Big Sioux River crests below projections; Major flooding avoided
The Big Sioux River crested early Friday well below a record level, sparing residents of southeast South Dakota potentially major flooding, Lt. Gov. Matt Michels told reporters Friday afternoon.
The river crest, which came about 1 a.m. on Friday, was about 3.5 feet short of the forecast record level. Because no flood water reached Interstate 29, state crews were able to re-open the highway Friday afternoon. It had been closed on Thursday to facilitate levee building as protection against the anticipated record water level.
“We are extremely thankful that the flows were lower than forecast and residents of this area were spared major flooding,’’ Lt. Gov. Michels said. “In these situations, you do all you can to prepare for the worst. Then you hope for the best. Many, many good people worked diligently to prepare for the worst. Fortunately, that didn’t happen.’’
Early in the week, the forecast crest was about 109 feet. The actual crest was 105.6 feet. Three key factors contributed to the lower crest:
· Some of the water flowing down stream above North Sioux City dispersed out of the channel and into the floodplain because of a levee breach near Akron, Iowa. That reduced the amount of water that reached North Sioux City.
· Less rain than had been forecast fell Wednesday and Thursday over the Big Sioux basin.
· Less rain than forecast also fell in the watershed of the tributaries that flow into the Missouri River below Yankton. That, combined with the U.S. Army Corps of Engineers decision to reduce flows from Gavins Point Dam near Yankton, cut the amount of water flowing down that channel. That resulted in a somewhat lower flow where the Missouri and Big Sioux rivers meet below North Sioux City.
“Sometimes, when you work hard to protect yourself and your loved ones, you also catch a break,’’ Michels said. “We caught two or three, and I can’t tell you how good that makes me feel.’’
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