MILLS, Wyo. – Reclamation’s May Forecast of the May through July water runoff predicted for the Bighorn River Basin is as follows:
- Bighorn Lake - Bighorn River May through July inflow to Bighorn Lake is forecast to be approximately 623,000 acre-feet (af), which is 57% of the 30-year average of 1,095,400 af. As of May 1, Bighorn Lake is 81% full.
- Buffalo Bill Reservoir - Shoshone River May through July inflow to Buffalo Bill Reservoir is forecast at 650,000 af, which is 91% of the 30-year average of 714,000 af. As of May 1, Buffalo Bill is 59% full. *
- Boysen Reservoir - Wind River May through July inflow to Boysen Reservoir is forecast at 450,000 af, which is 78% of the 30-year average of 581,000 af. As of May 1, Boysen Reservoir is 69% full. *
- Bull Lake Reservoir - May through July snowmelt runoff into Bull Lake Reservoir from Bull Lake Creek is expected to be 135,000 af, which is 94% of the 30-year average of 143,000 af. As of May 1, Bull Lake Reservoir is 27% full. *
*Reservoir is considered "full" when the pool elevation is at top of active conservation or joint-use pool. The percentage is based on total reservoir volume below that level.
The Bighorn Basin is a plateau region and intermontane basin, approximately 100 miles (160 km) wide, in north-central Wyoming. It is bounded by the Absaroka Range on the west, the Pryor Mountains on the north, the Bighorn Mountains on the east, and the Wind River and Granite Mountains on the south. It is drained to the north by tributaries of the Bighorn River, which enters the basin from the southwest, and passes through a gap between the Owl Creek and Bridger Mountains as the Wind River before changing its name to the Bighorn River at Wedding of the Waters, south of Thermopolis.
Reclamation’s storage reservoirs in the basin have a combined storage capacity of 2.6 million acre-feet and most of that capacity is attributed to Bull Lake, Boysen and Buffalo Bill Reservoirs in Wyoming and Bighorn Lake in Montana. Hydropower is produced at Boysen Powerplant and four powerplants supplied by Buffalo Bill Reservoir in Wyoming and at Yellowtail Powerplant in Montana.
For additional information on Buffalo Bill, Boysen, and Bull Lake Reservoirs, contact Wyoming Area Manager Lyle Myler at 307-261-5671. For additional information on Bighorn Lake (Yellowtail), contact Montana Area Manager Ryan Newman at 406-247-7298.
