Louisiana officials are being forced to make some difficult decisions.
The raging Mississippi River is putting intense pressure on downstream levees that protect New Orleans and the oil refineries along the river's lower reaches.
To relieve the burden, army engineers will open the Morganza spillway for the first time in 38 years.
Experts say this could result in tens of thousands of homes and farms across Louisiana's Cajun country under as much as eight metres of water. Up to 77 hundred square kilometres of land could be affected by the flooding.
According to officials, they have to put the rural areas under water in order to alleviate water flows.
Engineers worry that weeks of pressure buildup on the downstream levees could cause them to fail, swamping New Orleans under as much as seven metres of water.
The potential flooding could be worse than the Hurricane Katrina disaster in 2005.
Around 25,000 of the area's residents are aware of the situation. Shelters have recently opened to house those affected by the rising waters.
With files from The Associated Press