It didn’t take long for the water to rush in.

In fact, just a few minutes after noon, media and officials had to move up the levee to avoid a rising tide. According to the Army Corps of Engineers, the spillway opening went off without a hitch.

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Bonnet Carre Spillway

The Corps pulled the pins promptly at noon, opening the Bonnet Carre Spillway for the first time since 1997.

The spillway diverts water from the rising Mississippi River six miles north to Lake Pontchartrain. The goal is to take pressure off the levees downriver and spare the greater New Orleans area from possible flooding as the river nears flood stage in the city.

“It's a preventive measure to reduce any chances for flooding from overtopping or additional scour that can cause potentially any issues,” Lt. Col. Murray Starkel said.

The Corps opened 38 of the 350 bays along the mile and a half long structure near Norco. Crews are expected to open more over the next few days. The corps is expected to keep the spillway open for at least two weeks.

“The idea is we will open it only as long as we need to open it and only when it absolutely needs to be open because we understand the impacts to the estuary and environment, the salinity regime in Lake Pontchartrain and the surrounding bodies of water,” Starkel said.

Environmentalists said fishing is expected to take a hit because of the rush of fresh water into the normally brackish lake. There also is the possibility of an algal bloom, which can cause fish kills in Lake Pontchartrain and other local waterways.

"I think we should say that it's highly possible, yes,” Corps Environmental Officer Beth Wiggins said. “There's no question that the river brings in a lot of nutrients and when you get into the summer months, with the heat, we have seen them in the past.”

The Pontchartrain Levee District is also watching the rising tide on the lake. It is expected to rise as much as six inches because of the spillway opening. The levee board president said if it gets much higher than that it could threaten levee building along the lake in St. Charles Parish.

“My concern would be not the flood structures themselves, but if the earthen levee that's under construction suffered some sort of a washout,” said Steve Wilson, a Pontchartrain Levee District spokesman.

The Coast Guard issued a notice to mariners to beware of hazards on the river near the spillway.

The Corps said the lake level should not cause any problems as far as the outfall canals in the city are concerned. But crews are monitoring the situation around the clock and if they need to close off the canals, they are ready to spring into action.