The Army Corps of Engineers has known for decades that its continual efforts to deepen the Mississippi River for bigger ships would eventually trigger the saltwater crisis that has now gripped the New Orleans area for weeks.
“This is certainly something that everybody knew was going to happen,” said Cecil Soileau, a retired Corps engineer who warned in a 1990 report that dredging the lower river would threaten the region’s drinking water.
That report, written with two other Corps engineers, said “a substantial body of historical evidence pointed to channel deepening as the major cause of increases in frequency and duration of saltwater intrusion events.”
While drought in the Midwest has drastically cut downriver flows this year, dredging to make way for larger cargo ships was the key to bringing the Gulf of Mexico’s salty water to New Orleans’ doorstep, said Soileau, who was chief of the hydrology and hydraulics branch of the Corps’ New Orleans division before he retired in 1993.
“We have droughts every 20 or 30 years,” he said. “We had them in 1930s, 1953, 1988. But it didn’t seem to bother us before Southwest Pass was deepened. Now it takes a lot more fresh water to keep the salt water from coming in.”
Had the lower river not been deepened to 55 feet in recent years, the salt water likely would have halted near Alliance, about 20 miles downriver from New Orleans, Soileau said.
The Corps has repeatedly acknowledged that channel deepening exacerbates saltwater intrusion, but agency officials have stressed in recent weeks that the current crisis is more an act of God than man.
“Saltwater intrusion in the Mississippi River during extreme low water has been a naturally occurring phenomenon since before the deepening of the river,” Corps spokesperson Ricky Boyett said.