Residents in Valley City, population 6,500, were sandbagging Wednesday after forecasters said the Sheyenne River was coming in higher and faster than expected. The crest is now set for Thursday instead of Friday, and two feet higher than initially feared.
The town was getting offers of help from nearby Fargo, which only saw minor flooding before the Red River crested earlier this week.
Officials say the water is slowly dropping north of Fargo, where unprecedented overland flooding has left many rural residents isolated. Five Fargo homes sustained damage from the flood, most from pump failures.
In northwest North Dakota, meanwhile, authorities were weighing whether to drop half-ton sandbags from a National Guard helicopter to shore up a dam that stands between 30 endangered homes and the swollen Des Lacs River.
State Homeland Security Director Greg Wilz called it a "crapshoot'" because engineers say the sandbags could do more harm than good.
"At this stage of the game, it's more art than science," Wilz said.
About 200 people living near the river in Burlington had been advised to evacuate because the dam might fail, leading to a 2-foot to 3-foot rise on the river.
After touring the area, Gov. Jack Dalrymple said he was "amazed" at the flooding conditions.
"I wish we could say with certainty what's going to happen in the next day or so," he told worried residents in a packed Burlington city hall.
The National Weather Service issued a flash flood watch for the area on the west edge of Burlington, a city of about 1,200 people, saying a dam failure could lead to a 2-foot to 3-foot rise in the river.
Assistant Police Chief Bill Hunt said he was not aware of anyone leaving their home yet, and that officials in a boat already have rescued one person whose home was surrounded by floodwaters.
Authorities placed a video camera on the dam to monitor water levels and were prepared to immediately contact affected residents if the structure burst.
The dirt-and-rock Burlington Dam No. 1 was built in the 1930s to help control the river's flow as it meets the Souris River and flows around Burlington. Authorities have been trying to plug holes in the dam with sandbags but can no longer access the site for safety reasons.
Todd Sando, an engineer with the state of North Dakota, said "there is a very high potential it could wash out."
Hunt told The Associated Press that Federal Emergency Management Agency officials were bringing equipment to monitor the dam. Fire Chief Karter Lesmann said the city had about 3,000 sandbags on hand for use in the town.
An evacuation could become mandatory if the dam were to fail or if officials became certain it was about to fail, Hunt said. He said it was difficult to predict what sort of damage might result from a failure or how much time people would have to prepare for high water.
"It just depended on how it failed," he said. "If it completely failed, probably not much time ... if it eroded, we might have an hour or two."
Robert Kibler and his wife, Alex Deufel, decided to leave their home near the river on Tuesday but returned Wednesday to move their collection of 7,000 books to a main floor.
"We really need a new dam," said Kibler, who like his wife is a professor at Minot State University. "The one here is old. Hopefully this will spur someone to take action."
Josh Ishmael and Will Mathews, who are in North Dakota working on an oil pipeline, said they had been shoring up their boss's home with sandbags and a dike. They became stranded on the dike overnight this week and said they had to burn wood from a new deck on the home to keep warm, before authorities brought out a boat to rescue them.
"We've never seen anything like this in Oklahoma," Ishmael said.
Hunt said officials have set up barriers they think will keep the city limits of Burlington safe from the Des Lacs River but that the high-flowing Souris could be a threat.
"That could back up into Burlington," he said. "It's so hard to say which way the water will go."
Simosko said the Des Lacs River might begin to recede late Wednesday.
"Two days from now everything could be just fine and this just a bad memory," Hunt said. "But if the dam breaks loose and water from the Souris backs up, it could be more of a problem."