A levee in Atchison County MO. has breached and water is coming through, threatening northern Atchison County and Hamburg Iowa.

Atchison County officials announced the breach and asked for evacuations for those who have not evacuated already north of the Nishnabotna River.

The breach was reported just before 11:30 this morning about 1.25 miles south of the state line along Levee L575. The beach initially created a hole 50 feet wide, but in an afternoon news conference, the Army Corps of Engineers said the breach had reached a width of approximately 300 feet.

Hamburg Iowa is protected by a secondary levee. According to Omaha District Chief of Emergency Management Kim Thomas, the current temporary levees were designed to an elevation of 916 feet, which floodwaters are expected to reach by Wednesday. Levee district officials plan to add a new product to the top of the temporary levees to provide a new elevation limit of 919 feet. The Corps predicts a new water-surface elevation topping out at about 918 feet.

The levee sponsor has requested technical assistance and will proceed with a partial breach to a downstream portion of the levee to minimally delay the time in which the area will elevate to 916 feet.

Thomas said levees can be breached for a variety of reasons and, at this point, it is too early to determine the cause of Monday’s full breach. The breach Monday follows weeks of high flows and increasing releases from the main stem dams in Montana and the Dakotas.

According to a news release, the Corps has contractors in place who are working to raise the Ditch 6 levee near Hamburg to a total of eight feet to provide a temporary flood-risk reduction measure for that community.

The National Weather service has issued a flash flood warning for the area. The levee was built by the Army Corps of Engineers in the late 1940’s.

Flood waters are expected to reach Interstate 29 and Hamburg sometime tomorrow, according to the National Weather Service.