Louisiana watches a rising Mississippi

To save New Orleans, levees south of the city were dynamited, relieving pressure upriver but flooding St. Bernard and Plaquemines parishes. So bitter and lasting is the memory of that act that accusations surfaced of levee dynamiting during Hurricane Betsy in 1965 and Hurricane Katrina in 2005. Officials have strongly denied levees were deliberately blasted during the storms.

One of the legacies of the 1927 flood is the Bonnet Carre Spillway.

The 7,000-foot-long spillway about 40 miles north of New Orleans was one of the first major structures built after the flood. Constructed between 1929 and 1931, it is a release valve for the river before it can threaten New Orleans.

The structure was last opened in 1997, sending the river's filthy fertilizer-and-urban-runoff rich water into Lake Pontchartrain, north of New Orleans.

Environmentalists fear opening Bonnet Carre this spring would sully the lake's natural environment. Seafood harvesting also could be affected as the torrent of fresh water pours first into brackish Lake Pontchartrain and then into the salty Gulf of Mexico.

Corps workers spent Tuesday testing the spillway structure for a possible opening by lifting some of the wooden beams, or "needles," to allow water to flow freely through.

"We want to be prepared," said Christopher Brantley, the spillway's project manager. "The Mississippi changes — if not daily, on a weekly basis."

Water has been pouring through the structure's fence-like series of 7,000 beams for several days, slowly pooling in the 7 miles of forest and grass that make up the spillway between the river and Lake Pontchartrain. Water is expected to continue flowing through gaps in beams for many more days.

New Orleans levees not thought to be at risk
The flow already has interrupted corps' workers extracting valuable clay from borrow pits in the spillway. The clay was being trucked to New Orleans to build up hurricane protection levees. River levees in the city are not believed to be at risk.

"By the weekend, the water should be from levee to levee; all of this grassy area will be covered," Brantley said, standing in the foreground of the structure. The spillway is bounded by levees.

The locals aren't panicking. In fact, many are looking forward to a spillway brimming with water.

"In 1997, they opened it and everybody was out here crawfishing, mud-riding, acting like a bunch of kids, playing in the mud," said Christy Rodrigue as she watched the water rise in the with her husband, Billy, a pipe-fitter.

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