FREMONT, Neb. - Chris Sewall stood with a push broom in front of an emergency shelter he manages for at-risk children, sending water sloshing down the front steps Wednesday afternoon. It had been nearly a week since he had to evacuate 10 teenagers from this facility, and the floodwaters had finally receded.

The basement still had about 4 inches of water, but Sewall was optimistic.

"We look around," he said, gesturing to neighboring houses where soggy furniture had been hauled into muddy front yards. "We're feeling pretty lucky."

Piles of damaged appliances, water-stained upholstery and black garbage bags stretched toward the roofs of single-story houses that had been flooded when rain and melting snow produced record-high river levels. One homeowner had placed a detached door under a sump pump's downspout, a makeshift ramp to redirect the flow into the driveway.

Communities across the Midwest are facing massive cleanup efforts after last week's late-winter "bomb cyclone" caused at least four deaths, forced the evacuation of entire communities and drenched vast tracts of land with icy and often polluted water. Nebraska's emergency agency set the estimated cost of the destruction at $1.3 billion on Wednesday, including $400 million for dead livestock, $440 million in lost grain and $439 million in damaged infrastructure.

Vice President Mike Pence promised prompt federal aid when he surveyed the destruction Tuesday and visited a shelter in Nebraska. But even as the floodwaters receded in some places, residents elsewhere tried to gauge the eventual impact of the relentless southward surge.

Communities continued to issue new disaster declarations, putting three-quarters of Nebraska's counties under states of emergency. Officials in Iowa, Wisconsin and Mississippi have done the same, under threat from the historic flooding around the Platte and Missouri rivers.

The stricken states issued warnings to residents about the dangers of driving around flood barricades, and provided checklists for cleanup supplies and information on disposing of dead livestock and where to obtain mental health support.

But for many in the devastated region, the start of the cleanup was coupled with a realization that the recovery could take years, amid warnings that the current infrastructure of dams and levees will not be adequate to protect them from the increased frequency and severity of flooding that comes from climate change.

"It will last for months," said Tom Waters, president of the Missouri Levee and Drainage District Association.

In coming weeks, Waters expects, snow melt will add to the torrents still topping levees and inundating farmland, homes and businesses as they churn toward the Gulf of Mexico.

In Lincoln, Nebraska, officials warned that floodwaters may have contaminated private wells and provided testing kits, recommending that people boil or add household bleach to their water and strain cloudy water through clean cloth.

With the wells for the city's drinking supply near Ashland, Nebraska, still flooded, residents have been asked to cut their water usage in half. Along the streets, temporary signs flash messages: "Every drop counts."

At Russ's Market, just south of the state Capitol, cases of bottled water were stacked high. Cashiers asked customers whether they were willing to round up their totals to give the change to flood relief efforts.

Small towns used the resources they had to dig out from under the flood's aftermath. In Verdigre, Nebraska - population 575 - a week had passed since ice-cold waters filled basements and seeped into businesses. People were at work Wednesday, tearing out damaged interiors, vacuuming up the damp and smelly detritus and drying whatever belongings seemed salvageable.

The village had invested in a truck with a new blade for snow removal last fall. Now it was proving its worth, hauling in 10 loads of sand and gravel to repair streets gouged by floodwater.

"It's a dandy little truck," said Dave Wickett, a former chairman of the village board of trustees. "We will bounce back."

But some Nebraskans worried about their ability to overcome the damage. Curt Richey and his wife, Sherrie, were ready to put their house on the market in Inglewood, Nebraska, last week when water surged into their neighborhood.

"We had all the paperwork filled out and was one day away from sticking a sign in the yard," Richey said.

When they returned days later, their finished basement - what Richey had hoped would be one of the home's main selling points - had 5 feet of standing water. His grandmother's antique hutch lay toppled and face down. On Wednesday, the sump pump was humming, but the piece of antique furniture was still floating in more than a foot of brown water.

"Nobody is gonna buy this place now," Richey said, his eyes welling up. "If the levee ain't fixed, you're just sitting on a sand bar. That's all you're doing."

Many parts of the vast watershed have yet to feel the full force of this first round of flooding.

South of Saint Joseph, Missouri, Lanny Frakes, president of the Halls Levee District - which covers more than 18,000 acres and has never been breached since it was built in the 1950s - said farmers in the bottomlands had been sandbagging land that stayed so soggy through last winter that some crops could not be harvested.

"This is the earliest flooding I've ever seen in this area," Frakes said, looking ahead to the threat of deluges in April caused by snow melt from the plains, then in May and June from the mountains, and then thunderstorms in the summer.

Frakes was monitoring the situation closely and meeting with representatives from the Army Corps of Engineers and other levee districts on Wednesday, including the Rushville-Sugar Lake Levee, which protects about 8,500 acres. He expected the Missouri River to crest late Thursday or early Friday - and if the current projections hold, the levees will be overtopped in several places.

"It's just what it is," Frakes said.

The soil has to dry out, Frakes said, for repair work to be done, including rebuilding highways, filling the cavernous ravines the water channels cut through fields, and removing vast drifts of infertile sand that it churned up from the turbulent river's bed.

Frakes is critical of recent policies that he said had put environmental concerns such as saving the habitats of endangered species ahead of flood control and farmers' economic needs.

"We have a loaded gun pointed at our head," said Frakes, anticipating the river's coming crest. "Nobody has pulled the trigger yet."

The Washington Post’s Annie Gowen in Washington contributed to this report.