(CNN) -- Civic-minded residents of Bismarck and Mandan, North Dakota, found there's nothing like a major flood to make new friends while filling thousands of sandbags.
As cities along the Missouri River brace for the onslaught, the "Sunday Sandbag Thrown-Down" in Bismarck resulted in 1,600 people producing about 300,000 sandbags in six hours, Burleigh County Commissioner Mark Armstrong said.
"The crisis is just beginning," Armstrong said Wednesday. "There has been a great community spirit."
Over the past few weeks, Armstrong, who has filed several CNN IReport photos and videos of the river and flooding, has been sounding the alarm over the threat to the community.
Already, 2,400 residents and 632 homes in the county have been evacuated, he said, adding most of the displaced are staying with family and friends.
"It's going to get worse," the official said. "People who never saw water in their basements are seeing water."
Such flooding hasn't happened here in nearly 60 years, before a system of Missouri River dams in North Dakota and South Dakota were in place.
In recent weeks, about 15 miles of emergency levees have been built in the capital area, according to Armstrong.
Upstream, at Garrison Dam, a peak release of 150,000 cubic feet of water per second is expected later this month.
Heavy rains and snow pack runoff could result in near-record flooding along significants portions of the Missouri River this year, officials have said.
Armstrong is concerned that a fast melt of an unusually heavy snow pack in Montana could have devastating consequences. Rainfall of 3 to 5 inches in July and August also could potentially destroy levees, he said.
Hundreds of National Guard members are in the area, performing levee patrols and other duties.
Across the Upper Midwest, townspeople are remembering the devastating Missouri River flood of 1952, which caused tens of thousands to flee.
The 1952 flood saturated parts of downtown Omaha before the U.S. Army Corps of Engineers constructed the current flood protection system, according to CNN affiliate KMTV.
The Missouri River in Omaha was at 30.38 Wednesday, slightly more than its peak during the 1993 flood, said National Weather Service meteorologist Rick Chermok. It is expected to rise to more than 32 feet by Tuesday, he said. Flood stage is 29 feet.
By comparison, the river was at a record 40.20 feet on April 18, 1952. It had an astounding water flow of 396,000 cubic feet per second.
The Army Corps of Engineers, which controls the dams, said Wednesday that it is committed to the Missouri River flood fight.
"This will be a long, sometimes frustrating and intense effort as the situation evolves and as we work together to avoid loss of life, minimize damages and help communities deal with the situation," said Brig. Gen. John McMahon, commander of the Corps' Northwestern Division. "The Corps is committed to doing its best in close collaboration with city, county, state and federal agencies as well as congressional representatives and others as we address this daunting challenge."
The Missouri River was 1.39 feet above flood stage Wednesday afternoon at Bismarck, with an increase expected later in the week.
CNN's Phil Gast contributed to this report.