NEW ORLEANS (AP) – The U.S. Army Corps of Engineers on Sunday opened the Bonnet Carre (BAH-nee KAR-ee) Spillway for the first time in nearly five years, diverting water into Lake Pontchartrain to decrease the flow of the swollen Mississippi River near New Orleans.

Heavy rain in the Mississippi Valley has put the river at its highest stages since 2011. The National Weather Service said the river was cresting Sunday at Tunica, Mississippi, and Helena, Arkansas.

Crest is predicted to happen Tuesday in Arkansas City, Arkansas; Wednesday in Greenville, Mississippi; Friday in Vicksburg, Mississippi; and Saturday in Natchez, Mississippi.

In Vicksburg and Natchez, low-lying areas have already started to flood, and local officials have said they’re making plans to help residents who need to move temporarily.

The Bonnet Carre Spillway, about 28 miles upriver from New Orleans, was built after the great river flood of 1927 as a flood-relief valve. It opens up more than a mile of the Mississippi’s east bank and pulls river waters into a 5.7-mile floodway that empties into Lake Pontchartrain and, eventually, the Gulf of Mexico.

The Corps opened the Bonnet Carre Spillway on Sunday morning to help keep the volume of Mississippi River flows at New Orleans from exceeding 1.25 million cubic feet per second – enough to fill the Superdome in a minute and 40 seconds.

NOLA.com/The Times-Picayune reports (http://bit.ly/1Zlu1vl ) that during a news conference Sunday, New Orleans Mayor Mitch Landrieu praises the spillway for keeping the city and nearby areas safe.

“What we’re witnessing right now is really an engineering miracle,” Landrieu said. “So many of us for so long wanted to make sure our homes and our lives were protected by creating a levee system. What you’re about to see is a levee system that is managed as a risk reduction (system), making sure we do what we’re supposed to do and when we’re supposed to do it, to protect lives and protect homes.”

The Bonnet Carre has been opened 10 times since 1931, most recently during the record floods of 2011.

The spillway may be open for several weeks. All public access areas within the spillway are closed beginning Sunday until further notice.

The Advocate reports (http://bit.ly/1K7uq8j ) that crowds gathered to watch the opening of the spillway in St. Charles Parish.

Anne Landry, 35, a fifth-grade teacher at Rudolph Matas Elementary in Metairie, took photos and video of the event for her class, which has been studying the source and tributaries of the river. Her friend Jennifer Lojszczyk, 38, who teaches at Catherine Strehle Elementary School in Avondale, tagged along for the educational experience but also for what she called “the wow factor.”