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Friday, July 19, 2024 | Back issues
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New Orleans braces for saltwater wedge into water supply

An inundation of salt water — caused by low water levels in a drought-stricken Mississippi River — is expected to reach New Orleans' drinking water in the next few weeks.

NEW ORLEANS (CN) — New Orleans Mayor Latoya Cantrell signed an emergency declaration Friday that will allow city agencies to respond to an imminent intrusion of salt water into New Orleans’ drinking water supply.

Government officials estimate that the saltwater intrusion will reach the Crescent City’s fresh drinking water between October 22 and 24, affecting thousands, and lasting for weeks to months.

Low levels rainfall in the Ohio Valley and across the rest of the Midwest have reduced water levels in the Mississippi River, which serves as allowing salt water from the Gulf of Mexico to "wedge" upstream where it may threaten fresh water supplies throughout the state.

“There is no need to panic,” Louisiana Governor John Bel Edwards said during a Friday afternoon press conference on the matter at the Morial Convention Center in downtown New Orleans.

Despite his assurances, Edwards warned that there was no end to the drought in sight, and even if rain were to occur, the amount needed to stave off saltwater intrusion in the New Orleans metro area is extremely unlikely.

“Obviously, the most important thing to do is to ensure that we have plenty of clean drinking water,” Edwards said, though he cautioned residents not to panic and hoard water, which could potentially snarl the local supply chain.

“Be a good neighbor and don’t overstock,” Edwards said toward the end of the press event. “We can cause problems if there is irrational panic buying. I’m asking people to please not do what you did in 2020.”

The river has been low all summer and is only getting lower — with record-breaking levels expected this coming week.   

Normally, the flow of the river prevents salt water from the Gulf of Mexico from moving very far upstream, but throughout the dry summer, salt water has begun creeping northward.

In June, salt water entered the drinking supply for small communities in southeastern Louisiana's Plaquemines Parish, which lie between New Orleans and the Gulf of Mexico.

Plaquemines Parish President W. Keith Hinkley estimated earlier this week that about 2,000 Plaquemines Parish residents are already without water due to salt contamination. He said the parish has already distributed more than 1.5 million gallons of water.

To slow the progression of saltwater into the river, the U.S. Army Corps of Engineers constructed an underwater barrier downriver from New Orleans in July, though the barrier was breached this Wednesday. Construction on another ledge that is 25 feet higher is underway, but with a notch somewhere near the center to allow boats to pass through and prevent stalling critical maritime transportation.

Without considerable rain, this levee will also be topped eventually, Army Corps of Engineers Col. Cullen Jones said during Friday’s press conference.

Salt water from the Gulf of Mexico, known as a “saltwater wedge,” typically only occurs about once every ten years. But 2023 is the second year in a row where the Mississippi River’s levels have been far lower than usual.

The lowest recorded flow in the river was in 1988 and lasted a couple of days.

Col. Jones said this event will differ from 1988 in that it will likely last weeks to months.

“We would need to see approximately 10 inches of water across the entire Mississippi Valley,” Jones said. “We normally don’t see that kind of precipitation, so we’re expecting to experience this for weeks or months.”

Such long term saltwater intrusion can leach heavy metals into pipes. Government officials said they are prepared to step up water quality testing and keep an eye on contamination levels. Cantrell said the city has already been conducting an accounting of lead pipes across New Orleans for other purposes and is aware of over 50,000 lead pipes citywide. She said the city is preparing a plan to address saltwater intrusion into lead pipes.

Saltwater intrusion can also have medial implications for those who need to be on low salt diets, for pregnant women, particularly those in their third trimesters, and for infants on formula. But Dr. Joseph Kanter of the Louisiana Department of Public Health said during the conference that most people would likely stop drinking the water because of the salty taste long before it could cause them health problems.

Col. Jones, when asked if there is a contingency plan in place for a separate, bulk water supply for the city and surrounding area, said, “the sky’s the limit” and spoke of a possibility of pulling unaffected water from upriver.

“We do need some rain,” Governor Edwards said in closing. “I’m not in charge of that. I’m one who happens to believe in the power of prayer and I’m going to be praying for that.”

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Categories / Environment, Government, Health, National, Regional

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