Millions of Louisiana residents are facing a possible drinking water crisis as saltwater from the Gulf of Mexico threatens to contaminate the freshwater supply. The saltwater intrusion, caused by a severe summer drought that lowered the Mississippi River's water levels, could have serious consequences, as many local water treatment facilities are ill-equipped to handle high salt content, which can corrode pipes and pose health risks when consumed.

The U.S. Army Corps of Engineers is working to prevent an impending crisis in the southernmost stretch of the Mississippi River, but the situation remains critical.

"We're into preparedness and awareness. What we want to make sure is that everybody knows what we're facing," said Ricky Boyett of the Army Corps of Engineers. 

The issue at hand is the formation of a "saltwater wedge" caused by extremely dry conditions along the Mississippi River, leading to historically low freshwater levels and currents. This threatens the functionality of water treatment facilities situated along the river.

The saltwater intrusion has already advanced approximately 70 miles up the river from the Gulf of Mexico and is projected to reach Belle Chasse in southern New Orleans by mid-October. The saltwater density causes it to "crawl along the bottom" and continue to climb along the riverbed, Boyett said.

"The only thing that will fix the saltwater intrusion problem is rain," he said. "We need to get more water in the river."

In July, the Army Corps constructed an underwater sill, or levee, meant to block the saltwater flow. However, it was recently overtopped, prompting engineers to work on increasing its height by 25 feet. The solution, however, is not expected to hold back the saltwater for an extended period.

In New Orleans, demand for bottled water has surged, with some store shelves nearly empty. Further south, in Plaquemines Parish, drinking water advisories have been in place since June.

Efforts to address the problem could include transporting tens of millions of gallons of freshwater daily to nearby water treatment plants to dilute the salty water.

"There is not one thing that is going to solve this challenge for us. It's going to be a combination of lots of different efforts," said Louisiana Gov. John Bel Edwards. 

Local and state officials are also working on "just in case" solutions, such as connecting to other water supplies and bringing in millions of gallons of water to the plants via barges. The plans are being made because there is no major rain in the forecast for the upper parts of the Mississippi River.

But some, like Donald Link, a restaurant owner in New Orleans, aren't panicking. He said that after numerous devastating hurricanes, the BP oil spill and the COVID pandemic, people in Louisiana are used to adversity.

"It seems to me like we have time. So we start looking at sourcing if we need to buy bottled water. I'm hoping we never get to that point," Link said. 

Omar Villafranca

Omar Villafranca is a CBS News correspondent based in Dallas.

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