Streamflow forecast.
Runoff could be well above average for the Black Hills if the current trend
continues. Castle Creek is forecast at 143 percent of average flow (7,000
acre feet) for the March - July season. Rapid Creek is even higher at 143
percent of average (30,000 acre feet). Shortages of water should not be a
problem this year in the basin.
================================================================================================================================== BELLE FOURCHE & CHEYENNE RIVER BASINS Streamflow Forecasts - February 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 5.52 6.40 | 7.00 143 | 7.60 8.48 4.90 | | RAPID CREEK blw Pactola Dam (2) MAR-JUL 19.7 26 | 30 143 | 34 40 21 | | ================================================================================================================================== BELLE FOURCHE & CHEYENNE RIVER BASINS | BELLE FOURCHE & CHEYENNE RIVER BASINS Reservoir Storage (1000 AF) - End of January | Watershed Snowpack Analysis - February 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 94.0 92.3 98.1 | BELLE FOURCHE 7 183 190 | BELLE FOURCHE 178.4 155.8 163.5 101.4 | | DEERFIELD 15.2 15.0 14.7 12.8 | | KEYHOLE 193.8 148.1 108.5 98.7 | | PACTOLA 55.0 53.6 55.9 45.8 | | SHADEHILL 81.4 40.3 40.9 49.1 | | ================================================================================================================================== * 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.