Flood fighters in Fremont County, Iowa, are coping Thursday morning with a 200-foot breach of a Missouri River levee 2.5 miles northwest of Percival.
The waters could affect 24 homes south of the breach, officials said. Those homes already had been evacuated.
The break started sometime in the early morning hours, around 3 or 4 a.m., said Fremont County Emergency Management director Mike Crecelius.
National Weather Service forecaster Josh Boustead said the breach was discovered after the river level downstream at Nebraska City dropped about 6 inches, to 27.6 feet.
The U.S. Army Corps of Engineers is examining the breach. On-site reports show about 5 feet of water across 200th Street.
Local officials have said the water flowing through the breached levee could eventually join the floodwaters from failed levees south of Hamburg. That would increase the pressure on Hamburg's new levee, which has held so far.
MidAmerican Energy has been advised to cut power to all county homes and businesses west of Interstate 29.