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What to Know About the Saltwater Threat to Louisiana’s Drinking Water Supply

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Updated: | Originally published:

Efforts to combat the drinking water crisis in the greater New Orleans area caused by a long-lasting drought in Louisiana appear to be working. 

State and local officials have been sounding the alarm for weeks after recording low freshwater levels in the Mississippi River, making it vulnerable to a process known as saltwater infusion, which brings an influx of saltwater from the Gulf of Mexico. But new data shows that the saltwater wedge has retreated more than five miles, and may no longer impact New Orleans’ water treatment plants, thanks to recent precipitation and the construction of a sill. Other cities, like Belle Chasse, however, are still expected to be impacted by the saltwater wedge though the date has been delayed to Oct. 27.

This marked the second year in a row when drought has decreased the flow of the water in the Mississippi River, causing much of the central and southern regions of Louisiana to face  exceptionally high drought levels.

On Sept. 27, President Joe Biden approved the state’s emergency declaration, authorizing the Federal Emergency Management Agency (FEMA) to help coordinate all relief efforts. 

“I’m grateful to the Biden administration for making this request a priority and responding quickly to help the people of South Louisiana,” said Louisiana Gov. John Bel Edwards said in a press release in late September. The governor sent a request for federal assistance two days prior, citing a situation of “severity and magnitude” that could no longer be managed locally. 

Here’s what to know about Louisiana’s water emergency.

What is happening in the state?

When climate conditions are balanced, the movement of freshwater stops saltwater from infiltrating bodies of freshwater. But in a process called saltwater intrusion, the zone of transition between saltwater and fresh groundwater is affected and saltwater enters the aquifer, reducing the amount of freshwater.

Droughts are relatively common in Louisiana, where periods of dryness are a natural part of their climate. But global warming is increasing the risk of drought all across the country. The Southwest is expected to be particularly affected by droughts that occur more frequently, intensely, and for longer periods of time, according to the Center for Climate and Energy Solutions

“Most of the state has been experiencing prolonged drought and above-average heat, and has presented a number of challenges including wildfires, drought, heat-related deaths, injuries and so forth and now saltwater intrusion,” said Edwards during a Sept. 22 press conference.

How are officials trying to combat it? 

Officials have implemented a number of projects to attempt to prevent the saltwater wedge from encroaching on freshwater, starting with expanding an existing underwater sill that was first built in July 2023 in the Mississippi River. Authorities have been working on expanding that sill by 25 feet since late September. Its construction has delayed the salt water’s impact on drinking water in the greater New Orleans area but still presents a problem for communities like  Dalcour and St. Bernard. Water treatment facilities in Plaquemines Parish, however, have already been impacted by the intrusion.  

“The positive news from the corps is due to a larger surge of water coming down the Red River after some heavy rains in Texas and Oklahoma several days ago. This, in combination with fronts along the Gulf Coast keeping persistent northerly winds over us, helps the fight of the salt water wedge,” said Meteorologist Zack Fradella. 

Officials previously said that the best shot at preventing greater saltwater intrusion was through precipitation, which is expected to come at above average amounts come winter, according to Edwards. 

Officials are also using  reverse osmosis units—which make water drinkable—and water barging to help deal with the saltwater intrusion. The U.S. Army Corps of Engineers previously committed to sending 36 million gallons of freshwater daily to affected areas in southern Louisiana by barge. Reverse osmosis machines were also installed in Plaquemines Parish, but authorities say that these additions are insufficient to deal with the problem at hand. 

At a recent public works committee board meeting, officials also spoke about adding a 14-mile pipeline that would help deliver freshwater upstream from north of the city of Kenner, Louis. Construction has already begun on the Jefferson Parish pipeline. Its construction would cost anywhere from $100 to $250 million. 

Collin Arnold, director of homeland security and emergency preparedness for the city of New Orleans, says he hopes the city will be reimbursed for part of that cost from the federal government. Other officials have said that they are also considering bringing in desalination units or digging underwater wells. For now, authorities advise residents to remain calm but be prepared to begin conserving water in the next few weeks. “We’re not in a doomsday situation,” Arnold said during the meeting. 

How is climate change impacting the state of Louisiana?

A 2016 Enviornmental Protection Agency report predicted that climate change in Louisiana would bring about severe floods and droughts, with rainfall expected to “arrive in heavy downpours,” impacting the soil’s health.

The Mississippi River has been at the center of climate emergencies for years, as intense flooding impacted the region in 2019, a year that was particularly rainy. Now, in 2023, we're seeing the opposite. In August, residents were impacted by the Tiger Island Fire—the largest wildfire in Louisiana’s history—which forced 1,200 people to evacuate and took down at least 20 homes and structures. That same month Gov. Edwards issued a state of emergency due to record-breaking heat levels after temperatures reached the mid-90s and low-100s for weeks.

Aside from concerns about access to drinking water, increased temperatures due to climate change have already impacted people’s health. The state passed its average number of heat-related deaths and emergency room visits in mid-August, according to local public radio station WWNO.

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