Full reservoir being drawn down to prep for spring runoffApr 6, 2017 The Associated Press
BILLINGS, Mont. (AP) -- Water managers are drawing down Bighorn Reservoir in north-central Wyoming to make room for spring runoff after heavy snow fell in the Shoshone River drainage this winter.
The Bighorn River below Yellowtail Dam is running at 9,000 cubic feet per second, almost triple the average of 3,200 cfs for this time of year.
Bureau of Reclamation Montana area manager Steve Davies says the water level in Bighorn Reservoir is dropping almost a foot a day.
Montana Fish, Wildlife and Parks fisheries biologist Mike Ruggles says high water in the Bighorn River now could mean rainbow trout will lay their eggs in places that could be dewatered as river flows drop. The peak of the rainbow spawn is in May.
Ruggles says the additional water shouldn't affect brown trout, which hatch in March and April.
Yellowtail Dam, completed in 1967, stands 525 feet tall, creating a reservoir with a storage capacity of nearly 1.4 million acre feet of water.