As the Mississippi River rises, Corps practices Spillway opening

Fed by heavy rains in the Midwest, the Mississippi is rising and expected to crest April 8 at 16.5 feet at the Carrollton gauge in New Orleans, a half-foot below flood stage.

However, Corps officials say they don't expect to have to open the spillway.

Nevertheless, the possibility of more rain lent a little extra emphasis on the Army Corps of Engineers' annual drill to pull some of the wooden "needles" that seal off the spillway from the rising river.

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The spillway is the first to be opened when high water threatens thestructural integrity of the levees. It has been opened seven timessince it was built in 1931, the last in 1997. In more serious eventssuch as the 1973 flood, the Morganza Spillway and the West AtchafalayaFloodway can be opened to divert water away from communities inSoutheast Louisiana.

The levees at New Orleans are designed to hold back a river stage of20 feet at New Orleans with more than five feet of freeboard.

The Bonnet Carre Spillway consists of two basic components: a control structure along the east bank of the Mississippi River and a floodway that conveys the diverted flood waters to the lake. The control structure is a mechanically controlled concrete weir which extends for over a mile and a half parallel to the river. Confined by guide levees, the floodway stretches nearly six miles to Lake Pontchartrain.