As saltwater flows up the Mississippi River for a third year, the region looks for permanent solutions
Just off the Mississippi River in southeast Louisiana, an 18-wheeler trailer filled with white cylinders whirred as workers prepared to turn the machine off for the day. The truck houses a reverse osmosis system, and it’s stopping salt water from contaminating drinking water for more than 20,000 people.
This is the third year in a row that salt water from the Gulf of Mexico has crept up the Mississippi River. This phenomenon, known as saltwater intrusion, occurs when the rate of flow in the river dips below 300,000 cubic feet per second, leaving the river’s fresh water unable to push back against salt water at its mouth. Previously, this only happened about once per decade.
For cities within 100 miles of the river’s southern terminus—most of whom depend on the river’s fresh water for their drinking water—saltwater intrusion is an existential threat. Last year, the saltwater wedge almost reached as far as New Orleans, 80 miles upriver, causing panic until rains pushed it downriver.
But it did reach Plaquemines Parish, which surrounds the last 70 miles of the Mississippi.
