As drought lowers fresh water levels on the Mississippi River, a flood of salt water is slowly traveling up from the Gulf of Mexico to take its place, threatening the city of New Orleans’s water supply.

Thousands of people living in Plaquemines Parish have already had their water supply contaminated by ocean water this summer, and officials expect that New Orleans, which draws much of its water supply from the river, will be forced to contend with saltwater creating unsafe drinking conditions, corroded pipes and destroyed appliances over the next few weeks.

President Biden declared a state of emergency in the region on Wednesday, while the state of Louisiana and the Army Corps of Engineers are attempting various techniques to improve conditions, including osmosis machines to desalinate the water, a massive pipeline to bring drinking water south from upstream, and underwater levees to keep the saltwater at bay.

But this confluence of sea level rise and climate-charged drought, officials say, is much broader than one solution can tackle.

“This is not typical,” Robert Miller, a coastal hydrologist and professor at the University of Louisiana at Lafayette, told CNN. “When you have a back-to-back situation, the salinity will keep creeping in. It’s a buildup, it’s a cumulative effect.”

(CNNNew York Times $, AxiosWDSUWSJ $, CNBC)