Officials with the Army Corps of Engineers are disputing data in a Corps database that shows numerous sections of Mississippi River levees in New Orleans and points downriver fall short of the 20-foot height at which forecasters expect the river to crest Saturday.

Ricky Boyett, a Corps spokesman, said late Wednesday that the Corps’ New Orleans District office shows levee elevations in the Lower 9th Ward at “between 20 and 21 feet.” He added that the agency’s modeling “does not show overtopping of the levees in the 9th (Ward).”

The Times-Picayune | New Orleans Advocate reported earlier Wednesday that a Corps database, housed on the Corps’ website, showed levees are below 20 feet in numerous locations, including spots in Bywater, the Lower 9th Ward and Algiers, as well as much of St. Bernard Parish. The database shows levee heights of between 18 and 20 feet in those locations.

The newspaper used that data after being told by the Corps on Wednesday that the information in the database was reliable and up-to-date.

Corps officials have not explained the disconnect between Boyett's remarks and the information on the website.

John Monson, regional director of the Southeast Louisiana Flood Protection Authority-West, said on Thursday that he had gone out to survey levees in Algiers after becoming concerned about some of the heights listed in the Corps' database. His personal surveys showed the levees to be 25 feet high, putting them well above the projected river levels, he said.

The question over actual levee heights could become moot: The National Weather Service on Thursday morning updated its forecast for the river, predicting the river will rise to a crest of 19 feet, a foot lower than earlier forecasts.

If the storm surge from the system — which became Tropical Storm Barry on Thursday and is still expected to become Hurricane Barry — does overtop the river levees in New Orleans, it would be the first such occurrence in the city’s modern history.

While Boyett said Corps officials don’t expect overtopping in the city at this point, he acknowledged there are some weak spots in the area’s defenses.

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At one such low spot, the Harvey Canal Lock on the West Bank, officials were installing "stoplogs" to add about 3 feet to its height to reduce the chances that it will be overtopped.

And Boyett said officials are aware of one levee segment in St. Bernard near the Violet Canal "that we are evaluating and may need to flood fight if this forecasted surge holds."

Officials in St. Bernard Parish declined to issue evacuation orders for Barry because they said officials from the National Weather Service and U.S. Army Corps of Engineers had assured them that the storm surge wouldn't pose a major threat to the parish's levee system.

But at a news conference Thursday morning, St. Bernard President Guy McInnis warned families to be prepared, noting that low-lying areas in the eastern part of parish, outside of the levee protection system, were expected to get 3 to 5 feet in storm surge.

In what could be more reason for optimism, Boyett also said there's a good chance that the way the water in the river is measured, compared to the height of levees, could provide nearly a foot more of additional protection than forecasters had been counting on.

That’s because the river gauge on which the water levels are measured uses a 1929 datum measurement to determine its height, while the corps uses a 1988 datum for levees, resulting in the height difference, he said.

Even if some levees are overtopped, Boyett stressed Corps officials think there is little risk of levee failures.

“We’re confident with the integrity. The levees are extremely robust and designed to handle a lot of pressure,” Boyett said.

If the river does rise as high as 20 feet in New Orleans, Boyett said, Corps officials think the surge will definitely overtop river levees south of Oakville and Caernarvon in Plaquemines Parish, allowing some water to flow into protected areas. There also could be intermittent overtopping of levees farther upriver because of wave action in the river, though that would not create the constant flow expected at low areas downriver, he said.

Staff writers Jeff Adelson and Della Hasselle contributed to this story.