What Is Saltwater Intrusion? Gulf Of Mexico Invading Louisiana’s Drinking Water As Drought Drains Mississippi River

Southeast Louisianans who primarily get their drinking water from the Mississippi River could be affected by intrusion from the Gulf of Mexico, which is when salt water progresses farther upriver than usual, bringing increased salinity to groundwater and drinking water systems, according to the Environmental Protection Agency.

Intrusion is often sparked by rising sea levels or drought: Nearly 80% of the Midwest is abnormally dry as of this week and 50% is currently in a moderate drought, according to the U.S. Drought Monitor, and the lack of rain in this area has weakened the Mississippi River’s ability to fight off salt water pushing in from the Gulf of Mexico, experts say.

Ricky Boyett of the U.S. Army Corps of Engineers (USACE) told Forbes that more rain in areas like Illinois, Missouri and Ohio is needed for the Mississippi River to build up its flow and push the salt water from the gulf out.

According to Boyett, the river needs at least 300,000 cubic feet per second of water flowing down it to keep out the salt from the Gulf of Mexico; right now, he says, there’s only about half of that coming down the river.

Up to 885,030 residents across four parishes, or counties—including New Orleans—could be impacted by saltwater intrusion in the coming months, hitting nearly 20% of Louisiana’s population, Gov. John Bel Edwards (D-La.) said in a letter to President Joe Biden requesting an emergency declaration.

Local officials in Orleans Parish (where New Orleans is), Jefferson Parish, Plaquemines Parish and St. Bernard Parish have declared emergencies for their communities and made efforts to purchase bottled water and request reverse osmosis systems—which remove water contaminants—for their water facilities.