BROWNVILLE, Neb., June 20 (UPI) -- The rising Missouri River prompted the Cooper Nuclear Station near Brownville, Neb., to declare a "notification of unusual event," plant officials said.
The designation, anticipated by plant operator Nebraska Public Power District, was made Sunday when the river there reached a height of 42.5 feet, or 899 feet above sea level, the Omaha World-Herald reported. The notification is the lowest and least serious of four emergency classifications developed by the Nuclear Regulatory Commission for nuclear power plants.
The Nebraska Public Power District said in a statement the plant is operating safely and there is no threat to plant employees, who are monitoring the water levels. If the river level increases to 45.5 feet, or 902 feet above sea level, the station would be taken offline as a safety measure.
The Fort Calhoun nuclear plant, 20 miles north of Omaha, was shut down April 9 for refueling and hasn't been restarted because of pending flooding.
President Obama Sunday declared an emergency exists in Nebraska and ordered federal aid to supplement state and local response efforts in the area affected by the flooding, the White House said. The declaration also authorizes the Federal Emergency Management Agency to coordinate disaster relief efforts and provide assistance.
In Missouri, the Missouri River washed over and broke through levees in the northwestern part of the state, prompting authorities to urge about 250 residents to evacuate Sunday, CNN reported.
The river breached levees at two points and slopped over barriers at two other locations near Corning, Mo., about 100 miles north of Kansas City, the Holt County Sheriff's Department said.
Upriver, evacuation advisories were issued for 200 to 250 people in areas west of Interstate 29, said Mark Manchester, the deputy emergency management director in Atchison County. He said water spilled over the levees Sunday and already eclipsed the county's previous record mark, set in 1993.
"We're in uncharted waters here," Manchester told CNN.
Across the state line in Hamburg, Iowa, where two levees failed last week, the river was expected to crest at 10 feet over flood stage in the coming days, emergency officials said.