DUTCHTOWN, Mo. — Floodwaters leaking past an old earthen levee in this river town highlight a larger problem threatening much of rural America: Scores of flood walls built decades ago by farmers are increasingly susceptible to failure.

Many of the barriers are little more than piles of compacted dirt that were constructed without help from engineers, mainly to protect crops. Now they shield entire communities, and they are managed by local authorities who have little to no money for repairs.

"You build them to the levels that you hope are adequate," said Jeff Rolland, deputy police chief in Poplar Bluff, a southeast Missouri town of 17,000 people protected by just such a levee. "Unfortunately, extraordinary storms come along."

That's what happened this week after as much as 15 inches of rain fell on the region in four days, causing the Black River to climb out of its banks. The flood displaced more than 1,000 people and sent water over the Poplar Bluff levee.

The levee is one of more than 100 across the country considered by the federal government to be unfit for use. The failing levees are in 16 states, including five in Ohio, five in Louisiana and 16 in Washington. As still more rain fell Wednesday, all eyes were on the flood walls and the rising water.

The Reorganized Butler County No. 7 levee at Poplar Bluff failed a federal inspection in 2008. And the heavy rain took a swift toll, allowing water to seep through the levee, pour over the top in 35 places and gush through a hole in the middle of the barrier.

Many rural levees are privately maintained and overseen by local boards or commissions with limited expertise and resources. Even if the officials who oversee the Poplar Bluff levee had the money to fix it, the poor government rating makes them ineligible for federal assistance.

"It was dropped from the program," said Tony Hill, chief of the emergency management office for the Army Corps of Engineers office in Little Rock, Ark. "They were given a period of time, given a year to get things right. They are inactive in the program. They aren't eligible for federal dollars to fix the levee."

The quality of small-town levees varies greatly. Most are made of mounded dirt that has been sloped and then topped with grass to reduce erosion.

Others are more complex, with spillways, drainage systems and pumps. But for cities and private levee districts that are strapped for cash, levees are often little more than earthen berms, like the one at Poplar Bluff, about 130 miles south of St. Louis.

"People don't realize the levee is there until the water starts rising," said Tom Waters, chairman of the Missouri Levee and Drainage District Association. "The local districts do what they can, but sometimes it's cheaper to be out of compliance and fix it yourself than be in compliance."

A 2009 Army Corps survey identified 114 levees nationwide that were "unacceptable for operations and maintenance," including three others in Butler County, 30 in Arkansas and 27 in California. The survey lists structure from Alamosa, Colo., on the Rio Grande, to the Bethlehem levee in the Pennsylvania town of the same name.

Two years earlier, the federal agency found 122 levees in similar condition.

After Hurricane Katrina, Congress in 2006 gave money to the Army Corps to update its inventory of the federally maintained levees, which make up 14,000 miles of flood barrier across the nation.

But there's no systematic oversight — or even a complete inventory — of the nearly 100,000 miles' worth of private levees. Congress passed the National Levee Safety Act in 2007 and directed the Army engineers to account for all private levees, but no money was provided for the task.

"You can't really generate any interest until right after a disaster," said Stephen Verigin, a civil engineer in Sacramento, Calif., and member of the National Committee on Levee Safety. "If you don't have an immediate failure in the recent past, it's very difficult to get support."

The levee safety committee made 20 specific recommendations, including creation of a National Levee Safety Commission that would help create and enforce uniform engineering standards and work with states to bolster local efforts. So far, no one has acted on those suggestions.

On Wednesday, Poplar Bluff and other southern Missouri towns endured more rain and the threat of tornadoes from the second severe storm system in as many days.

The good news, according to National Weather Service hydrologist Mary Lamm, was that Thursday and Friday should be dry, and the rivers should begin to recede.

But that doesn't mean towns like Poplar Bluff are entirely out of peril.

"It's still going to be a lot of strain on a lot of the levees, even when we got that final rain out of here," Lamm said from Paducah, Ky.

Butler County Sheriff Mark Dobbs said it was too early to know how many homes and businesses had been damaged. "The water's just getting deeper," he said. "It was already bad. It's just getting worse."

Authorities have conducted at least 120 rescues from homes and stranded vehicles over the past two days. More than 250 people were staying at a Red Cross shelter at the town's 500-seat concert venue, along with more than 110 pets.

Several other towns along the Mississippi asked for help filling sandbags as river levels continued to rise to potentially record heights.

Volunteers in Dutchtown, Mo., about 100 miles south of St. Louis, erected a makeshift levee consisting of 7,000 tons of gravel fashioned into a 6-foot wall topped with plastic and sandbags.

In Kentucky, emergency crews spent a third day rescuing residents stranded by the rising Ohio River near Paducah. More than 20 families have been ferried from their homes in boats.

Missouri Gov. Jay Nixon, who toured the flood damage Tuesday in Poplar Bluff, suggested that the state may need to step up its oversight of rural levees. But for now, he said, public safety and the rebuilding effort takes priority.

"Once we get through all of this, we'll have an evaluation of where they're weakened, where they're broken, but our focus now is on getting people safe."

Rural areas aren't the only places wrestling with flood protection. In Dallas, city leaders have spent the past two decades struggling to agree on plans to strengthen two earthen levees on the Trinity River that broke in 1990.

The levee-improvement plan grew to include a $1 billion toll road, new city parks and more.

"I can't tell you what happened," said former Mayor Steve Bartlett, now an executive with a Washington, D.C., trade association. "We recognized the severity of disaster should we have severe flooding."

Scher Zagier reported from Columbia, Mo. Associated Press Writer Heather Hollingsworth in Kansas City, Mo., contributed to this report.