The Bureau of Reclamation, at the request of the Wyoming Game and Fish Department and in coordination with Willwood Workgroup Two, has scheduled a flushing flow in the Shoshone River downstream of Buffalo Bill Dam.
The flushing flow will begin with rapidly increasing flows on April 11 and conclude on April 14. During this time, the flow will increase from 700 cubic feet per second (c.f.s) to 4,500 c.f.s. before maintaining at 1,200 c.f.s.
The increased flows from Buffalo Bill Dam following the sediment release help protect the fishery by mobilizing the sediment downstream.
The sediment release will pass naturally accumulated sediment to facilitate operations and maintenance of the diversion structure. However, the release and increased flow are coordinated to minimize impacts on the Shoshone River’s irrigators, recreators, and aquatic life.
The Bureau of Reclamation will retime operations and provide the flushing flow with the expectation that excess water will need to be released this spring. The flush will be accomplished without adversely impacting the expected water supply for irrigation.
Simultaneously, Willwood Irrigation District (in coordination with Willwood Workgroup Two) is planning a controlled elevated release of sediment from Willwood Dam. This release will also begin on April 11.
The meeting on the flushing and other Buffalo Bill Dam matters will be held at 1:00 p.m. on Friday, April 7, in the Yellowstone Building (rooms 103 and 105) at Northwest College.
Topics of discussion will be current water supply conditions, the 2023 snowmelt runoff forecast, and the 2023 projected reservoir operations.
Flows are expected to fluctuate according to the following schedule:
April 11
- 10:00 a.m. – Increase from approximately 700 cubic feet per second (c.f.s.) to 2,000 cfs
- 12:00 p.m. – Increase to 3,250 c.f.s.
- 2:00 p.m. – Increase to 4,500 c.f.s.
April 12
- 8:00 a.m. – Decrease to 3,500 c.f.s.
April 14
- 2:00 p.m. – Decrease to 3,000 c.f.s.
- 4:00 p.m. – Decrease to 2,500 c.f.s.
- 6:00 p.m. – Decrease to 2,000 c.f.s.
- 8:00 p.m. – Decrease to 1,500 c.f.s.
- 10:00 p.m. – Decrease to approximately 1,200 c.f.s. and maintain
The schedule may be modified depending on river conditions.
Flows will be high for this time of year, and the public is urged to use extreme caution during this period of flushing flows below Buffalo Bill Dam.
Flows of 4,500 cfs or more in the Shoshone River below Buffalo Bill Dam are not unusual. However, flows that high are typically during peak summer snowmelt runoff periods.
Buffalo Bill Reservoir near Cody has a storage capacity of 646,565 acre-feet and provides irrigation water to approximately 95,000 acres. The Bureau of Reclamation forecasts the reservoir to hold at least 700,000 a.f. of water – 94% of the 30-year average of 748,300 a.f.
