Exhausted residents of Fargo, N.D., were to suffer another setback Monday as a harsh winter storm prepared to barrel into the area, carrying up to 14 inches of snow and wind-whipped waves that could worsen the flooding.

The week began in Monday with much of Fargo shut down, school called off for the entire week and many businesses keeping their doors closed. And the massive sandbagging effort began winding down after thousands of volunteers turned out around the clock to fill up bags. Fargo filled 3.5 million sandbags, and has an inventory of 450,000.

"We're a pretty hardy lot," Cass County Sheriff Paul Laney told FOX News. "We're used to this. Yes we're in a major flood fight and now a second major snowstorm is going to hit during it, but we'll suck it up. You can sit and whine about it or you can do something about it. We'll get 'er done."

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"We're putting up a fight throughout the Red River Valley," Laney added. "Mother Nature gave us a sucker punch but in the end we're gonna hit her back."

Engineers who were watching the flooding weren't worried about the snow because it's unlikely to melt soon. They were concerned about waves that could crash against the sandbag levees, further weakening them. The forecast called for the storm to move in by early afternoon Monday and last until Tuesday evening.

The higher the wind speed, the higher the threat, Jeff DeZellar, a spokesman for the U.S. Army Corps of Engineers, said Monday.

"The forecast that we saw was 25 mph or more, and certainly that's enough wind to create some wave action on the river," he said.

The National Guard was placing a layer of plastic-type sheeting over the levees to help them hold up against high waves. "It's important to get as much work done as we can before the storm comes," DeZellar said.

The Red River dropped to 39.21 feet early Monday -- less than record highs set earlier in the week but still nearly 22 feet above flood stage. City officials have said they would breathe easier when the river falls to 37 feet or lower, expected by Saturday.

"The difficulty with an epic flood is nobody has been through it before," said city commissioner Tim Mahoney. "You can't ask someone, 'Hey, what's going to happen next?"'

It will be more waiting to see if the levees -- quickly constructed last week by Fargo's men, women and children -- can hold firm.

The flood was caused by an enormous winter snowfall that melted and combined with more precipitation to send the river to record levels. The river flows from south to north through the tabletop terrain of North Dakota, providing few opportunities to drain.

Snow was moving toward Fargo from the south-central part of the state, where a slow-moving blizzard brought more than foot of snow Monday. The storm came a week after snowmelt and a Missouri River ice jam caused major flooding. Residents have been told to keep their sandbags handy as a precaution.

Fargo officials also warned people to stay away from the dangerous river. The Coast Guard caught a man paddling a canoe down the river who apparently jumped a levee to get into the water, and authorities vowed to arrest anyone who commits such a crime.

Police also say a 49-year-old woman was arrested on suspicion of drunken driving after she attempted to drive up a clay levee near the flooded Red River. Capt. Tod Dahle said the woman was very close to going into the river

On Sunday, helicopter crews sought to fortify the levees in Fargo by dropping 11 one-ton sandbags near vulnerable areas of the dike system. Above them, an unmanned Predator drone from the Grand Forks Air Force Base flew to watch flood patterns and ice floes. North Dakota has more than 2,400 National Guard troops engaged in the flood fight across the state.

The helicopters focused on an area near a middle- and high-school campus that was inundated after floodwaters briefly breached a levee Sunday, causing considerable damage before officials quickly pumped out most of the water.

School officials also frantically raced to rescue a cockatiel, parakeet, tortoises, iguanas and snakes kept at the school as part of its science program.

"The main event is right now, while we have this higher water. And it ain't over till it's over," said Rep. Earl Pomeroy. "And it ain't gonna be over until several days from now."

While officials say they have limited the damage to a small number of homes within Fargo's city limits, several outlying rural areas have seen significant flooding. Cass County sheriff's deputies toured some of these areas Sunday in giant National Guard vehicles, offering assistance to stranded residents.

They encountered a woman whose prescription drugs were about to run out, people who trudged out of their homes in waders and a couple who gladly got a lift out of the neighborhood on the Guard truck. All the while, huge sheets of ice floated over people's yards and lawn furniture and children's toys could be seen stacked up behind sandbag lines.

Public works officials were closely watching to make sure water and sewer systems remained safe. Fargo's water and sewer plants are right next to the river, and are protected by a secondary dike system.

"If we lose water and sewer, the city is uninhabitable," said Fargo City Administrator Pat Zavoral.

Moorhead, a city of 30,000 directly across the river in Minnesota, also was fighting to hold back the river. Moorhead Mayor Mark Voxland said he was concerned but still optimistic about how long his city's dike could last against the pressure of the river water.

Flooding statewide was blamed for two deaths, in central and western North Dakota, in what health officials said were apparent heart attacks brought on by flood-prevention exertion.

Fargoans gathered Sunday at several different church services, praying in thanks for the city's luck so far and seeking protection in coming days.

"At a time like this, we need to call on God's providential assistance," said pastor Bob Ona of Fargo's First Assembly of God church. "All of you have been heroic in your efforts. All of you have been pushed past the wall of weariness, exhaustion and numerous frustrations in order to do the right thing -- help people in the name of the Lord."

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FOX News' Rick Leventhal and The Associated Press contributed to this report.