Belle Fourche and Cheyenne River Basins (7)
June 1997

Snow.
Snowpack in the Black Hills has melted out as of June 1.

Precipitation.
According to the 2 reporting sites, precipitation for May was 112 percent of average. Year to date figures are very high; the basin, as a whole, is 157 percent of average. The Belle Fourche basin , as of June 1, is 115 percent of last years precipitation amount.

Reservoir.
Reservoir storage is in good shape. Angostura is currently storing 106 percent of average (121,000 acre feet), Belle Fourche is 123 percent of average (186,900 acre feet), Deerfield is storing 111 percent of average (15,100 acre feet), Keyhole is storing 162 percent of average (184,600 acre feet), Pactola is storing 115 percent of average (55,700 acre feet), and Shadehill is storing 97 percent of average (66,700 acre feet).

Streamflow forecast.
Water users should see near average runoff for the Black Hills for the June - July period. Castle Creek is forecast at 100 percent of average flow (1,800 acre feet). Rapid Creek is at 102 percent of average (9,200 acre feet). Shortages of water should not be a problem this year in the basin. 

==================================================================================================================================
                                              BELLE FOURCHE & CHEYENNE RIVER BASINS
                                               Streamflow Forecasts - June 1, 1997
==================================================================================================================================
                                              |  <<====== 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)
====================================================================|=======================|=====================================
CASTLE CREEK blw Deerfield Dam (2)   JUN-JUL      1.22      1.57    |     1.80       100    |      2.03      2.38           1.80
                                                                    |                       |
RAPID CREEK blw Pactola Dam (2)      JUN-JUL      4.89      7.46    |     9.20       102    |     10.94     13.51           9.00
                                                                    |                       |
==================================================================================================================================
                  BELLE FOURCHE & CHEYENNE RIVER BASINS                 |          BELLE FOURCHE & CHEYENNE RIVER BASINS
             Reservoir Storage (1000 AF) - End of May                   |        Watershed Snowpack Analysis - June 1, 1997
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
ANGOSTURA                              122.1    121.0    121.8    117.2 |   BELLE FOURCHE               2         0         0
                                                                        |
BELLE FOURCHE                          178.4    186.9    196.1    152.3 |
                                                                        |
DEERFIELD                               15.2     15.1     15.4     13.6 |
                                                                        |
KEYHOLE                                193.8    184.0    153.4    113.6 |
                                                                        |
PACTOLA                                 55.0     55.7     58.4     48.6 |
                                                                        |
SHADEHILL                               81.4     66.7     72.5     68.7 |
                                                                        |
==================================================================================================================================
 * 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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