Saltwater intrusion in the Mississippi River threatens drinking water in the New Orleans area

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The U.S. Army Corps of Engineers is building an underwater sill to help protect the water supply for southern Louisiana as saltwater from the Gulf of Mexico seeps up the Mississippi River.

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00:00 The New Orleans area is in danger of saltwater intrusion.

00:05 Saltwater from the Gulf of Mexico could kind of back into the New Orleans area, flowing

00:09 back into the Mississippi River, threatening drinking water and safety around New Orleans.

00:14 So the U.S. Army Corps of Engineers is working to stop that from happening before October.

00:19 Matt Rowe is a public affairs specialist and joins us now with the Army Corps of Engineers.

00:23 Matt, thank you so much for making time.

00:25 Absolutely.

00:26 Well, Matt, why is this a danger and what can happen when saltwater kind of creeps up

00:31 into the freshwater drinking sources?

00:35 This is a danger because a lot of the water intakes along the Mississippi River and the

00:40 parishes that sit in south Louisiana are not equipped to process water with a high chloride

00:46 level.

00:47 So as water from the Gulf of Mexico does seep up into the Mississippi River, they don't

00:54 have the ability to process that water into municipal drinking water.

01:00 So what is the U.S. Army Corps of Engineers doing regarding a levy that was created to

01:05 combat these low water levels?

01:07 When we see situations of low water on the Mississippi River coming down without enough

01:12 force behind it to keep the Gulf of Mexico at bay, we do construct an underwater sill,

01:18 which is essentially an underwater levy.

01:21 The base of it is wider than the top in an effort to slow down progression of the saltwater

01:27 as it moves upriver.

01:30 We've started construction to augment the existing sill that was in place earlier in

01:36 July and we're going to raise the sides of that up about 20 more feet while keeping the

01:42 center line open for shipping and navigation on the Mississippi River.

01:47 And the Mississippi River may continue to fall over the next few weeks with relatively

01:51 dry conditions for many areas upstream.

01:53 So what additional work needs to happen at this point?

01:56 So in addition to augmenting the sill that we built in July, the Corps of Engineers is

02:01 in the process to barge water downstream to the impacted treatment facilities.

02:08 They'll be able to blend that with water from the river to bring those chloride levels down

02:12 to a treatable level.

02:14 And what kind of volume of water might be transported in this case?

02:20 The Corps of Engineers, we're working right now to see what barges we have on hand.

02:26 Could be millions of gallons a day to some of the treatment facilities that are going

02:30 to be impacted by the saltwater.

02:32 And Matt, how often does this happen?

02:33 I mean, you remember it comes back from last fall where we had low water levels for the

02:38 Mississippi.

02:39 I suspect it doesn't necessarily happen every year.

02:42 So historically, how are we stacking up here?

02:47 Historically we've seen saltwater come this far up the Mississippi River about every 10

02:50 to 12 years.

02:53 The Corps of Engineers has to build the underwater sill as a mitigation to the deep draft ship

02:58 channel in the Mississippi River.

03:00 So the first time it was constructed was 1988.

03:03 Then we saw this saltwater intrusion again in 1999, 2012, and then last year and this

03:09 year.

03:10 So that's the historic part with this event of having two low water years where a sill

03:15 has needed to be constructed.

03:17 We'll be rooting for rain upstream as we move on through the next few weeks.

03:20 Matt Rowe, Public Affairs Specialist for the U.S. Army Corps of Engineers.

03:24 Thanks again so much, Matt.

03:27 Thank you.

03:27 [BLANK_AUDIO]

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