing 22,000 acre feet (124 percent of average). Bull Lake is about 103 percent of last year's storage amount, while Boysen is 104 percent of last year, and Pilot Butte is 101 percent of last year at this time.

Streamflow
Water supply is estimated to be above 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 125,000 acre feet (about 119 percent of average). The Wind River above Bull Lake Creek is expected to yield 640,000 acre feet (119 percent of average). Wind River at Riverton will yield about 765,000 acre feet (118 percent of average). Boysen Reservoir inflow will yield about 970,000 acre feet (120 percent of normal). Bull Lake Creek near Lenore is expected to yield about 200,000 acre feet (109 percent of average). Little Popo Agie River near Lander is expected to yield about 60,000 acre feet (115 percent of average). South Fork of Little Wind near Fort Washakie will yield about 105,000 acre feet (130 percent of average). Little Wind River near Riverton will yield about 385,000 acre feet (119 percent of average).

==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - March 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       102       116    |      125       123    |       134       148            102
                                                                    |                       |
WIND RIVER abv Bull Lake Cr (2)      APR-SEP       534       597    |      640       119    |       683       746            538
                                                                    |                       |
WIND RIVER at Riverton (2)           APR-SEP       546       676    |      765       118    |       854       984            648
                                                                    |                       |
BOYSEN Reservoir Inflow (2)          APR-SEP       648       840    |      970       120    |      1100      1292            809
                                                                    |                       |
BULL LAKE CR near Lenore (2)         APR-SEP       160       184    |      200       109    |       216       240            183
                                                                    |                       |
LT POPO AGIE RIVER nr Lander         APR-SEP        41        52    |       60       115    |        68        79             52
                                                                    |                       |
SF LT WIND nr Fort Washakie          APR-SEP        77        94    |      105       130    |       116       133             81
                                                                    |                       |
LT WIND RIVER nr Riverton            APR-SEP       233       324    |      385       119    |       446       537            324
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 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     95.2     85.0 |   WIND RIVER above Dubios     7       126       123
                                                                        |
BOYSEN                                 596.0    550.0    531.2    555.2 |   LITTLE WIND                 2       119       119
                                                                        |
PILOT BUTTE                             31.6     22.0     21.7     17.7 |   POPO AGIE                   6       106       100
                                                                        |
                                                                        |   WIND above Boysen Resv     14       116       112
                                                                        |
==================================================================================================================================
 * 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.
(D) - The operational measurement of flow at this point has been discountinued. 

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