As record-breaking floods swamped the Midwest this week, dozens of levees built to protect people from flooding have catastrophically failed. The destruction has caused billions of dollars in damage and exposed weaknesses in the country’s piecemeal approach to flood management.

Now, with an inland sea of water surging downstream, towns along the Missouri River and beyond are stacking up sandbags and wondering whether their own levees could be the next to fail. At least 50 levees have been breached or overtopped by rivers engorged with late-winter rains and snowmelt, according to the Army Corps of Engineers.

The failures have raised questions among residents about the durability of the flood system and renewed criticism from conservation groups who say that America’s scattershot approach to flood control and development near rivers is simply setting the stage for future disasters.

Q: How bad is the damage?

A: Counties in Iowa and Nebraska that were left underwater when the earthen walls of their levees caved in say that they have never seen such widespread damage to their flood-protection systems.

Some estimated the repair costs in the hundreds of millions or billions of dollars, and said they had no idea how their rural communities could afford to rebuild them. Or whether they even should.

“It was catastrophic,” said Larry Hurst, director of emergency management in Mills County, Iowa, where there were eight breaches. “How are we going to fix it and who’s going to fix it? The tax base isn’t there to build a whole new levee. What are we going to do?”

Q: Who oversees the levees?

A: About 100,000 miles of levees stretch across the United States, most of them built of earth and covered with grass to protect the estimated 14 million people who live behind them, according to the National Committee on Levee Safety, which was set up by Congress in 2007.

But there is no single agency that regulates or monitors all of them, or even sets safety rules. Only about 14,800 miles of those are part of Corps programs, with the vast majority of the country’s levees falling under local or state control.

According to the National Committee on Levee Safety, there are no national policies or standards on levee safety, and there is no full assessment of their condition and performance. Only 10 states keep a list of their levees, and fewer than half have a state agency responsible for levee safety.

“We’ve adopted this piecemeal approach,” said Nicholas Pinter, a geology professor at the University of California, Davis. “We built these walls up to give the illusion of protection.”

Q: Why did so many fail?

A: From above, the lines of earthen levees that line the Missouri River in Mills County, Iowa, look like they have been decimated by a marauding army. Frigid, murky floodwater pours through huge, ragged gaps and spreads out for miles.

The county’s levees held during 2011 floods that inundated towns across the Midwest, but “this is different,” said Hurst.

Heavy rains from what meteorologists called a “bomb cyclone” storm that ripped across the plains fell onto frozen ground, and instead of soaking in, the rains and snowmelt poured into tiny creeks, tributaries and into the Missouri River.

Hurst said he watched the flow rate at one marker along the Missouri River soar from 16,000 cubic feet per second to 90,000. Water cascaded over the top of levees “like a waterfall,” he said, eroding the earthen banks and opening eight breaches.

Downriver, in northwest Missouri, volunteer crews and emergency workers were racing to build their own makeshift levees out of heaped dirt and sandbags in the hopes of pinning back the floodwaters. They did not hold.

Emergency officials said there were as many as 30 levee breaches in Atchison and Holt counties, and that the breaks brought walls of water rushing into tiny towns like Craig and Watson.

Q: Should they be rebuilt?

A: There are no easy answers along the rivers when it comes to balancing the interests of farmers, conservation groups and growing urban populations at a time when experts say that climate change is likely to lead to heavier rains and worse flooding.

While many communities will seek to rebuild their destroyed levees, conservation groups say the repairs only buy time before the next inevitable flood comes along, and that local and federal governments should more seriously consider relocating to higher ground and placing levees and development farther away from rivers and their flood plains.