Here are the options to fix New Orleans saltwater intrusion for good. How much will it cost?

Thanks to a changing climate and a deeper navigation channel in the Mississippi River, the saltwater intrusion that has threatened New Orleans area drinking water supplies this year is expected to become more frequent.

The scale of the crisis has sparked calls for a permanent solution. While there is no shortage of ideas, they all come with a huge price and no certainty about who will pay for them.

One favored plan would involve redesigning and rebuilding plants serving New Orleans and Jefferson Parish to allow them to remove salt from river water, projects that could cost hundreds of millions of dollars, parish officials say.

Ghassan Korban, executive director of the Sewerage & Water Board of New Orleans, said dealing with the saltwater threat is being added to proposals already being considered to upgrade the city’s outdated Carrollton and Algiers water treatment plants to be able to remove other toxic substances, including lead, copper and multiple varieties of PFAS “forever chemicals.”

Jefferson Parish agreed to join the New Orleans water board in exploring the potential of adding desalination technology to its water plants as a practical, cost-effective solution to the saltwater problem, said Jefferson Public Works Director Mark Drewes.

Jefferson Parish also is considering installing a new permanent water intake north of the so-called “Kenner Hump” on the Mississippi River, where a naturally elevated water bottom sill might halt the movement of salt water further upstream. The new collection location, about 10 miles north of the parish's east bank water plant, would be connected by a new permanent system of pipelines and pumps to existing water plants.

The parish’s experimental temporary pipeline system on the West Bank will be collecting water in about the same location.

Korban said an early rough estimate of the treatment plant reconstruction costs for New Orleans is at least $200 million.

Jefferson Parish officials did not have an estimate for their treatment plant upgrades, but said a permanent pipeline system's costs would be similar to the expected price of using temporary lines on both sides of the river for several months. That would amount to a total of nearly $40 million if the crisis were to last three months, the timeframe both parishes had been preparing for before a recent change in forecast put them in the clear through December.

This video shows a simulated run of the model the Army Corps of Engineers is using to estimate the movement of salt water up the Mississippi River to the location of an underwater sill built to slow its upstream movement, and beyond. On Monday, Oct. 30, 2023, the salt water was at river mile 66.8, and the sill is at river mile 63.8. (Army Corps of Engineers)

Both options were discussed by the S&WB and Jefferson Parish officials with representatives of the White House, FEMA, the Army Corps of Engineers and the Governor’s Office of Homeland Security and Emergency Preparedness during an Oct. 12 meeting, Drewes and Korban said.

The long-term solutions are in part driven by the expectation that global warming will continue to cause sea levels to rise, resulting in more frequent saltwater intrusions.

Lack of rainfall runoff due to drought throughout the Mississippi River basin, combined with the deepening of the river below New Orleans for larger ocean-going cargo ships, has allowed Gulf of Mexico salt water to move north. 

Reverse osmosis

St. Bernard Parish also is considering upgrades to its water treatment facilities to remove salt that it estimates will cost about $30 million, said parish President Guy McInnis.

Plaquemines Parish, which has been dealing with salt water intrusion on an emergency basis for months, is looking into a variety of long-term fixes, including installation of permanent reverse osmosis equipment to remove salt at its Pointe a la Hache and Boothville-Venice plants, said parish President Keith Hinkley.

It’s also looking at relocating a redesigned Port Sulphur plant far enough north that its water intake would be upriver of the temporary saltwater-blocking sill built across the river bottom by the Corps, Hinkley said. The redesign would be aimed at also being able to deliver enough water to service Belle Chasse during intrusion events.

The new plant would also use permanent reverse-osmosis equipment to remove salt from water, he said.

Improvements at the three Plaquemines water plants could cost as much as $150 million. Adding pipeline improvements — including replacement of pipe likely eroded because of this year’s salt water — could push the cost to as much as $300 million, Hinkley said.

The sill built to block the northward flow is located at mile marker 63.8, near Myrtle Grove, and would be built in that location again when saltwater advances in the future. The Corps has extended a contract with a dredging company to keep the sill at the proper elevation through Nov. 30. Once water on the lower river resumes a normal flow rate, the existing earthen sill will erode naturally.

Hinkley and McInnis said they also will continue to push the Corps to block the flow of water out of the river at dozens of natural crevasses below New Orleans, including Mardi Gras, Neptune Pass and cuts around Port St. Philip.

Building reservoirs?

U.S. Rep. Garret Graves, R-Baton Rouge, suggested another alternative in a Sept. 28 letter to Col. Cullen Jones, commander of the Corps’ New Orleans District: creating new or expanding existing reservoirs along the river to capture freshwater during high-river periods that could be released when the river is low.

Graves asked that his proposal be considered as part of the Corps’ Lower Mississippi River Comprehensive Management Study, authorized in 2020 but delayed for several years when the Corps required Louisiana to pay part of the study cost. Graves included language in water resources legislation last year that requires the study to be paid for with 100% federal funds, and later legislation provided enough money to begin work on the study.

Dealing with saltwater intrusion is only the latest of a number of controversial issues that the study is supposed to address. A separate study of long-term measures to address saltwater intrusion’s impact on drinking water supplies would require congressional approval and funding, said Ricky Boyett, a spokesperson for the Corps’ New Orleans District office.

However, another alternative being considered by the parishes is turning to FEMA to see if President Joe Biden’s Sept. 27 saltwater intrusion disaster declaration can be interpreted to include long-term solutions. It was in that context that New Orleans and Jefferson Parish officials presented their proposals to White House officials two weeks ago.

FEMA has said reimbursement of the four parishes threatened by saltwater intrusion in connection with the emergency declaration is “limited to temporary measures." But if the threat requires residents and businesses to relocate, and relocation is not feasible, “FEMA is required to undertake a detailed review to determine what measures can be taken to minimize future damages.”

"FEMA has agreed to activate the long-term recovery function, which is a bit unique," said Casey Tingle, director of the Governor's Office of Homeland Security and Emergency Preparedness. "Typically, these long-term recovery missions are activated in response to a major presidential disaster. But in this case, we've got the emergency declaration and FEMA has agreed to activate that to go through a planning process to see what kinds of ideas they have."

He said it's still up to the individual parishes to determine what is feasible and present it to FEMA, which will then work with its federal partners, including the Corps, to identify technical and financial assistance. It could include the federal Economic Development Administration, Tingle said. 

That process has been used in the aftermath of major disasters in Louisiana, he said, including in St. John the Baptist Parish after 2012's Hurricane Isaac, in several Baton Rouge-area parishes after the 2016 floods; and in several parishes after Hurricanes Laura in 2020 and Ida in 2021.