AILSA CHANG, HOST:
The state of Louisiana has asked for a federal emergency because of saltwater that is moving up the Mississippi River. The slow-moving, salty water has already seeped into drinking supplies in southern Louisiana, and it's moving up towards New Orleans. Halle Parker with member station WWNO joins us now. Hi, Halle.
HALLE PARKER, BYLINE: Hi.
CHANG: OK. So I've heard this called a saltwater wedge. What does that mean, and why is this happening?
PARKER: Yes. OK, so saltwater wedge 101 - right now we're in a historic drought all throughout the Mississippi River watershed, right? So there's way less water flowing down the river than usual. And, you know, when that happens, saltwater from the Gulf of Mexico can migrate upriver along the river's bottom, which is actually below sea level.
CHANG: Has this happened before?
PARKER: Yeah. So this is actually cyclical. It tends to happen once a decade down here, but usually it doesn't extend as far north as New Orleans, nor does it happen in back-to-back years like it is right now. The last time the saltwater made it up this far up the river was in 1988, and it only stuck around for a few days. But officials here like Governor John Bel Edwards have warned this time it's different.
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JOHN BEL EDWARDS: Based on the current forecast, this event will be more severe and of longer duration. But there is no need for panic.
CHANG: No need for panic. OK. Well, how are residents actually reacting right now?
PARKER: Well, as you can imagine, there's a lot of anxiety around this. I know of people walking around grocery stores and leaving with eight cases of bottled water, even though the city of New Orleans itself won't see effects until late October. So there's just a lot of questions about how safe it will be to drink and bathe in the water. Plus, saltwater can actually be corrosive and damaging to pipes. New Orleans, like a lot of other areas, have a lot of lead pipes still left over. So there's concern about heavy metals leaching out.
CHANG: And areas south of New Orleans have already experienced problems with their water. So what's the plan for them?
PARKER: So a sparsely populated area southeast of New Orleans called Plaquemines Parish actually didn't have clean tap water starting in June.
CHANG: Wow.
PARKER: And at that time - yeah - it was confined to about 2,000 people without water. And the local parish ended up distributing more than 1.5 million gallons of water - a ton. And as the saltwater moves north, it might affect drinking water for nearly a million people. So officials across all levels of government know that they have to scale up response. Right now they have an underwater barrier to slow the salt water to buy them time. There's plans to eventually ship in up to 36 million gallons of fresh water per day to help water treatment plants dilute the salt and keep it to safe levels, which will take a lot of giant barges.
CHANG: Right.
PARKER: And if the salt level becomes unsafe or starts to affect infrastructure, we'll start to see distribution of bottled water and bulk water across this region just like we did in Plaquemines Parish.
CHANG: Do you think there's a chance that this kind of situation will happen more often in the future?
PARKER: Well, you know, as the sea levels just continue to rise and weather like droughts grow more extreme due to human-caused climate change, the experts that I talked to say that this is unlikely to become a new normal, which is important. But we could start seeing it more frequently, and that means we need to start thinking about long-term adaptation.
CHANG: That is Halle Parker of WWNO in New Orleans. Thank you so much, Halle.
PARKER: Thank you, Ailsa.
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