Wind River Basin (3)
March 1998

Snow
The Wind River basin has above average snow water equivalent (SWE) for this time of the year; measured snow depths ranged from 26 to 49 inches. SWE, in the Wind River basin above Boysen Reservoir is about 5 percent above average (About 28 percent less than last year). Above Dubois, the water content is just average for this time of the year. The Little Wind is also at average water content and the Popo Agie drainage is about 5 percent below normal. SWE, for nearly all reporting stations, is lower than last year at this time. See the Basin Summary Of Snow Course Data at the front of this report for details.

Precipitation
February precipitation in the basin varied from 26 percent of average, at Burroughs Creek SNOTEL, to 167 percent of average for Riverton. February's average precipitation for the basin was about 43 percent below normal for the 14 reporting stations; that is about 13 percent below last year's amount. Water year-to-date precipitation is 8 percent below normal. The current water-year-to-date average is about 66 percent of last year at this time.

Reservoirs
Current storage varies from 63 to 89 percent of average. Current storage, compared to average for the three storage reservoirs in the basin, is as follows; Bull Lake 112% (95,200 acre feet), Boysen 96% (531,200 acre feet), and Pilot Butte 123% (21,700 acre feet). Bull Lake is about 17 percent above last year's storage amount, while Boysen is 1 percent more and Pilot Butte is 7 percent less than last year at this time.

Streamflow
Water supply is estimated to be below normal this year. The following values reflect the 50 percent chance yields. In the upper portion of the drainage, Wind River near Dubois is expected to yield about 96,000 acre feet (about 6 percent below normal) during the April to September period. Other forecast points on the Wind River drainage include Wind River above Bull Lake 515,000 acre feet (4% below normal), Wind River at Riverton 615,000 acre feet (5% below average), and below Boysen 760,000 acre feet (6 % below normal). Bull Lake Creek near Lenore is expected to yield about 175,000 acre feet (4% below normal), Little Popo Agie River near Lander about 50,000 acre feet (4% below normal), South Fork of Little Wind near Fort Washakie about 72,000 acre feet (11% below normal), and Little Wind River near Riverton about 275,000 acre feet (15 percent less than normal). 

==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - March 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               APR-SEP        72        86    |       96        94    |       106       120            102
                                                                    |                       |
WIND RIVER abv Bull Lake Cr (2)      APR-SEP       404       470    |      515        96    |       560       626            538
                                                                    |                       |
WIND RIVER at Riverton (2)           APR-SEP       445       546    |      615        95    |       684       785            648
                                                                    |                       |
WIND RIVER below Boysen (2)          APR-SEP       438       630    |      760        94    |       890      1082            809
                                                                    |                       |
BULL LAKE CREEK near Lenore (2)      APR-SEP       135       159    |      175        96    |       191       215            183
                                                                    |                       |
LITTLE POPO AGIE RIVER near Lander   APR-SEP        32        43    |       50        96    |        57        68             52
                                                                    |                       |
SF LITTLE WIND RIVER nr Fort Washaki APR-SEP        55        65    |       72        89    |        79        89             81
                                                                    |                       |
LITTLE WIND RIVER near Riverton      APR-SEP       138       220    |      275        85    |       330       412            324
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 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     95.2     81.1     85.0 |   WIND RIVER above Dubios     7        63       100
                                                                        |
BOYSEN                                 596.0    531.2    524.0    555.2 |   LITTLE WIND                 2        79       100
                                                                        |
PILOT BUTTE                             31.6     21.7     23.5     17.7 |   POPO AGIE                   6        70        95
                                                                        |
                                                                        |   WIND above Boysen Resv     14        67        99
                                                                        |
==================================================================================================================================
 * 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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