June 2000 Water Supply Outlook - Wind River Basin (3)

Wind River Basin (3)
June 2000

Snow
The Wind River basin has well below average snow water equivalent (SWE) for this time of the year. SWE in the Wind River above Dubois is 41 percent of average (20 percent of last year). The Little Wind SWE is 2 percent of average water content (1 percent of last year), and the Popo Agie drainage SWE is about 1 percent of average (1 percent of last year). The Wind River basin, above Boysen Reservoir, SWE is about 23 percent of average (about 11 percent of last year). Snow has mostly melted from the Wind River Basin collection sites. See the Basin Summary of Snow Course Data at the front of this report for details.

Precipitation
May precipitation in the basin varied from 60 to 190 percent of average. May precipitation for the basin was about 106 percent of average for the 8 reporting stations; that is about 106 percent of last year's amount. Water year-to-date precipitation is 82 percent of normal. The current water- year-to-date average is about 63 percent of last year at this time. Year to date figures range from 58 to 92 percent of average.

Reservoirs
Current storage varies from 96 to 102 percent of average. Bull Lake is currently storing about 112,900 acre feet (74 percent of capacity) -- normally the reservoir is at 61 percent of capacity at this time of the year. Boysen Reservoir is storing about 91 percent of capacity 542,900 acre feet) -- normally the reservoir is at 92 percent of capacity at this time of the year. Pilot Butte is storing 78 percent of capacity (24,500 acre feet) -- normally the reservoir is at 81 percent of capacity at this time of the year.

Streamflow
Water supply is estimated to be below normal this year. The following values reflect the 50 percent chance yields for the June through September runoff period. The Wind River above Bull Lake Creek is expected to yield 360,000 acre feet (86 percent of average). Wind River at Riverton will yield about 370,000 acre feet (73 percent of average). Boysen Reservoir inflow will yield about 355,000 acre feet (58 percent of normal). Bull Lake Creek near Lenore is expected to yield about 115,000 acre feet (75 percent of average). Little Popo Agie River near Lander is expected to yield about 12,500 acre feet (34 percent of average). South Fork of Little Wind near Fort Washakie will yield about 37,000 acre feet (59 percent of average). Little Wind River near Riverton will yield about 110,000 acre feet (46 percent of average).

==================================================================================================================================
                                                         WIND RIVER BASIN
                                               Streamflow Forecasts - June 1, 2000
==================================================================================================================================
                                              |  <<====== 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)      JUN-SEP       324       345    |      360        86    |       375       396            420
                                                                    |                       |
WIND RIVER at Riverton (2)           JUN-SEP       250       321    |      370        73    |       419       490            505
                                                                    |                       |
BOYSEN RESERVOIR Inflow (2)          JUN-SEP       148       271    |      355        58    |       439       562            609
                                                                    |                       |
BULL LAKE CR near Lenore (2)         JUN-SEP       100       109    |      115        75    |       121       130            154
                                                                    |                       |
LT POPO AGIE RIVER nr Lander         JUN-SEP       7.8      10.6    |     12.5        34    |      14.4      17.2             37
                                                                    |                       |
SF LT WIND nr Fort Washakie          JUN-SEP        30        34    |       37        59    |        40        44             63
                                                                    |                       |
LT WIND RIVER nr Riverton            JUN-SEP        72        95    |      110        46    |       125       148            241
                                                                    |                       |
==================================================================================================================================
                            WIND RIVER BASIN                            |                    WIND RIVER BASIN
             Reservoir Storage (1000 AF) - End of May                   |        Watershed Snowpack Analysis - June 1, 2000
==================================================================================================================================
                                      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    112.9     94.4     92.7 |   WIND RIVER above Dubios     3        20        41
                                                                        |
BOYSEN                                 596.0    542.9    490.4    546.4 |   LITTLE WIND                 2         1         2
                                                                        |
PILOT BUTTE                             31.6     24.5     16.6     25.5 |   POPO AGIE                   3         1         1
                                                                        |
                                                                        |   WIND above Boysen Resv      7        11        23
                                                                        |
==================================================================================================================================
 * 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.


	BIGHORN RIVER BASIN as of June 1, 2000

To June 2000 Basin Outlook Report Contents Page

Wind River Basin (3) June 2000

Wind River Basin (3)
June 2000