Scientists have attributed the uptick in flooding to increased rainfall in the Midwest, an effect of climate change, and the continuing efforts to constrict the river. In an ever changing patchwork of protection, cities and towns have long sought new ways to keep the water away. Burlington, Iowa, has worked in recent years to install a floodwall. In Illinois, some rural levee districts have been accused of building beyond their authorized height, a point of bitterness for those downstream.

“There’s always going to be winners and losers when it comes to levees,” said Jonathan Remo, an associate professor of geography at Southern Illinois University Carbondale. “When you create big levees, you’re pushing water onto somebody else.”

Heavy rains expected this week could worsen problems along the Mississippi River, which has already been above flood stage for well over a month in some areas. Some people who live along the river said they believed they were at a tipping point — a moment when the entire region needed to rethink the wisdom of having so many levees, especially in rural areas with few people.

“You’ve got hundreds of miles of waterway leveed off that probably can’t stay like that,” said Colin Wellenkamp, the executive director of the Mississippi River Cities and Towns Initiative, which represents municipal governments on the river.

Grafton’s laissez-faire approach to flood control is part fiscal necessity and part business strategy. Spending tens of millions of dollars on a floodwall is not practical, Mr. Eberlin said, and doing so would jeopardize Grafton’s main appeal to tourists, many of whom come from St. Louis, about 40 miles to the south, to be near the water. The town’s strategy also has environmental benefits, according to experts who warned that the competition to build bigger levees elsewhere is dangerous and expensive.