Recent warm weather has caused Keyhole Reservoir to rise over a 20 inches in elevation in the last week bringing it to full elevation of 4099.3 feet on Tuesday.
“Keyhole Reservoir is at its highest level since June of 1999,” said Jeff Nettleton, Chief of Facility Operation and Maintenance and Engineering Services for the Bureau of Reclamation’s Dakotas Area Office.
When the reservoir becomes full, a small amount of water will begin to flow out of the uncontrolled spillway into the Belle Fourche River. Reclamation will also begin a small controlled release from the outlet works at that time. These initial releases from the spillway and outlet works will be in the range of 50 cubic feet per second (cfs).
Inflows for water year 2012 at Keyhole are 143 percent of average. The reservoir elevation at the end of February was the third highest in 59 years of historic record. No releases from Keyhole are being made at this time.