Heavy rains and a record snowpack are forcing the largest-ever water release from Gavins Point Dam near Yankton, South Dakota, which is causing Missouri River flooding. Releases from the dam are around one-point-one million gallons per second.
Dave Becker, operations manager for the U.S. Army Corps of Engineers at Gavins Point, says that flow rate is an estimate. “We have rating curves for our spillway gates that are calculated out but you really don’t know exactly for sure what you are releasing until the U.S. Geological Survey goes down to a fixed point and measures that flow,” Becker says. “There’s a little bit of trial and error any time we use these spillway gates. We have to do a little fine-tuning to get it right.”
Becker says the high flows require the Corps to do more inspections and day-to-day work. “There are different maintenance requirements with the increased flows,” Becker says. “Some of our protected shorelines below the dam need additional work. We have crews down there doing additional rocking and reshaping the rocking on both shores, just to protect our facilities as well as we can.”
Becker says the high flows from Fort Randall Dam upstream are creating challenges near the face of Gavins Point Dam.
“These high flows are really bringing a lot more debris into the lake and some of that’s accumulating in front of our power plant,” he says. “We have a crew in there with our barge, tug boat and crane removing the logs and the other material that’s accumulating.” The dam’s current flow rate, around 150,000 cubic feet per second, will stay at that rate until mid-August at least, the highest releases since the dam went into operation in the late 1950s.
By Jerry Oster, WNAX, Yankton