Mississippi River floodgate to open at 3 p.m. CDT

MORGANZA, La. — Engineers made final preparations Saturday afternoon to slowly open a 10-ton, steel emergency floodgate for the first time in nearly four decades, purposefully inundating farmlands and homes in Louisiana's Cajun country to drain the swelling Mississippi River.

Across the countryside, people fled to higher ground, shored up levees that held the last time the Morganza spillway was opened and built new walls of sand and dirt to hold back the flood they have known was coming for weeks.

AP Photo/Rogelio V. Solis

A crew of workmen carry drainage hose along a temporary seawall adjacent to the Ameristar Casino in Vicksburg, Miss., as Mississippi River floodwaters creep up the flood walls Saturday.

"We're using every flood control tool we have in the system," Army Corps of Engineers Maj. Gen. Michael Walsh said Saturday from the dry side of the spillway, which was expected to be under several feet of water Sunday.

It will take about 15 minutes for one of the 28-feet gates to be raised, then several hours before any of the water hits sparsely populated communities. The corps plans to open one or two more gates Sunday in a painstaking process that gives residents and animals a chance to get out of the way.

About 25,000 people and 11,000 structures could be in harm's way when the Morganza spillway is unlocked for the first time since 1973, but diverting the river water will help take the pressure off levees downstream. Easing the strain on the river walls helps make sure the river doesn't flood more populated cities like Baton Rouge and New Orleans, and the numerous oil refineries and chemical plants along the lower reaches of the Mississippi.

AP Photo/Rogelio V. Solis

A Mississippi River tow boat powers up the Mississippi River through the high floodwaters near Vicksburg, Miss. Friday. The water level is not expected to crest in Vicksburg until Thursday.

In Krotz Springs, La., one of the towns in the Atchafalaya River basin bracing for floodwaters, Monita Reed, 56, recalled the last time the Morganza was opened in 1973.

"We could sit in our yard and hear the water," she said as workers constructed a makeshift levee of sandbags and soil-filled mesh boxes in hopes of protecting the 240 homes in her subdivision.

Some people living in the threatened stretch of countryside — an area known for small farms, fish camps and a drawling French dialect — have already started heading out. Reed's family packed her furniture, clothing and pictures in a rental truck and a relative's trailer.

"I'm just going to move and store my stuff. I'm going to stay here until they tell us to leave," Reed said. "Hopefully, we won't see much water and then I can move back in. "

Opening the spillway will release water that could submerge about 3,000 square miles, some places would be under as much as 25 feet in some areas.

"Protecting lives is the No. 1 priority," Army Corps of Engineers Maj. Gen. Michael Walsh said Friday at a news conference aboard a vessel on the river at Vicksburg. A few hours later, the corps made the decision to open the key spillway.

Engineers feared that weeks of pressure on the levees could cause them to fail, swamping New Orleans under as much as 20 feet of water in a disaster that would have been much worse than Hurricane Katrina in 2005.

Instead, the water will flow 20 miles south into the Atchafalaya Basin. From there it will roll on to Morgan City, an oil-and-seafood hub and a community of 12,000, and eventually into the Gulf of Mexico.

The Krotz Springs area was in a sliver of land about 70 miles long and 20 miles wide, north of Morgan City. The finger-shaped strip of land was expected to be inundated with 10- to 20-feet of water, according to Army Corps of Engineers estimates.

It will take days for the water to run south, and it wasn't expected to reach Morgan City until around Tuesday.

The corps employed a similar cities-first strategy earlier this month when it blew up a levee in Missouri — inundating an estimated 200 square miles of farmland and damaging or destroying about 100 homes — to take the pressure off the levees protecting the town of Cairo, Ill., population 2,800.

The disaster was averted in Cairo, a bottleneck where the Ohio and Mississippi rivers meet.