Officials in Louisiana are warning that saltwater coming up from the Gulf of Mexico could affect the availability of safe drinking water for millions of people along the Mississippi River, including those in New Orleans.
The so-called saltwater intrusion was triggered by a severe drought, with months of extreme heat and low rainfall leading to unusually low levels of freshwater in the Mississippi.
What are officials saying?
New Orleans Mayor LaToya Cantrell signed an emergency declaration last week, warning that saltwater encroaching upriver could impact safe drinking water for 1.25 million residents of the city and surrounding parishes.
Louisiana Gov. Bel Edwards sent a letter to President Biden earlier this week requesting that he approve a federal emergency declaration to assist those in the lower Mississippi River region affected by the saltwater intrusion.
“The rate of fresh water flowing down the Mississippi River has been low due to extended drought conditions in Louisiana and across the Mississippi River Valley,” Edwards explained in his letter. “As a result of these historic low flow conditions, an intrusion of saltwater from the Gulf of Mexico is making its way upriver.”
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Plaquemines Parish in southeastern Louisiana has already been impacted by the saltwater intrusion, the governor noted, as residents there have been under a drinking water advisory since June.
Edwards said that the “increased salinity” from the saltwater intrusion is forecast to exceed the Environmental Protection Agency’s standards for safe drinking water. The salty water in the public water supply also increases the risk of corrosion to machinery and appliances, such as washing machines, he added.
In a separate statement, Edwards said he was “optimistic” Biden would approve the emergency declaration, which would unlock federal aid for the affected communities.
What else is being done to help?
The United States Army Corps of Engineers is planning to bring 36 million gallons of fresh water daily into New Orleans on a barge next month as the expected saltwater intrusion from the Gulf of Mexico threatens the area’s drinking water supply.
It is also adding 25 feet of height to a 1,500-foot-wide underwater sill that was constructed in July to slow the saltwater’s progression up the Mississippi River. But the expansion won’t one completed for a few weeks and will only delay the intrusion by 10 to 15 days, Army Col. Cullen Jones told reporters.
Meanwhile, the Army Corps is also monitoring the location of the encroaching saltwater, which forms what’s known as a saltwater wedge as it moves up the river. As of last week, the wedge had toppled a sill at mile marker 63.8 near Alliance, La., just 23 miles south of New Orleans.
Edwards urged residents in New Orleans and the surrounding areas not to panic or rush to buy bottled water, saying that they will be notified in advance if the saltwater intrusion is imminent.
Big picture
Droughts are relatively common in Louisiana and throughout the southwest, but climate change is increasing the risk that they will occur more frequently, intensely, and for longer periods of time.
According to the National Oceanic and Atmospheric Administration, this tear has been the hottest on record for Louisiana.
“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,” Edwards said during a press conference Friday. “Unfortunately, we just haven’t had the relief from dry conditions, so that intrusion is worsening.”
