Belle Fourche and Cheyenne River Basins (7)
March 1998

Snow.
As of March 1, snow water equivalent (SWE) in the Black Hills is 92 percent of average. SWE at Warren Peak is 24 percent above average. Basin SWE is 60 percent of last year's amount. Measured snow depths ranged from 3 inches at Bearlodge Divide to 22 inches at Reuter Canyon. All the reporting sites are below last years figures at this time.

Precipitation.
Precipitation, for the month of February was 332 percent of average in the Black Hills. Of the 2 reporting sites in the basin, Warren Peak had the highest percentage of average for February (510 percent of average). Blind Park received 213 percent of average for the month. Year-to-date precipitation is 163 percent of average and 76 percent of last years amount.

Reservoir.
Reservoir storage is in good shape. Angostura is currently storing 117 percent of average (119,400 acre feet), Belle Fourche is storing 156 percent of average (113,000 acre feet), Deerfield is storing 115 percent of average (13,200 acre feet), Keyhole is storing 173 percent of average (101,900 acre feet), Pactola is storing 117 percent of average (46,000 acre feet), and Shadehill is storing 112 percent of average (50,000 acre feet).

Streamflow
Water users should see below average runoff for the Black Hills during the March- July period. Castle Creek is estimated to yield 61 percent of average (3,000 acre feet). Yields in the Rapid Creek drainage should be 11,500 acre feet (55 percent of average) for the March - July period. There could be irrigation water shortages in the basin this year. 

==================================================================================================================================
                                              BELLE FOURCHE & CHEYENNE RIVER BASINS
                                               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)
====================================================================|=======================|=====================================
CASTLE CREEK blw Deerfield Dam (2)   MAR-JUL      1.65      2.45    |     3.00        61    |      3.55      4.35           4.90
                                                                    |                       |
RAPID CREEK blw Pactola Dam (2)      MAR-JUL       2.3       7.8    |     11.5        55    |      15.2        21             21
                                                                    |                       |
==================================================================================================================================
                  BELLE FOURCHE & CHEYENNE RIVER BASINS                 |          BELLE FOURCHE & CHEYENNE RIVER BASINS
             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
========================================================================|=========================================================
ANGOSTURA                              122.1    119.4    121.1    101.7 |   BELLE FOURCHE               5        62        98
                                                                        |
BELLE FOURCHE                          178.4    176.6    170.6    113.0 |
                                                                        |
DEERFIELD                               15.2     15.2     14.6     13.2 |
                                                                        |
KEYHOLE                                193.8    175.8    162.9    101.9 |
                                                                        |
PACTOLA                                 55.0     53.7     53.0     46.0 |
                                                                        |
SHADEHILL                               81.4     56.2     41.9     50.0 |
                                                                        |
==================================================================================================================================
 * 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.
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