South Dakota officials share photo of flooding North Sioux City could have seen without levee

NORTH SIOUX CITY, S.D. (KCAU) — South Dakota officials believe that building the levee on Interstate 29 at North Sioux City helped save the city from flooding. They also shared two timelines of how officials were responding to storms and flooding in North Sioux City.

Using information from the South Dakota Flood Information System, the governor’s office provided two pictures of flood models for southeast South Dakota and North Sioux City. The first was a picture of what flooding could have been in North Sioux City without the construction of the levee on Interstate 29. It shows extensive flooding in the city.

A second photo shows that same flood model but with the levee in place. The governor’s office said that by comparing the two, it can be seen how much of North Sioux City and its residents were protected from flooding. Below you can see the comparison between the two flood models.

The South Dakota Department of Transportation closed Interstate 29 from Exit 2 to Exit 9 at 6 p.m. on June 23. Officials did the to construct the levee at exit 4 that connected with another levee. This was taking place as officials were expecting the Big Sioux River to crest overnight. That levee directed water into McCook Lake, causing catastrophic damage to the neighborhood.

In addition to the photos, the governor’s office also shared timelines from the SD Department of Public Safety and the Governor’s Office of actions that were taken.

The South Dakota Office of Emergency Management (OEM) first reached out to counties emergency managers on June 21 after the heavy rain from the night before. The DOT also put out a release saying that many highways were being impacted by flooding as they issued a warning to not travel.

Below is a playlist of drone video of McCook Lake from Sunday, June 30 provided by Giraffix, Inc.

The U.S. Army Corps of Engineers also announced on that Friday that they would be lowering its releases at Gavins Point Dam at Yankton, S.D. due to the excessive rainfall and to offset flooding downstream.

On the morning of Saturday, June 22, it was projected that the Big Sioux River at Sioux City would crest at 38.4 feet, 0.7 feet over the previous record. Noem issued an executive order that afternoon declaring an emergency for southeast South Dakota counties affected by flooding.

On the morning of Sunday, June 23, the Big Sioux River was at 35.14 with it then forecast to crest at 42.2 feet later that night. Noem held a press conference that afternoon calling for a voluntary evacuation of the Dakota Dunes. She also announced that there had been one death due to flood waters. Later that afternoon, Officials put out the notice that Interstate 29 would close and they were installing a levee. Multiple state departments were also assisting in multiple ways.

Later that night, believed to have happened at 8:21 p.m., a text alert was sent out to McCook Lake residents. The Big Sioux river would peak that night at 10:30 p.m. hitting 44.98 feet, more than seven feet above the record.

Below is the full storm response timeline from the governor’s office.

Below is the full response timeline from the South Dakota Department of Public Safety.

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