Corps to barge 36M gallons of freshwater a day to help areas facing saltwater contamination - NOLA.com

Corps to barge 36M gallons of freshwater daily to fight salt | Environment | nola.com

The Army Corps of Engineers is working to have 36 million gallons of fresh river water a day transported by barge to the New Orleans area to be used by local public water supplies facing contamination from saltwater moving upriver from the Gulf of Mexico, Corps officials said Friday.

"These barges, once approved for the transportation of water, will be filled with Mississippi River water from upstream," said Corps spokesperson Ricky Boyett.

The freshwater from the barges would be mixed with water being taken from the river at the water plants to reduce salt content to safe levels.

As of Friday, only St. Bernard and Plaquemines parishes had formally requested such aid, Boyett said.

Gov. John Bel Edwards has scheduled a 3 p.m. news conference in New Orleans to talk about state efforts to deal with the saltwater threat to local water supplies.

Concerns about the saltwater threat has led to bottled water was flying off the shelves at stores in Orleans and Jefferson parishes, but local leaders say there's no need to stockpile.

In fact, buying up bottled water is hurting the folks that really need it, said Patrick Harvey, Plaquemines' emergency preparedness director.

"The people that really need it in Venice and other parts of Plaquemines are having a hard time getting water," he said. "I compare what's happening to when people started buying all the toilet paper during the COVID (pandemic). They're stockpiling, but they're not impacted."

The leading edge of saltwater moving north in the river was at mile 66 above Head of Passes on Wednesday, or just north of Alliance in Plaquemines Parish.

That's still 21 miles south of the water intake in Belle Chasse. Last week, the Corps estimated the saltwater could reach Belle Chasse by Oct. 3 and a St. Bernard Parish water intake by Oct. 8, but by Wednesday, the water had already moved faster upriver, topping a saltwater sill at mile marker 63.8 that was designed to block its flow.

The Belle Chasse water plant produces 7.5 million gallons of water a day, while St. Bernard's water treatment plan produces 12 million gallons a day.

The water intake for the Algiers treatment plant is between river miles 95 and 96.

On Friday, New Orleans Mayor LaToya Cantrell filed an emergency order in Civil District Court that would give city agencies special powers if the saltwater does reach the city, including beefing up enforcement of looting laws and the authority to open emergency shelters.

The city now produces 148 million gallons of drinking water a day from freshwater on the east bank and 12.5 million gallons a day in Algiers. Jefferson Parish produces 70 million gallons a day from plants on the east and west banks.

In Plaquemines Parish, officials are working to connect parish water lines to those in Jefferson Parish and New Orleans, Harvey said. It also continues to seach for three reverse osmosis units that would be installed at lower parish water plants to remove saltwater. Two would be placed at the parish's Port Sulphur treatment plant, which is still being rebuilt following major damage during Hurricane Ida in 2021.

"They're hard to come by," Harvey said. "We've been searching throughout the United States."

For Venice, he said, the effects of the saltwater intrusion can be tasted in the tap water.

“It’s salty,” Harvey said. “It’s like going to the beach and getting a mouth full of water from the Gulf.”

Mike Steele, a spokesperson with the state Governor's Office of Homeland Security and Emergency Preparedness, said only Plaquemines had asked for his agency's assistance involving their water supplies as of Friday morning.

“Our support is based on what water supplies local (providers) have and what exceeds their capacity,” he said.

Jefferson Parish, which already has been supplying some water to Plaquemines via a pipeline, reiterated Friday that it has not yet been impacted by the saltwater, said Gretchen Hirt Gendron, a spokesperson for the parish.

The Corps informed shipping interests on Wednesday that the cutterhead dredge JS CHATRY would begin work on Friday to elevate the emergency sill by about 20 feet by dredging material from the bottom of the river upstream and transporting it by pipeline to the barrier. But that project will still include a wide notch in the channel to allow ocean-going vessels to go upriver, which will limit its effectiveness on slowing the upriver flow of the saltwater.

That saltwater moving upriver to threaten water supplies is an issue during Midwest drought years is not unexpected, said Ioannis Georgiou, a geologist with the Water Institute of the Gulf.

A wedge of saltwater that has been moving up the Mississippi River from the Gulf of Mexico, thanks to extremely low flows on the river, has al…

A portion of the lower river was dredged to 45 feet below sea level in 1988. In anticipation, in 1987, the Corps announced that it had awarded a contract to a local company to build barge moorings for freshwater offloading near the Plaquemines Parish's East and West Pointe a la Hache and Boothville water treatment plants.

And in late 1988, saltwater was tracked as far north as the river's Carrollton Bend in Kenner. That year, it moved upriver more quickly than the Corps' efforts to build a similar blocking sill.

Georgiou pointed out that the bottom of the river’s navigation channel was below sea level to at least Baton Rouge. Saltwater from the Gulf is heavier than freshwater and will move upriver in that channel unless forced out by the pressure resulting from the flow of lighter freshwater.

This year, that flow is dramatically reduced, to an estimated 130,000 cubic feet per second, compared to normal flows of 300,000 cfs or more.

“if there’s nothing to hold it back, which is the case now, it’s going to keep going upriver until it stabilizes and the forces (of freshwater flowing south and saltwater flowing north) are balanced,” he said.

The dredging of the channel to 50 feet below sea level in 2022 helped water from the Gulf move northward through the lowest part of the river, but even in New Orleans and St. Bernard Parish, the river bottom already was as much as 200 feet below sea level.

The bigger question is whether the saltwater will fill that entire space to close to the surface, where the public water supply intakes are located, often at 12 feet below sea level. That will determine whether New Orleans and Jefferson Parish will need additional water barged in to protect their water supplies.

This year's low river problems is also likely linked to failures by the Corps to require closure of a variety of relatively new pathways for freshwater out of the lower river, including the new Neptune Pass, said Sean Duffy Sr., executive director of the Big River Coalition, which advocates on river issues on behalf of companies that use the river.

Duffy said saltwater is actually using these new pathways to enter the river, speeding its flow upriver during low river periods, just as they have sped the exit of freshwater from the main river channel during other times of the year, threatening shipping and resulting in downriver shoaling that requires additional dredging.

Staff writer Tristan Baurick contributed to this story.