Gerald Herbert / AP

This flood wall and floodgate are along Lakeshore Drive and Lake Pontchartrain in New Orleans, La.

In the busy and under-staffed offices of New Orleans' flood-control leaders, there's an uneasy feeling about what lies ahead.

By the time the next hurricane season starts in June of 2013, the city will take control of much of a revamped protection system of gates, walls and armored levees that the Army Corps of Engineers has spent about $12 billion building. The corps has about $1 billion worth of work left. 

Engineers consider it a Rolls Royce of flood protection — comparable to systems in seaside European cities such as St. Petersburg, Venice, Rotterdam and Amsterdam. Whether the infrastructure can hold is less in question than whether New Orleans can be trusted with the keys. 

The Army Corps estimates it will take $38 million a year to pay for upkeep, maintenance and operational costs after it's turned over to local officials. 

Local flood-control chief Robert Turner said he has questions about where that money will come from. At current funding levels, the region will run out of money to properly operate the high-powered system within a decade unless a new revenue source is found. 

"There's a price to pay for resiliency," the levee engineer said from his office at the Southeast Louisiana Flood Protection Authority-East. "We can't let pieces of this system die away. We can't be parochial about it." 

On Nov. 6, New Orleans voters were faced with one of their first challenges on flood protection when they voted on renewal of a critical levee tax. The tax levy was approved, meaning millions of dollars should be available annually for levee maintenance. 

Bob Bea, a civil engineer at the University of California, said the region must find additional money to keep the system working properly. "If you try to operate it and maintain it on a shoestring, then it won't provide the protection that people deserve." 

Many locals remain uneasy, even though Turner's agency is a welcome replacement for local levee boards that were previously derided. 

"It's scary," said C. Ray Bergeron, owner of Fleur De Lis Car Care, a service station in the Lakeview neighborhood where water rose to rooftops after levees collapsed during Hurricane Katrina in August 2005. Before Katrina, Bergeron said the local levee boards were complacent. "They told everybody everything was fine, 'Oh yeah, it's fine. Let's go have martinis and lunch.'" 

After Katrina, the locally run levee boards that oversaw the area's defenses were vilified, and quickly replaced by the regional levee district run by Turner. 

Congressional investigations found the old Orleans Levee Board more interested in managing a casino license and two marinas than looking after levees. Inspections were ceremonial, millions of dollars were spent on a fountain and overpasses rather than on levee protection. And there was confusion over who was responsible for managing the fragmented levee system, U.S. Senate investigations revealed. 

Still, experts generally agree the old levee board's failings did not cause the levees to collapse during Katrina. Poor levee designs by the corps and the sheer strength of Katrina get the lion's share of the blame. 

Since the Flood Control Act of 1936, the Army Corps has given local or state authorities oversight of water-control projects, whether earthen levees in the Midwest or beach walls in New England. 

Bill Haber / AP

Water is pumped through giant tubes around the floodgate at the London Ave. outflow canal during a test in New Orleans in May 2009.

"That's been the eternal problem with flood-protection systems," said Thomas Wolff, an engineer at Michigan State University. "You build something very good and then give it to local interests who are not as well-funded." 

New Orleans is an unusual case because the area is inheriting the nation's first-of-its-kind urban flood control system. 

"We've given a very expensive system to a place that may not be able to afford it over the long term," said Leonard Shabman, an Arlington, Va.-based water resources expert. Letting the Army Corps run it isn't much of a solution either, he added. "It's not like the corps' budget is flush." 

The nation has spent lavishly on fixing the system in the seven years since Katrina flooded 80 percent of New Orleans and left 1,800 people dead. 

"It is better than what the Dutch have for the types of storms we have," said Carlton Dufrechou, a member of the board of the Lake Pontchartrain Basin Foundation, which monitors local environmental issues. 

Ensuring it remains that way could be tricky. The biggest headaches are several mega-projects with lots of moving parts, all needing constant upkeep. The corps is building them across major waterways that lead into New Orleans. 

Take for instance the 1.8-mile-long, 26-foot-high surge barrier southeast of the French Quarter that blocks water coming up from the Gulf of Mexico across lakes and into the city's canals. Water from this direction doomed the Lower 9th Ward and threatened to flood the French Quarter. Maintaining this giant wall alone will cost $4 million or more a year. 

"You have to get out there and do exercises, do the preventive maintenance, change out equipment over time on a particular schedule," Turner said, enumerating the challenges. "There are a lot of cases where a single thing goes wrong and that can create a failure, a complete failure where you can't close the system." 

There is a mounting list of to-dos. 

Already, lightning has knocked out chunks of wall. Grass hasn't grown well on several new stretches of levee. Louisiana State University grass experts have been called in to help seed them. 

There are recurring problems with vibrations and shuddering on a new floodgate at Bayou Dupre in St. Bernard Parish. The corps has plans to overhaul the structure in the spring before handing it over to local control. And there will be the inevitable sinking of levees and structures, as always happens in south Louisiana's naturally soft soils. Over time, levees will have to be raised. 

Col. Ed Fleming, the New Orleans corps commander, said his outfit will work to ensure the transition to local control is smooth. 

"This happens with corps civil projects all over the country. That's the way it works in Iraq, Afghanistan," he said. "We have authority to build, but we have no authority to do operations and maintenance." 

More content from NBCNews.com:

• Woman denies murder to avenge husband's death
• Columbine survivor turns to Occupy LA to battle foreclosure
• 'They didn't seem afraid': Wild coyotes pay visit to Chicago's Wrigley Field
• Top 10 fugitive went to extremes to evade capture in Mexico
• Powerball jackpot to hit at least $425 million on Wednesday
• Autopsy: Cockroach-eating contest winner choked to death
• Video: UPS ‘boot camp’ preps workers for the holidays

Follow US news from NBCNews.com on Twitter and Facebook