Five flood-control levees around the Washington area -- two in Prince George's County and three in the District -- have "unacceptable" maintenance problems that could reduce their ability to hold back water during a major storm, according to new information released by the U.S. Army Corps of Engineers.

The problems were identified after national levee inspection standards were tightened in the aftermath of Hurricane Katrina, a corps official said. More than 120 levees across the country were found to need urgent repair.

Two of the levees are along the Anacostia River in Prince George's. The three in the District include one decades-old berm on the Mall that was designed to keep the Tidal Basin from overflowing into downtown streets.

In all five cases, local officials downplayed the danger, saying that the problems were mostly minor -- such as tree roots intruding into earthen levees -- and easy to fix. But an official at the Army Corps of Engineers said that any weakened levee should be a concern.

"These projects are at higher risk than projects that are properly maintained," said Tony Vidal, chief of the Civil Works Branch at the Corps of Engineers office in Baltimore. "What that risk is, is hard to say."

The Washington area's system of levees can be easy to overlook, because some of the earthworks are in off-limits areas of the shoreline or blend into the landscaping of riverside parks. In some cases -- such as the Mall's berm, concealed behind elm trees on the north side of the Reflecting Pool -- it has been years since the levees were tested seriously by a storm.

Now, Hurricane Katrina has made them a focus of government attention.

In the aftermath of that 2005 storm, in which New Orleans's extensive levee system failed to keep floodwaters out of the city, the Corps of Engineers changed the way it evaluates levees nationwide, Vidal said. Levees that had previously passed inspections were now deemed to need immediate attention, sometimes because of problems that had been there for years.

In the local cases, Vidal said, the agencies in charge of the levees will have one year to bring the levees up to the new standards. If the problems are not fixed, the "unacceptable" ratings could require some neighboring residents and building owners to buy flood insurance for the first time, he said.

In Prince George's, the Corps of Engineers found problems with levees alongside the Anacostia River in the Bladensburg and Hyattsville areas. Trees were the main problem, dozens of them, growing on and near the levees.

That's a problem, experts say, because the trees could blow over and rip out chunks of the mostly earthen flood barriers.

Perhaps 100 or more trees will have to be cut down in the spring, said Susan Hubbard, a spokeswoman for the county Department of Public Works and Transportation.

Two of the three District levees cited in the report also are on the Anacostia.

One runs along the shoreline of the riverside military complex in Southwest Washington, home to Bolling Air Force Base and the Navy's Anacostia Annex. Near the naval facility, Corps of Engineers officials noted trees growing into the sides of the levees.

At the same site, inspectors found that storm-water drainpipes could pose a problem during a flood, if water from the river were to flow through them backward to the other side of the levee. They ordered that gates be added, so water could flow only in one direction.

A spokesman for Naval District Washington, which maintains the levee, said that all needed repairs at the site would be minor and could be finished by October. "There is no imminent danger of the levee failing," William L.A. Anderson, a spokesman for the naval district, wrote in an e-mail message.

Another of the District's problem levees is on National Park Service land near the east end of the Frederick Douglass Memorial Bridge. There, trees on the levee were also cited as a problem -- as was the lack of a gate that could seal a gap in the levee during storms, a Park Service spokesman said.

Spokesman Bill Line said that the Park Service was working to fix the problems at this site, but that the potential danger to surrounding neighborhoods was minimal. He said that there had been flooding in that area before, during Hurricane Isabel in 2003, but only Park Service administration buildings were affected.

"There is a risk of flooding. But I would say in the area that's to be flooded, there's no homes," Line said.

The District's third flood-control problem is on the Mall. The elm trees along the Reflecting Pool might extend their roots under the levee, potentially undermining it, an inspection found. Another problem is where the levee ends: It stops before 17th Street, potentially leaving the street as a channel for floodwaters during a storm.

Line said that, for now, there were no plans to cut down the elm trees. As for 17th Street, authorities were still looking for the best way to block it in a storm, he said.