Mississippi falling, Corps closing spillway near New Orleans

NEW ORLEANS — The Mississippi River is falling at New Orleans and crews have begun closing a historic flood control structure that diverts the river’s water into a brackish lake, the Army Corps of Engineers said Tuesday.

The process could take about 10 days to two weeks if the weather remains good, Corps spokesman Matt Roe said.

At the river’s peak flow, 206 of the Bonnet Carre Spillway’s 350 bays were opened, pouring out 213,000 cubic feet (6,000 cubic meters) of water every second — enough to fill the Empire State Building in less than three minutes, or the Superdome in less than 10 minutes.

Each bay is opened and closed with 20 huge timbers called needles.

“We think we can close about 20 bays a day,” Roe said. “I think the goal would be 15 to 20 a day, depending on weather and other conditions.”

The spillway, a 1.5-mile-long (2.4-kilometer) structure parallel to the river, is opened to relieve stress on levees protecting New Orleans when the Mississippi is flowing at 1.25 million cubic feet (35,400 cubic meters) per second — fast enough to fill the Superdome in less than two minutes.

“Flows are dropping below that trigger point and the river is dropping to where they can safely get out there and drop the pins back in,” Roe said.

The water flows across nearly 8,000 acres (3,200 hectares) of land into Lake Pontchartrain.

The Feb. 28 opening was the 13th ever for the dam 28 miles (45 kilometers) above New Orleans. It was the first time the structure has been operated in consecutive years since it was completed in 1931.