Coastal Desk

We answer your questions about the saltwater wedge in the Mississippi River

WWNO - New Orleans Public Radio | By Halle Parker,

Published September 27, 2023 at 10:15 PM CDT

In this aerial photo, a tugboat pushing barges navigates around a sandbar during low water levels on the Mississippi River between Baton Rouge, La., and Reserve, La., in Livingston Parish, La., Thursday, Sept. 14, 2023. (AP Photo/Gerald Herbert)

Updated Oct. 11, 2023 at 7:50 a.m.

As salt water moves up the Mississippi River from the Gulf of Mexico, residents across the greater New Orleans area have been left with many questions. This isn’t the first time a so-called saltwater wedge has threatened drinking water this far north. But the intrusion could last longer than usual this time, and that possibility has fueled anxiety among many residents about what’s to come.

Government officials at all levels have expressed the same message: There’s no need to panic.

But to give a fuller explanation of where we stand now and what you can expect if the wedge continues its northward progression, we’ve put together a guide to answer some of the most common questions readers are asking. We'll update this until the salt water retreats.

You have more questions? Ask them on our thread on X, formerly known as Twitter, or email hparker@wwno.org.

Hey ya'll, I'm working on an article to break down what's happening with this saltwater wedge. I want to make sure I answer your questions -- what's on your mind?
— Halle Parker (@_thehalparker) September 25, 2023

Shortcuts:

What is a saltwater wedge? Why is it happening?

The entire Mississippi River Valley is in a historic drought, so far less water is flowing down the river than usual. When that happens, salt water from the ocean can migrate upriver along the river’s bottom, which is below sea level throughout the entire length of Louisiana. The denser salt water sinks beneath the river’s freshwater during periods of low flow and slowly pushes north.

Has this happened before?

Yes. Salt water intrudes up the Mississippi River about once every decade. It happened in 2012 and again in 2022. The ocean water usually doesn’t come this far north, but it isn’t unprecedented. The salt water reached Kenner in 1988 but only stuck around for a few days before retreating. This year, the intrusion has the potential to last weeks. It’s also unusual for this phenomenon to occur in back-to-back years.

Just how salty is this wedge?

Well, it depends. According to Ricky Boyett, New Orleans District spokesman for the U.S. Army Corps of Engineers, salinity varies throughout the water column — with water at the bottom being saltier than water at the top. While their online tracker shows the location of the “toe,” or the leading tip, he said the Corps is more concerned about the portion of the wedge trailing about 15 miles behind the toe, where the salinity of the river’s surface reaches 250 ppm.

How much salt is usually in our water?

On average, New Orleans has 30 parts per million to 50 parts per million of salt in its water on any given day, according to Steve Nelson, a deputy superintendent of Sewerage & Water Board of New Orleans. That level is similar to most water systems throughout the country.

How long will it take for the wedge to reach all of the water treatment plants in the greater New Orleans area?

The estimated timeline could change depending on the weather conditions throughout the Mississippi River Valley and the speed of the saltwater wedge, but this is the current projection:

Oct. 13: Belle Chasse
Oct. 17: Dalcour
Oct. 28: St. Bernard
Nov. 23: New Orleans Algiers
Nov. 26: Gretna
Outside of forecast: West Jefferson, Westwego, New Orleans Carrollton, East Jefferson

Could it affect people beyond Jefferson Parish?

Depending on how long we go without extensive rainfall in the upper Mississippi River basin, St. Charles Parish would be the next locality beyond Jefferson Parish to potentially see effects. But St. Charles’ water treatment facility is much farther upriver from East Jefferson, Boyett said, so it would take longer to arrive there and is still beyond their current forecast ability. The Corps’ forecasts can only look 28 days into the future because that is also the farthest out that the National Weather Service makes its projections.

Will people in Jefferson, Orleans and St. Bernard lose access to drinking water like in Plaquemines Parish? What happens then?

The short answer: it is too early to tell if or what kind of water restrictions we might see as a result of the saltwater wedge. That’s according to government officials and local water advocates like the Water Collaborative, a New Orleans nonprofit. But residents should be prepared to conserve water and store tap water in bulk in reusable containers at home — an alternative to bottled water — in case there is a disruption. The Corps has told the city to prepare for the saltwater intrusion to stay for 90 days. New Orleans Office of Homeland Security and Emergency Preparedness spokeswoman Anna Nguyen said the city’s Sewerage and Water Board doesn’t expect any problems at its water treatment plants and plans to maintain water access until the saltwater wedge dissipates.

But if there are disruptions, Nguyen said SWB has committed to informing customers well in advance. New Orleans, Jefferson, the Governor’s Office for Homeland Security and Emergency Preparedness and the National Guard are developing a “robust water distribution plan” and ensuring local stores have enough water and ready-to-feed formula for infants.

“No matter the salinity levels, water will be available to customers for wastewater purposes, including flushing the toilet and bathing, as well as fire suppression,” Nguyen said.

Should I prepare? If so, how?

You should prepare to some extent. Residents across Plaquemines, St. Bernard, Jefferson and Orleans parishes should be ready to conserve water to relieve pressure on the system as needed, depending on how long the salt water stays up north. On Wednesday, NOHSEP Director Collin Arnold said New Orleans is preparing for the saltwater intrusion to last into January.

Experts say you should not panic buy bottled water. “When people panic buy or purchase, they are creating more scarcity,” said Nina Cleveland, adjunct professor of emergency and security studies at Tulane University.

Local officials say packaged water should be preserved for areas that are already experiencing impacts, like Plaquemines Parish.

You can prepare by filling reusable containers with tap water now, that way you’ll have it if you need it. Now is also the time to call your appliances’ manufacturers to figure out what effect salt water could have on them and at what salinity level you should start to worry.

Also, make sure you have trusted sources for news outside of social media posts that can be inaccurate and fuel unnecessary anxiety. GOHSEP has established a landing pagewith resources and frequently asked questions that will be updated regularly.

The Corps plans to barge fresh water to some treatment plants. Where will that water come from?

The exact location hasn’t been determined yet. But Boyett said the Corps will draw water from a portion of the Mississippi River upstream from the toe of the saltwater wedge. It won’t be taken from the top of the river, which is constantly in motion, stirring up pollutants. The Corps is testing water in different locations to make sure what they ship is safe and not contaminated with outfall from nearby industrial facilities. They’re also trying to cut barge transportation time as much as possible. When the barging starts, giant “reservoir barges” will be parked next to treatment plants and attached by temporary pipes, then other barges will travel up and down the river, refilling the reservoirs as needed.

The Corps hopes to be able to draw from the same location for “a long period of time,” Boyett said.

He said it will take a lot of barges to ship 36 million gallons of water a day — since they range in capacity from 100,000 gallons to 1 million gallons — and the Corps is still securing more barges to meet that need. Barged water will only be used to dilute water for the water treatment plants south of West Jefferson Parish starting in Gretna.

Plaquemines Parish's Port Sulphur plant has a "reservoir barge" in place. It has received at least half a million gallons of water so far, according to the Corps.

Barges won’t work for larger water treatment plants in New Orleans and Jefferson Parish. What’s the plan for them?

Officials in both New Orleans and Jefferson Parish have plans in place to rapidly build emergency freshwater pipelines that pull water from upriver to serve their treatment plants if the saltwater wedge threatens to reach them.

The Sewerage and Water Board of New Orleans, SWBNO, has started designing a pipeline to serve the Carrollton water plant, which provides 141 million gallons of drinking water a day, according to SWBNO’s annual report. The cost to build the pipeline could range from $100 million to $250 million, according to NOHSEP Director Collin Arnold.

Arnold said the goal is to finish construction within a month. He estimated it would take between 25 and 45 days to construct the pipeline.

“Every day we're not building [the pipeline] is a lost day,” Arnold said during a city council committee meeting on Sept. 27. Some city officials have said they’d like to make the pipeline permanent, but it isn’t clear whether that will happen.

In Jefferson Parish, officials plan to build two temporary pipelines that would draw in freshwater from a similar location as New Orleans’ pipeline and connect to the East and West Jefferson treatment plants, Parish President Cynthia Lee Sheng said Friday.

The East Jefferson plant pumps 30 million gallons daily, while the West Jefferson plant pumps 40 million gallons per day.

Both parishes have already scouted a route for the pipelines. Jefferson Public Works Director Mark Drews said the parish hopes to bring in equipment and start construction this week.

Will schools have to close?

Different school systems are taking similar steps and said closures aren’t likely.

In St. Bernard, the school system has purchased bottled water and will buy more as needed, said Sara Felt, the school district’s spokesperson. The district has already changed its food menu to accommodate possible water restrictions. Officials don’t plan to switch to remote classes but can if needed, she said.

Public schools in New Orleans and Jefferson Parish have launched a coordinated response. They haven’t purchased bottled water yet, but plan to if needed, and will share full salt water guidelines with schools.

Some steps the districts say they could take, if water becomes unsafe, include:

Buying and distributing bottled water to schools
Disconnecting school kitchens from water lines
Changing lunch menus to rely on microwave-friendly and pre-packed foods
Purchasing reverse-osmosis systems to filter water in school kitchens
Monitoring heating and cooling systems to limit saltwater exposure, which can cause damage over time

Read the whole story.

The school district in Plaquemines Parish, which has already experienced water quality issues, did not respond to multiple requests for comment.

Local colleges and universities say they’re also prepared to stay open if tap water gets too salty. Like K-12 schools, they plan to take preventative steps to protect facilities and use bottled water as necessary.

Would drinking saltier water hurt my health?

Even in areas that are affected, Louisiana Department of Health officials say most healthy people will not see any impact from the water. But people who are more vulnerable to a higher salt diet due to pregnancy, kidney disease or high blood pressure should be vigilant.

If the salt content surpassed 250 parts per million (ppm) or milligrams per liter (mg/L), Nguyen said the utility will issue an advisory. That level is when the Environmental Protection Agency says the water starts to taste salty — but not necessarily present a threat to health. In the southern end of Plaquemines Parish, the salinity of the tap water exceeded 1,600 ppm at its peak, more than six times the EPA’s standard.

Plaquemines residents had their water restored on Monday, Sept. 25, after a water treatment plant that hadn’t been functioning for two years came back online and boosted the parish’s water capacity. Most residents can now safely drink the tap water, which has a salt level of 140 ppm as of Wednesday, according to the parish’s emergency preparedness director Patrick Harvey.

Can I bathe and brush my teeth with salty water?

Louisiana Department of Health spokesman Kevin Litten said this question is a bit premature, as no water advisories outside of Plaquemines Parish have been issued and water is still safe. But in the event of a saltwater advisory, the answer is yes, you can still bathe. In fact, bathing in saltier water can actually have benefits for your skin, as long as you aren’t allergic. Most people aren’t. And yes, it is safe to brush your teeth as well — kind of like a saltwater rinse.

Can we filter the salt out at home?

You can’t filter it out with conventional filters like a Brita. Technically, at-home reverse osmosis systems exist, but they’re expensive and often unnecessary. You also can’t simply boil water to remove salt. Larger-scale reverse osmosis filters are being sent to some water treatment facilities to help them maintain clean drinking water for residents. Reverse osmosis units push water through a very thick filter with tiny holes using extremely high pressure to separate the salt. Most homes don’t have the ability to push water at that high of pressure.

Salt water is corrosive. How could this affect water lines and home appliances?

This is a big question, and the answer will continue to develop. Anecdotally, residents in south Plaquemines Parish have reported problems and costly damage to their home appliances and have attributed it to the salt water, according to Harvey. They dealt with weeks of exposure to salt levels at 1,600 ppm, more than six times higher than the standard for salt in drinking water.

The biggest casualties? Water heaters and ice makers. Others reported damage to washing machines and dishwashers.

Harvey said Plaquemines is looking into whether a new disaster declaration issued by the Federal Emergency Management Authority will allow residents to apply for money to help with repairs. The current guidance from the Louisiana Department of Health recommends calling your appliance manufacturers for advice.

Corrosion of water lines remains a serious concern depending on how long the salt water sticks around. New Orleans alone has at least 50,000 lead pipes still in use, according to Mayor Latoya Cantrell, and the salt water could cause those pipes to leach heavy metals. Jefferson Parish is still studying their water system to search for lead pipes. Nguyen said New Orleans and Jefferson Parish are also working with the Louisiana Department of Health to craft a daily monitoring plan and “a robust corrosion detection and public notification plan.” Those will be developed in the coming weeks.

In Jefferson Parish, they’re treating water lines with a type of phosphate to prevent corrosion, according to Sidney Bazley, director of the parish’s water department.

Could there be any effect on Entergy or underground cables?

Utility companies like Entergy Louisiana and Entergy New Orleans don’t anticipate any impacts to their operation, equipment or power generation facilities.

“Entergy is actively monitoring the effects of the Mississippi River’s saltwater intrusion in south Louisiana,” said a spokesperson for Entergy New Orleans. “We remain watchful for any longer-term impacts and are prepared to mitigate them as needed. Entergy teams are in regular contact with state and local emergency officials.”

The river is low. Can I take a swim?

Though the river level is low, no one should try to wade or swim in the Mississippi River. Boyett, with the Corps, said while the river's surface might appear calm right now, the current is still violent underneath due to the river's uneven bottom. It's also still very deep, at least 50 feet deep in a lot of places. Near Algiers, it's 190 feet deep. It is not safe for swimming.

Can I garden with the water?

Most plants can handle water with a salinity up to 1,000 ppm, according to the LSU AgCenter. But salt can build up in the soil if there isn’t rain to flush it out. Read more here.

Would a government shutdown affect its response to the saltwater emergency?

Short answer: No. The Corps and FEMA will continue to operate in response to the emergency even during a shutdown, according to officials with both agencies. A FEMA spokesperson said the agency is running low on money, resulting in delays to other programs like public assistance payments and hazard mitigation projects, but disaster response remains its funding priority.

How much rain is needed to push the saltwater wedge back?

Col. Cullen Jones, the Corps’ New Orleans District commander, has said we need 10 inches of rain to fall across the Mississippi River basin to boost the river, and it would still take time for that water to make its way down south. It would take another 4 to 6 weeks for that water to make it to the mouth of the Mississippi. Jones said the river had a flow of 150,000 cubic feet per second — half of what’s needed to push back the salt water as of Sept. 27

How often should we expect this type of saltwater intrusion moving forward?

Researchers don’t know exactly how often we can expect this level of saltwater intrusion to happen in the future. Tulane University Bywater Institute Director John Sabo said this has the potential to happen more frequently, in part due to sea level rise and the worsening droughts that have resulted from human-caused climate change, among other factors. But the saltwater wedge shouldn’t be considered a “new normal.”

He said that more frequent intrusion does, however, call for long-term adaptation measures to ensure localities in southeast Louisiana aren’t scrambling if this happens again. Jones said the Corps is researching the issue as part of its 5-year Lower Mississippi River Study that began this year in June. The $25 million study won’t be complete until 2028.