Precipitation
Reservoir
Streamflow
The 50 percent chance runoff is expected to be 48 to 59
percent above average for the June through September
runoff period. Yellowstone at Lake Outlet has a 50 percent
chance of yielding about 895,000 acre feet (30 percent
above normal). Yellowstone at Corwin Springs has a 50
percent chance of yielding about 2,050,000 acre feet (38
percent above normal). Yellowstone near Livingston has a
50 percent chance of yielding about 2,405,000 acre feet (40
percent above normal). Madison River near Grayling has a
50 percent chance of yielding about 440,000 acre feet (43
percent above normal). See the following page for detailed
runoff volumes.
================================================================================================================================== UPPER YELLOWSTONE & MADISON 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) ====================================================================|=======================|===================================== YELLOWSTONE at Lake Outlet JUN-SEP 803 858 | 895 130 | 932 987 691 | | YELLOWSTONE RIVER at Corwin Springs JUN-SEP 1889 1985 | 2050 138 | 2115 2211 1484 | | YELLOWSTONE RIVER near Livingston JUN-SEP 2206 2324 | 2405 140 | 2486 2604 1721 | | MADISON RIVER near Grayling (2) JUN-SEP 401 424 | 440 143 | 456 479 307 | | ================================================================================================================================== UPPER YELLOWSTONE & MADISON RIVER BASINS | UPPER YELLOWSTONE & MADISON 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 ========================================================================|========================================================= ENNIS LAKE 41.0 32.8 35.1 35.8 | MADISON RIVER in WY 6 75 176 | HEBGEN LAKE 377.5 330.5 312.0 309.8 | YELLOWSTONE RIVER in WY 7 77 142 | ================================================================================================================================== * 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.