Global Courant
Officials in Louisiana are in a race against time as salty water from the Gulf of Mexico threatens drinking water supplies in New Orleans and surrounding areas due to unusually low levels in the drought-stricken Mississippi River.
New Orleans Mayor LaToya Cantrell signed an emergency declaration Friday following concerns that saltwater intruding upstream could impact the availability of safe drinking water in the coming weeks.
The situation highlights the dangers of salt water ingress for communities in the southeastern part of Louisiana and contributes to broader concerns about climate change and the availability of safe drinking water in drought-prone parts of the country.
Stephen Murphy, an assistant professor at Tulane University’s School of Public Health and Tropical Medicine, estimated that nearly 1 million people in the New Orleans metropolitan area could be affected if water levels in the Mississippi River remain low.
Although forecasts are subject to change, it is estimated that the salt water could reach the Belle Chasse water intake facilities on October 13 and the New Orleans facilities later in October.
About 2,000 residents of Plaquemines Parish, south of New Orleans, already were relying on bottled water this summer after salt water infiltrated the area’s water systems.
Too much salt in drinking water can cause increased sodium levels in the body, causing blood pressure to rise.
Persistent drought have kept the Mississippi River at abnormally low levels and significantly weakened its flow, Murphy said, adding that the area’s unique topography has worsened the situation.
The mouth of the Mississippi River is significantly below sea level, meaning some of the salty water from the Gulf of Mexico naturally creeps inland. Salt water is more dense than fresh water and therefore flows like a wedge along the riverbed beneath the fresh water of the Mississippi.
In normal times, the river’s downstream current is strong enough to hold back the advancing salt water, preventing it from flowing too far inland. Severe drought has caused water levels in the Mississippi to drop to some of the lowest levels in recent decades.
“The river flow rate is no longer able to combat the saltwater wedge,” Murphy said. “On a normal day it’s strong enough to keep the saltwater at bay, but we’ve just seen a reduced amount of water coming this far south downstream.”
Scientists have said saltwater intrusion into the Lower Mississippi River area becomes a problem when the river’s flow rate drops below 300,000 cubic feet per second. Last week, Murphy said, the flow was 148,000 cubic feet per second.
During a news briefing Friday, Louisiana Governor John Bel Edwards said the lack of precipitation is to blame for the river’s woes.
He said this in a statement released Friday: “Unfortunately, without any relief from the dry weather, we are beginning to see saltwater intrusion creep further up the river, despite efforts to mitigate the Army Corps of Engineers’ concerns.”
This week, the Army Corps is expanding an underwater barrier first built in July to slow saltwater intrusion upstream. The barrier, also called a sill, functions in the same way as an underwater dike. Murphy said if conditions remain dry, the threshold will most likely be exceeded again.
“We’re doing our best to delay the onset of this saltwater wedge moving further north and wait for Mother Nature to hopefully intervene, but also to help us get some resources and resources to capture some of that saltwater to compensate,” he said.
State officials said they will work with parishes to test water supplies and monitor any changes. The Army Corps also said millions of gallons of water are being brought in to dilute the local water supply if necessary.
“The Corps is in the process of securing water barges that will support the affected water treatment plants by transporting water collected from portions of the river where salinity measurements have not been taken,” said Col. Cullen Jones, commander of the Corps’ New Orleans District. said in a statement Monday. “This water can then be combined with water from the municipal facility to create a mixture that is safe for treatment.”
Murphy said concerns about drinking water in the region are part of a larger story about drought and the availability of drinking water in a warming world.
“It’s something we can no longer ignore,” he said. “We’ve had an extremely hot season, we’ve had a heat dome in the southern states and we’ve been experiencing warmer than average temperatures around the world. It’s a shame, but sometimes it takes a moment of crisis to draw attention to this. things in our own backyard.”
