With the threat of flooding over, Interstate 29 in southeastern South Dakota is again open for traffic.
The interstate was closed at noon on Thursday so a levee could be constructed at Exit 4 as a protective measure against rising waters of the Big Sioux River. The river crested early Friday morning below forecasted level. The river crest, which came about 1 a.m. on Friday, was about 3.5 feet short of the forecast record level. South Dakota state officials say water didn't ever reach I-29.
The state says there are three main reasons why the river didn't rise as high as expected.
• 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.
Travelers are urged to visit Safe Travel USA or call 511 to check the latest road conditions in their area.
Below is video of the work to remove the levee from I-29.