Everyone, including the Corps of Engineers, thought Gavins Point Dam had been running at 150,000 cubic feet per second since Tuesday. Well, the Corps revealed last night that subsequent readings below the dam show it’s not quite there yet.
Here is what I wrote for today’s P&D:
Residents below Gavins Point Dam have not yet actually seen flows of 150,000 cubic feet per second (cfs), according to the U.S. Army Corps of Engineers.
That could soon change, said Jody Farhat, chief of the Missouri River Basin Water Management Division in Omaha, Neb.
“The rating curves for the spillways are based on engineering formulas,” she said during a Thursday conference call, noting it is not an exact science. “We’ve never used the spillways at these release rates before, so below all of the dams we’re getting flow measurements by the U.S. Geological Survey. We’re using those to verify our spillway rating curve. The measurements we’ve been getting below Gavins Point in the last couple days have shown that we’re releasing less water than what is being reported.”
Those reports show that releases at Gavins Point Dam may be as much as 4,000-5,000 cfs below 150,000 cfs.
“We are working with the project to make adjustments in those spillway gates in order to bring the releases to the level that we want them to be at,” Farhat said. “At Gavins Point, in particular, because that is such a small reservoir, being off a couple thousand cfs makes a lot of difference in the pool elevation.”
She added that measurements are being collected below Fort Randall Dam because it’s possible releases there are more than is being reported.
“We’re continuing to nail that down,” Farhat stated.