The U.S. Army Corps of Engineers reported that a full breach has occurred on the Missouri River Federal levee L-575 near Hamburg, Iowa, Monday morning, June 13.

Early assessments have determined that this fourth breach is just south of where the previous three partial breaches occurred last week, according to Omaha District Chief of Emergency Management Kim Thomas. The full breach is 50 feet wide and occurred in approximately five minutes. The breach is located near River Mile 552 in Atchison County in extreme northwest Missouri. The levee is in the Federal Program (PL84-99) and is operated and maintained by the non-federal sponsor. The corps constructed it in the late 1940s. 

The complete closure of a section of Interstate 29 between Hamburg, Iowa, and Rock Port, Mo., is expected within 48 hours due to the levee break and additional Missouri River flooding.

Meanwhile, the corps plans to release water from behind the Gavin's Point Dam west of Yankton, S.D. on Tuesday. Residents downstream in Council Bluffs, Iowa, St. Joseph, Mo., and other towns and cities have been stacking sandbags hoping to keep the river in its banks. A number of municipalities have evacuated residents in low-lying areas along the river. 

All State Emergency Management agencies have been notified, as well as the local emergency managers. The corps is working closely with Iowa and Missouri Emergency Management Agencies, as well as the County Emergency Managers, the National Weather Service and Federal Emergency Management Agency Region VII to ensure the safety of all in these areas.

The levee breach follows weeks of high flows and increasing releases from the main stem dams in Montana and the Dakotas. The corps continues to aggressively monitor and evaluate the inundation areas.

The corps has contractors in place that are working expeditiously to raise Ditch 6 levee near Hamburg by an additional 4 feet to provide a temporary flood risk reduction measure for the community of Hamburg, according to Thomas.

For Ditch 6, the fill on section one is 99% complete; section two is 90% complete and section three is 75% complete. The entire project will be finished on June 17. The corps is also coordinating with the Iowa and Missouri Departments of Transportation, and will add low spot fill on the right bank of the Nishnabotna River levee.