NEW ORLEANS -- A small army of engineers, deputies and even prison inmates is at work along the surging Mississippi River. They're keeping watch around-the-clock on the floodwalls and earthen levees holding back the water.

The levee-watchers are looking for any droplets that seep through the barriers, and any cracks that could turn small leaks into big problems.

Officials have made a series of high-stakes decisions aimed at protecting homes and businesses that sit behind the levees and floodwalls. They opened a spillway, choosing to flood rural areas with fewer homes in hopes of sparing Baton Rouge and New Orleans. They've also closed the Mississippi River at the port in Natchez, Miss., out of concern that barges could increase pressure on the levees. There were also fears that barges couldn't operate safely in the flooded river.

Port officials said the interruption could cost the U.S. economy hundreds of millions of dollars per day.

The river is already 3 feet higher at Natchez than a record set in 1937, and it's not expected to crest until Saturday.