As it barreled into southern Louisiana as a Category 4 storm on Sunday, Hurricane Ida drew comparisons to 2005's Hurricane Katrina, which ravaged New Orleans and overwhelmed its aging levee system exactly 16 years earlier. Ida knocked out power to New Orleans and caused other damage, but the levees, flood walls, and floodgates held and protected the city from the storm surge. 

All across Louisiana, "we don't believe there is a single levee anywhere now that actually breached or failed," Gov. John Bel Edwards (D) said Monday. "There were a few smaller levees that were overtopped to a degree for a certain period of time," but the lack of any breaches or failures is "good news." Ricky Boyett, a spokesman for the U.S. Army Corps of Engineers, said the flood protection system "did what it's supposed to do" and "performed as designed." 

The Army Corps of Engineers oversaw a $14.5 billion effort to rebuild and improve the New Orleans levees and build out protections for the surrounding suburbs south of Lake Pontchartrain, starting with a 130-mile ring to block storm surges of up to 30 feet, The Associated Press reports. Half of New Orleans is below sea level. 

"We have a good system now and I'm pretty confident it worked," Sandy Rosenthal, founder of Levees.org, tells The Washington Post. "We found out what didn't work at horrific human cost. This system is better, stronger, and bigger." But the city is still vulnerable to a hurricane that stalled and dumped large amounts of rain on New Orleans — like Hurricane Harvey in Houston — and the New Orleans system didn't protect other suburbs like LaPlace, whose own levee project isn't scheduled for completion until 2024.

And about 62 percent of Americans who live in communities protected by more than 2,300 miles of levees from California to Florida have seen no overhaul of their flood protection systems in recent years, the Post reports. And maintaining the New Orleans flood protections isn't cheap — it costs about $1 billion a year, Rosenthal says.

Hurricane Katrina left 1,500 people dead in New Orleans. So far, only two confirmed deaths have been tied to Hurricane Ida in all of Louisiana, though that number will almost certainly rise.