Belle Fourche and Cheyenne River Basins
January 1997

Snow
Snowpack in the Black Hills is much above average for January 1. Snow water equivalent (SWE) is 179 percent of average and nearly equal to the maximum SWE received at the beginning of January. This is more than double what the figure was at this time last year. All reporting sites are measuring well above average, at this time.

Precipitation
Precipitation for December was 285 percent of average, nearly three times the average. Warren Peak reported in with 458 percent of average for the month. The lowest reporting station in December was Ditch Creek, at 164 percent of average. Year to date figures are also very high; the basin, as a whole, is at 193 percent of average. Ditch Creek also has the lowest year to date precipitation, at 153 percent of average. The highest reporting site, as of January 1, is Mallo with 222 percent of average for the year.

Reservoir
Reservoir storage is in good shape; two reservoirs are just slightly below average and 4 are above average. Angostura is currently storing 93 percent of average (89,400 acre feet), Belle Fourche 151 percent of average (136,600 acre feet), Deerfield is storing 125 percent of average (15,500 acre feet), Keyhole is storing 144 percent of average (141,800 acre feet), Pactola is storing 118 percent of average (54,200 acre feet), and Shadehill is storing 87 percent of average (44,100 acre feet).

Streamflow
Runoff could be well above average for the Black Hills if the current trend continues. Castle Creek is forecast at 153 percent of average flow (7,500 acre feet) for the March - July season. Rapid Creek is even higher at 167 percent of average (35,000 acre feet). Shortages of water should not be a problem this year in the basin. 

==================================================================================================================================
                                              BELLE FOURCHE & CHEYENNE RIVER BASINS
                                               Streamflow Forecasts - January 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)   MAR-JUL      5.34      6.63    |     7.50       153    |      8.37      9.66           4.90
                                                                    |                       |
RAPID CREEK blw Pactola Dam (2)      MAR-JUL        21        29    |       35       167    |        41        49             21
                                                                    |                       |
==================================================================================================================================
                  BELLE FOURCHE & CHEYENNE RIVER BASINS                 |          BELLE FOURCHE & CHEYENNE RIVER BASINS
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 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     89.4     90.3     96.4 |   BELLE FOURCHE               4       232       179
                                                                        |
BELLE FOURCHE                          178.4    136.6    151.7     90.6 |
                                                                        |
DEERFIELD                               15.2     15.4     14.6     12.3 |
                                                                        |
KEYHOLE                                193.8    141.8    108.0     98.2 |
                                                                        |
PACTOLA                                 55.0     54.2     55.3     45.8 |
                                                                        |
SHADEHILL                               81.4     44.1     43.2     50.7 |
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual flow 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 flow - actual flow may be affected by upstream water management.
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