NORCO, La. (AP) — 10:45 a.m.
Workers have begun opening an 87-year-old flood control structure to divert water from the rising Mississippi River away from New Orleans.
It's the 12th time the Bonnet Carre spillway has been opened since it was completed in 1931.
The U.S. Army Corps of Engineers is opening a section of the structure to divert some of the swift-moving waters north into Lake Pontchartrain and, eventually, into the Gulf of Mexico.
The move prevents a potential strain on New Orleans levees. But it also raises environmental concerns. The river water affects the salinity of coastal waters — affecting fisheries. And it carries nutrients that can cause harmful algae blooms.
When an 87-year-old flood control structure is opened northwest of New Orleans, it will lower the flood threat for that city, while raising environmental concerns.
The U.S. Army Corps of Engineers will open part of the Bonnet Carre Spillway on Thursday. That will divert some of the rising Mississippi River's waters north into Lake Pontchartrain and, eventually, into the Gulf of Mexico.
It will keep the powerful current of the rising river from putting a strain on New Orleans levees. But it also affects the salinity in the huge lake and in the Mississippi Sound, which can mean trouble for oyster harvests off the Louisiana and Mississippi Gulf Coasts. The river also carries nutrients that can cause algae blooms in the lake, which can lead to fish kills.