Two levee breaches just south of Hamburg, Iowa, prompted authorities in Fremont County to issue a mandatory evacuation order Sunday for residents in southern Hamburg.
The Fremont County Emergency Management Office said about 240 residents — roughly 20 percent of the town — were ordered out of their homes following the downstream levee breach in Missouri's Atchison County.
Record outflows from upstream reservoirs have swollen the Missouri River this year, adding considerable pressure to a vast system of levees erected along the river's banks.
Early assessments determined the second partial breach near Hamburg and the damaged areas are likely to fully breach as water levels continue to rise.
As a temporary measure to reinforce the levee to delay a full breach, the Iowa National Guard on Sunday was using a Black Hawk helicopter to drop 1,000-pound sandbags onto the affected part of the levee. Authorities had removed heavy equipment and workers from the area because of concerns about the levee's strength.
The situation in southwest Iowa reflects part of authorities' biggest concerns. Although the stream of river water leaking from the levee into nearby fields was minimal Sunday, authorities worry that part of a community's infrastructure could be inundated.
“We're going to be very much in a surveillance mode to ensure that there isn't any damage that occurs to the levee systems,” said Ted Streckfuss, an engineer with the U.S. Army Corps of Engineers. “We're going to have to be very vigilant for the upcoming months, because public safety is our foremost priority.”
Atchison County Emergency Manager Rhonda Wiley said Hamburg residents were not in a life-threatening situation at this time, but the situation was expected to worsen with increased flows.
The second breach occurred when the levee collapsed along a 10- to 15-foot space, said Kim Thomas, chief of the corps' Omaha office. The collapse filled in on itself, blocking the Missouri River from flowing fully past the levee, so flooding on Sunday was minor.
Thomas said, however, that the collapsed area's ability to hold back the water was precarious and the sandbagging effort was not expected to be a permanent solution.
The corps also identified a concern with a levee near Brownville, Neb., and is working on a solution there, she said.
Levees can be breached for a variety of reasons. It was too early to determine, corps officials said, what caused the two breaches near Hamburg.
“People's safety is our No. 1 concern, so we want to stress how important it is for the public to stay off of these levees as we continue to assess the risk,” said Col. Bob Ruch, Omaha District Commander for the corps.
An earlier blowout about 100 feet from the latest rupture near Hamburg was repaired, said the Atchison County Emergency Management Office. The Army Corps of Engineers and volunteers had worked throughout Saturday and into Sunday to repair that breach.
The latest levee leak is about one mile south of the Iowa-Missouri border and approximately 5.25 miles southwest of Hamburg.
The topography in the area is flat, and authorities estimated that a significant breach would send water toward Hamburg.
Workers were busy Sunday at another levee that protects Hamburg. Contractors were to raise the levee by five feet to further reduce the town's flood risk, Ruch said.
The National Weather Service in Valley, Neb., extended a flash flood warning for Fremont County through Monday afternoon because of concerns over the levee's stability. Interstate 29, in the vicinity of the leak, was not affected.
“We take any type of situation like that very, very seriously because of the potential repercussions,” Streckfuss said.
“A failure of the levee in this area would flood Interstate 29 in the vicinity as well as send flood waters toward Hamburg,” according to the weather service flash flood warning that was updated Sunday.
Mike Crecelius, Fremont County's emergency management director, said the Hamburg evacuation was going well.
But he cautioned: “The levee's already breached in two places, and the Corps isn't certain how well or if it will hold.”
The levee was constructed by the Corps of Engineers but is operated and maintained by local authorities.
World-Herald staff writer Susan Szalewski contributed to this report.
Contact the writer:
402-444-3131, sam.womack@owh.com
Aerial video from the Hamburg Iowa area Sunday afternoon. :
Footage of the water released from Gavins Point Dam in South Dakota:
Video of the volunteers filling and stacking sandbags at the Mid-America Center on Saturday:
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