A massive influx of saltwater from the Gulf of Mexico is surging up the drought-stricken Mississippi River, posing a threat to the drinking water supplies of around 900,000 Louisiana residents. This alarming situation has officials scrambling to find solutions and minimize the impact of this intrusion.
“We are facing a very challenging situation where saltwater is pushing its way upstream,” stated Louisiana Governor John Bel Edwards during a press conference. He was joined by state and local leaders, emergency officials, and representatives from the U.S. Army Corps of Engineers.
Governor Edwards, a Democrat, acknowledged the efforts of the Army Corps of Engineers in addressing the issue. However, he emphasized that the dry conditions in the region have not provided enough relief, resulting in the worsening of the saltwater intrusion.
New Orleans Mayor LaToya Cantrell declared a state of emergency for the city, while Governor Edwards announced plans to request a federal emergency declaration from Washington to secure additional aid for Louisiana.
“In the next few days, we will be seeking an emergency declaration from the federal government to involve more federal agencies that can provide assistance,” he stated.
With A view of the Mississippi River to the left and the Gulf of Mexico to the right, in Buras, La., on Aug. 22, 2019. (Drew Angerer/Getty Images)
Drinking Water in Focus
Under normal circumstances, freshwater flows downstream along the Mississippi River, pushing against the salty water from the Gulf of Mexico and preventing its intrusion.
However, due to historically low rainfall in the Mississippi River basin, a drought has weakened the river’s ability to keep the saltwater at bay, putting the region’s drinking water supplies at risk.
“There is no need to panic,” reassured Governor Edwards, emphasizing that efforts are underway to mitigate the impacts of the saltwater intrusion. Ensuring the availability of safe drinking water remains the top priority at this stage.
Municipalities in southeast Louisiana, including New Orleans, rely on the Mississippi River as their source of drinking water. The encroaching saltwater wedge poses a contamination threat to the freshwater intake.
“Our primary focus is to ensure that we have an ample supply of safe drinking water for the affected population,” Governor Edwards affirmed.
A road dead ends near the bank of the Mississippi River Gulf Outlet, which is now closed to maritime shipping due to extensive saltwater intrusion, erosion, and degradation of the surrounding wetlands, in Shell Beach, La., on Aug. 22, 2019. (Drew Angerer/Getty Images)
The saltwater wedge has already traveled approximately 15 miles upstream in just seven days, according to Colonel Cullen Jones, Commander and District Engineer of the New Orleans District, Army Corps of Engineers.
Colonel Jones explained that saltwater intrusion becomes a concern when the flow of the Mississippi River drops to around 300,000 cubic feet per second. Currently, the flow is much lower, at approximately 148,000 cubic feet per second.
To restore the flow above 300,000 cubic feet per second, the entire Mississippi Valley would require around 10 inches of rainfall.
However, such rainfall is unlikely, which means the saltwater wedge could impact local water systems for a period ranging from a few weeks to a couple of months.
Mitigation Efforts
Colonel Jones revealed that the state and the Army Corps of Engineers are working on raising the height of a 1,500-foot-wide underwater levee in the Mississippi River by 25 feet. This levee, constructed in July, aims to slow down the intrusion of saltwater.
Colonel Jones estimated that the construction process would take approximately 24 days and delay the progression of the saltwater wedge by 10 to 15 days.
However, he cautioned that without substantial rainfall, the underwater levee would be overtopped. In such a scenario, there is a contingency plan to transport freshwater by barge to local water treatment plants.
“Simultaneously, we are establishing the capability to transport freshwater via barges to municipal water treatment facilities, ensuring the production of safe drinking water at the local level,” explained Colonel Jones.
Initially, 15 million gallons of freshwater are expected to be transported by barge next week, with plans to increase this amount to as much as 36 million gallons per day, as needed.
During the press conference, a health official stated that when the salt concentration (sodium chloride) exceeds 250 parts per million, water systems issue a health advisory. However, he reassured the public that for taste reasons, most people would stop consuming the water well before it becomes a health hazard.
Reports have already emerged of people rushing to stock up on bottled water in certain parts of Louisiana. Governor Edwards urged residents not to panic-buy large quantities of bottled water, assuring them that there is no shortage in the state and businesses have been asked to increase their inventories.
Eks to several months, according to experts.
In response to the saltwater intrusion, the Louisiana Department of Health has implemented measures to protect the drinking water supply. These measures include extensive monitoring of the water quality, adjustment of treatment processes, and increased communication with water system operators.
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