Powder and Tongue River Basins (6)
June 2001

Snow
All the SNOTEL sites in this basin have melted out For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
May precipitation was 51 percent of average for the 10 reporting stations (46 percent of last year). Monthly percentages range from 7 to 93 percent of average. Precipitation for the year ranges from 52 to 78 percent of average at the reporting stations. Year-to-date precipitation is about 69 percent of average in the basin; this is 69 percent of last year at this time.

Reservoir
Tongue River Reservoir is currently at 94 percent of average usable storage for this time of year (45,200 acre feet) – the reservoir is about 57 percent of capacity (total capacity is 79,100 acre feet). Last year at this time the reservoir was storing about 79,400 acre feet – average storage is about 48,200 acre feet for this time of the year. Detailed reservoir data is shown on the following page and on the reservoir storage summary at the beginning of this report.

Streamflow Yield from this basin will be much below normal. Irrigators relying on direct diversion from streams may experience some water shortages. The following runoff values are for the 50 percent probability during the June through September forecast period. The estimated yield for Tongue River near Dayton is 25,000-acre feet (33 percent of normal). Middle Fork of the Powder River near Barnum is estimated to yield 2,000 acre feet (25 percent of average). The North Fork of the Powder near Hazelton should yield about 1,200 acre-feet (20 percent of normal). The estimated yield for Clear Creek near Buffalo is 11,000 acre-feet (39 percent of average). Rock Creek near Buffalo will yield about 4,500 acre-feet (27 percent of normal), and Piney Creek at Kearny should yield about 3,000 acre-feet (9 percent of average). ================================================================================================================================== POWDER & TONGUE RIVER BASINS Streamflow Forecasts - June 1, 2001 ================================================================================================================================== | <<====== 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) ====================================================================|=======================|===================================== TONGUE RIVER nr Dayton (2) JUN-SEP 19.8 23 | 25 33 | 31 41 77 | | MIDDLE FORK POWDER nr Barnum JUN-SEP 1.18 1.67 | 2.00 25 | 3.32 5.26 7.90 | | NORTH FORK POWDER nr Hazelton JUN-SEP 0.90 1.08 | 1.20 20 | 1.80 2.69 6.00 | | CLEAR CREEK nr Buffalo JUN-SEP 6.8 9.3 | 11.0 39 | 15.4 22 28 | | ROCK CREEK nr Buffalo JUN-SEP 3.4 4.1 | 4.5 27 | 6.1 8.4 16.8 | | PINEY CREEK at Kearny JUN-SEP 2.2 2.7 | 3.0 9 | 6.5 11.7 32 | | ================================================================================================================================== POWDER & TONGUE RIVER BASINS | POWDER & TONGUE RIVER BASINS Reservoir Storage (1000 AF) - End of May | Watershed Snowpack Analysis - June 1, 2001 ================================================================================================================================== Usable | *** Usable Storage *** | Number This Year as % of Reservoir Capacity| This Last | Watershed of ================= | Year Year Avg | Data Sites Last Yr Average ========================================================================|========================================================= TONGUE RIVER 79.1 45.2 79.4 48.2 | UPPER TONGUE RIVER 6 0 0 | | GOOSE CREEK 2 0 0 | | CLEAR CREEK 2 0 0 | | CRAZY WOMAN CREEK 1 0 0 | | UPPER POWDER RIVER 3 0 0 | | POWDER RIVER in WY 5 0 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. (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.

To June 2001 Basin Outlook Report Contents Page