Brad and Heather Magnus had hoped the dike around their house on Hoge Island would keep back floodwaters up to 20.5 feet.
Unfortunately for the young couple, the Missouri River claimed their home of six years on Wednesday morning.
Swift floodwaters undercut the foundation of their house, causing the two-story part of their house and garage to sink into the water, nearly separating it from the rest of the house.
The Magnuses had evacuated their home by the first weekend of June, staying in a camper for a while before finding a place to rent, a family friend said.
They have two young children, she said.
Efforts by the Tribune to contact them were unsuccessful Wednesday.
Emergency management officials warn that further erosion to the riverbanks could do the same to other homes.
Mary Senger, Burleigh County emergency manager, said law enforcement had been unable to contact the owners.
"The residents had previously evacuated when voluntary evacuation was requested," Senger said.
Michael Gunsch, district engineer for the Burleigh County Water Resource District, said "scour hole" developed between two segments of riprap on the Missouri River.
"When the water overtopped the existing bank stabilization, it eroded the upper bank and undermined the foundation of the residence," Gunsch said.
"The risk for continued river bank erosion could result in additional failures along the bank, placing additional residences at risk," he said.
In an interview with the Tribune on June 2, Heather Magnus said she was angry and crying about the situation.
"Our whole life might be gone," she said then. "This is the only house my daughter has ever known."
(Reach reporter Brian Gehring at 250-8254 or firstname.lastname@example.org. Reporter Jenny Michael contributed to this story.)