Runoff forecast for Boysen Reservoir

There is no change in the snowmelt runoff forecast for Boysen Reservoir between March and April. Mahonri Williams, the resources management division chief for the Bureau of Reclamation’s Wyoming area office noted the April through June runoff prediction is still 1,100,000 acre-feet (af), which is 200 percent of the 30-year averaged of 540,000 af.

Even with the recent rain and snow in Thermopolis, Williams noted it would only affect those areas downstream on the Big Horn River.

Williams further explained outflows from Boysen Reservoir were at around 3,000 cubic feet per second but were stepped up to about 5,000 cubic feet per second, in an effort to move water out of the reservoir and prepare for the runoff. He noted there was rain and snow upstream of Boysen that caused an inflow to the reservoir.

The outflows were backed off a bit recently, down to 4,000 cubic feet per second, to accommodate for an inspection at the power plant. Williams said the inspection of the pipes carrying water to the generators had been scheduled for some time.

Outflows will be increased back to about 5,500 cubic feet per second later this week, Williams said, and people should expect the same levels in the river as they saw during the flushing flow at the end of March.