01:03 ‘Total Disbelief’: Families Isolated as Isaias Washes Away Only Road to Their Homes Heavy rain and rising waters washed away a private road in Huntingtown, Maryland, stranding 7 families on the wrong side of the break.

At a Glance New evacuations were ordered overnight in Minnesota and Wisconsin.

A Nebraska farmer was killed trying to rescue a stranded motorist.

A Nebraska nuclear plant is threatened.

A 'compromised' dam forced evacuations along the Niobrara River.

A third of the 24,000 residents in Norfolk, Nebraska, were ordered to evacuate Thursday.

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Flooding in parts of the Midwest has left one man dead threatens a Nebraska dam and nuclear power plant as heavy rains mixed with a melting snowpack swell waterways to historic levels.

An unidentified Nebraska farmer was killed Thursday after the tractor he was using to try and save a stranded motorist was carried away by floodwaters, the Omaha World-Herald reports. The incident occurred at Shell Creek near Columbus, in eastern Nebraska.

Ericson Dam in north central Nebraska is at risk of failing as the Cedar River continues to rise, according to a report by the National Weather Service.

Officials in Boone County, downstream from the dam, also warned of the "imminent failure " of the dam, Boone County News reported.

Both agencies are warning impacted residents to seek higher ground.

In Nebraska, a utility company was placing sandbags around a threatened nuclear power plant Thursday as the Missouri River continued to rise, the Omaha World-Journal reports.

Mark Becker, spokesman for the Nebraska Public Power District, told the newspaper that should the river hit the level of 45.5 feet as projected by the National Weather Services this weekend, the Cooper Nuclear Station, which accounts for 35 percent of NPPD's power, will have to be shut down.

(MORE: Flooding Continues in the Plains, Midwest As Snow Melts; Severe Threat Waning in Midwest, South)

Becker noted that should the plant shut down, DPPD will be able to get power elsewhere and they don't expect the closure to lead to outages.

On Thursday, DPPD lost another small electrical plant when the Spencer Dam failed at the Niobrara River and caused a large ice floe to jam a hole in the building. Workers inside the building were uninjured, Becker told the newspaper. The failure also forced the evacuation of dozens of residents along the river.

The Knox County Sheriff's Office posted a notice on Facebook Thursday morning warning residents, noting that the dam had been "compromised."

The Nebraska State Patrol tweeted a photo showing where a bridge on Highway 281 over the Niobrara River south of the dam had washed away.

The widespread flooding prompted Iowa Gov. Kim Reynolds Thursday to sign an emergency disaster proclamation that allows state resources to be used in response to flooding in the state. Nebraska Gov. Pete Ricketts had issued an Emergency Declaration on Tuesday.

So far, 19 locations across the Midwest have set new flood crests, says weather.com senior meteorologist Jon Erdman. These include eight locations in both Iowa and Nebraska, two in South Dakota and one in Wisconsin. Erdman noted that the flooding will continue through the weekend and highlighted a possible flood record of more than two feet on the Missouri River at Brownville, Missouri.

Here's how the flooding is impacting Midwestern states:

Iowa

Just before 11 a.m. Thursday, the residents of Hornick in western Iowa were ordered to evacuate immediately because of a levee breach on the West Fork of the Little Sioux River.

"They gave us about 10 minutes, so you just grab the things you need the most ," Catie Newman told the Des Moines Register.

Sheriff's deputies and fire fighters went door to door warning the residents , the Sioux City Journal reported.

(MORE: Long-Awaited Pattern Change Will Bring a Break in Parade of Storms)

Newman, who is disaster response coordinator for the Iowa United Methodist Church and pastor of churches in Hornick and Salix, said tree branches and chunks of ice were floating across the plains around the town of about 200 people about 30 miles southeast of Sioux City. "Many of the fields are filled with water as far as the eye can see," she said.

"Really all we can do right now is take care of one another," Newman told the Register from the Salix church where she planned to stay Thursday night.

To the north of Hornick, the town of Molville was also inundated by flood waters.

Also in Iowa, flooding closed several highways, including the closure Thursday of Interstate 680 near Council Bluffs and a portion of Interstate 29, the Associated Press reports.

Several breached levees prompted evacuations in Missouri Valley, Iowa, the AP also reports. Parts of the city were already underwater.

Nebraska

Plattsmouth, Nebraska, residents were told to restrict water use after the Plattsmouth Water Treatment Plant was inundated by rising flood waters from the Missouri River. The plant was shut down and a water emergency declared , WOWT-TV reported.

A third of the 24,000 residents in Norfolk, Nebraska, were ordered to evacuate Thursday after the city's levee system "neared its top," city officials said. One person was reported missing after their car was swept away, News Channel Nebraska reported.

“Our ability to respond to emergencies is limited. This is a real threat for us. If that levee is breached, the water is trapped in town and we’ll see flooding like we haven’t seen since 1965 and there’s nowhere for the water to go,” Norfolk Public Safety Director Shane Weidner said.

Ten people were trapped on Channel Road in Norfolk, and rescue crews had to use a boat to reach one home surrounded by flood water, KETV reported.

Earlier Thursday, people were rescued from cabins along the Platte River in Yutan, Nebraska.

A hospital and nursing home were evacuated in Genoa, Nebraska, after the Loup River overtopped an intake structure at the the Loup Power Division, New Channel Nebraska reported.

The Nebraska State Patrol was assisting with evacuations but had trouble accessing the community, News Channel Nebraska reported. The station also notes there are "no safe evacuation routes."

Residents along the Platte River from Schuyler to Ashland, Nebraska, were told to evacuate at 11 a.m. , the Omaha World-Herald reported. The National Weather Service warned that a surge of water was moving down the river because of an ice jam breakup.

"Anyone living near the Platte or in the floodplain needs to get out before it’s too late," Dustin Wilcox, a spokesman for the Nebraska Association of Natural Resources Districts, told the World-Herald.

(MORE: El Niño Conditions Strengthen, Could Last Through Summer)

Highways 30 and 36 were closed by flooding in Washington and Douglas counties, the Washington County Sheriff's Office said. Water rescues were taking place in Arlington, Blair, Fort Calhoun and Kennard, the sheriff's office said.

Missouri

Officials in Holt County in northwest Missouri recommended that people living in low-lying areas near the Missouri River evacuate. Dozens of roads were closed in that corner of the state because of flooding.

A woman who fell into the swift-moving Missouri River in Bridgeton, Missouri, on Wednesday night had to cling to the roots of a tree until rescuers could pull her from the 40-degree water , the St. Louis Post Dispatch reported. The woman, who was not identified, was walking her dog when she slipped off a bank and couldn't climb back up. She was in the water for about 35 minutes, the report said.

"It was pretty miraculous she held on the way she did," Assistant Chief Jim Usry of the Pattonville Fire Protection District said.

Wisconsin

Some Brown County, Wisconsin, residents, including some of the 14,000 residents living in the village of Bellevue, were ordered to evacuate overnight as floodwaters along the East River continued to rise, reports NBC26. A full list of closures and evacuations can be found here .

Minnesota

An estimated 1,000 residents at a mobile home park in Jordan, Minnesota, were urged to evacuate late Thursday after an ice jam on Sand Creek caused the creek to overflow its banks and onto the property, KSTP reported. The evacuation was voluntary, authorities told the station, noting that there is no drowning risk involved.