Big Sioux River hits record level at Sioux City (2024)

NORTH SIOUX CITY — As the bloated Missouri and Big Sioux rivers barreled down on metro Sioux City, state and local officials took extraordinary steps Sunday to help protect residents, businesses and public infrastructure from the rising water.

Gov. Kristi Noem came to North Sioux City Sunday for a hastily arranged news conference to announce construction of an emergency levee across Interstate 29 in southeast South Dakota.

At 6 p.m., the state Department of Transportation shut down the interstate from Exit 2, at Dakota Dunes, to Exit 9, at Jefferson. The closed stretch, which includes both exits to North Sioux City, will remain closed until further notice.

"We're working towards getting that constructed, so that we can control as much of the flow of water as we possibly can," Noem said of the levee, which will consist of gigantic, self-supporting sandbags, strapped together and placed atop the north and southbound lanes under the Exit 4, or McCook Lake overpass.

The levee is designed to redirectexpected record floodwaters from the Big Sioux River away from North Sioux City and Dakota Dunes and into McCook Lake, said James Westcott, the Union County Emergency Management director. The lake itself, he said should not be overwhelmed because the excess water can later be pumped into the Missouri River.

As the depth of the Big Sioux rose above historic levels, authorities urged some residents of North Sioux City and Dakota Dunes to evacuate their homes.

By 10:30 p.m. Sunday, the Big Sioux River at Sioux City had reached a depth of 44.98 feet, shattering the record of 37.7 feet set a decade ago on June 20, 2014, according to data from the National Water Prediction Service. The supercharged river wreaked havoc, causing the collapse of a railroad bridge connecting Sioux City and North Sioux City around 10:40 p.m.

At Sioux City, the Big Sioux feeds into the Missouri River, which also has been rising rapidly in recent days. The Missouri reached a height of 30.7 feet at 11:30 p.m. Sunday, and was expected to peak at 31.1 feet at 7 a.m. Monday. That would be over 3 feetshort of the record of 35.3 feet during the months-long flooding along the river in 2011.

The historic 2011 flooding was triggered by record snowfall and near-record rainfall in western U.S. states, which forced the U.S. Army Corps of Engineers to release record amounts of water from upstream dams, including Gavins Point at Yankton, S.D.

Col. Robert Newbauer, commander ofthe Corps of Engineers' Omaha District, said Sunday torrential rains over the past week in north-central Nebraska, southeast South Dakota and northwest Iowa have overwhelmed the Missouri River system.

The Corps, he said, has done what it can to staunch the flow of water, by limiting releases from the Fort Randall and Gavins Point reservoirs. But, he added, the federal agency has little control over the smaller creeks and rivers that feed into the Missouri.

"We're talking about historic flows on unregulated tributaries into the Missouri River," he said.

Residents of some Dakota Dunes neighborhoods were forced to vacate their homes during the record 2011 flooding. The upscale planned community borders both the Missouri and Big Sioux.

On Sunday, local authorities encouraged Dunes residents to voluntarily evacuate until the swollen rivers recede. Late Sunday night, Union County officials also called for evacuations of residents living along the north shore of McCook Lake, from Exit 4 to Dakota Valley High School.

Westcott warned that residents who chose not to leave do so at their own risk.

"If you feel that you're in harm's way at your residence, and you see water coming at you, please gather your personal belongings and leave at that time," Westcott said. "The county is currently about maxed out on being able to do water rescues at this point."

Facing the dual threat of the swollen Missouri and Big Sioux rivers, Sioux City officials also took a number of protective measures in low-lying, river-adjacent areas Sunday. The city closed its boat ramp at Chris Larsen Park, as well the entire riverfront park.

By late Sunday afternoon, flooding from the Missouri River -- which was strewn with flotsam and debris, including trees and docks -- had inundated much of the city's riverfront trail system in Chris Larsen Park.

Local officials on Sunday also built an emergency levee along the Big Sioux River to protect residents of the city's vulnerable Riverside neighborhood. At a depth of 43 feet, the lower existing levels in Riverside would be in danger of being overtopped, if not sandbagged, according to the National Weather Prediction Service. Most storm drains would become submerged at a 38 foot or greater height, which the river has already exceeded.

The Sioux City Railroad Museum, which is located near the Big Sioux, closed to the public Sunday so volunteers could sandbag around the property, a popular tourist destination.

Upstream from North Sioux City, volunteers spent Sunday filling sandbags to reinforce a berm on the northeast side of Jefferson, hoping to keep the floodwaters from inundating the small town.

Not everyone was happy with the state of South Dakota temporarily shutting down Interstate 29 at the Iowa border.

Don Lantis, North Sioux City fireworks merchant, noted the closure comes less than two weeks before the July 4 holiday.

"There's not even any water there! Why do we have to close at 6 o'clock -- this is when I make my money," Lantis told Noem at Sunday's townhall-style meeting at the North Sioux City Fire Station.

Noem told Lantis to document his business losses should reimbursem*nt come available, though she noted she couldn't say for certain whether any would be available to him.

In brief remarks to The Journal after the meeting, Lantis cautioned that he wouldn't want to keep the interstate open if it would endanger people. "I want to protect the community, I've lived here my whole life," he said.

Military Road, another main route between Sioux City and North Sioux City, was closed at its intersection with Highway 12 Sunday due to Big Sioux flooding.

Noem said flooding damages in South Dakota will exceed $1.6 million, the statutory amount that must be hit in order to qualify for Federal Emergency Management Agency funding.

"Yesterday, I signed an emergency declaration, an executive order that will give us an evaluation of these storms but also allow us to start to pursue the documentation to pursue FEMA funding," Noem said.

"It's incredibly important that you document loss and that you document any financial impacts that people in the community have, so that we can keep that information in order to submit that FEMA declaration," she added.