Drought sparks drinking water concerns as saltwater creeps up Mississippi River
NEW ORLEANS — Drought across the midwestern and southern U.S. has left the Mississippi River with such low water levels that saltwater from the Gulf of Mexico is creeping upriver in Louisiana, which could impact the drinking water of thousands of residents in the next few weeks.
For those who rely on the Mississippi River for drinking water, the saltwater intrusion is a potential health risk, as high concentrations of salt in drinking water may cause people to develop increased blood pressure and corrode drinking water infrastructure.
Officials are expected to give an update on the situation later Friday.
The saltwater has already entered the drinking water of communities south of New Orleans – from Empire Bridge to Venice – making the water undrinkable for about 2,000 residents and causing water outages at local schools. As the saltwater moves upriver, it could impact the drinking water for another 20,000 people in Belle Chasse. After that it could reach the drinking water intake for the New Orleans community of Algiers, across the river from the French Quarter.
With no significant rain in the forecast, experts warn the saltwater could reach parts of New Orleans by Oct. 10, said Matt Roe, a spokesperson for the U.S. Army Corps of Engineers, New Orleans district. “The 28-day river forecast coupled with the rain is just not enough to make a major impact on the river down here,” he said.
At 3 p.m Central, the Louisiana Governor’s Office of Homeland Security and Emergency Preparedness is expected to hold a press conference at the Morial Convention Center in New Orleans, where a website will be announced that will have centralized information about how local water systems are being impacted.
To slow the progression of the saltwater, the Army Corps of Engineers constructed an underwater barrier in downriver from New Orleans in July, Roe said. The mouth of the Mississippi River is below sea level. Because saltwater is denser than freshwater it is moving underneath the freshwater along the bottom of the river in a wedge shape.
The barrier was intended to slow the upstream movement of the saltwater, but the salt wedge has overtopped the barrier. Similar barriers were constructed in 1988, 2012 and 2022. This is the first time the barrier has needed to be built in back-to-back years. Last year, the barrier wasn’t overtopped, he added.
The Corps of Engineers is now building the underwater barrier higher near the banks of the river but will not raise the barrier in the middle of the river to prevent blocking ship traffic. “Our estimates say that adds about 10 to 15 days delay of saltwater progressing up river to allow the city to work on their mitigation plans,” Roe said.
Communities along the river are keeping a close eye on the upstream movement of the saltwater wedge and testing the salinity levels near their water system intakes, said Dr Joseph Kanter, state health officer and medical director for the Louisiana Department of Health. “Everyone along the river knows where the wedge is and when it’s approaching. That’s not going to be a surprise,” he said.
While salt is not a federally regulated contaminant, it could be a health concern for people who are on low salt diets and for those who are pregnant. The World Health Organization’s drinking water guideline suggests that 200mg of sodium a liter is the threshold at which most people will not want to drink the water because of taste. When saltwater is pumped through a water distribution system it can cause pipes to corrode, potentially leaching heavy metals from the pipes and pipe fittings into drinking water.
But it is difficult to predict which metals might leach from pipes, as distribution systems are all different and some do not have full maps of their systems. “So, a hallmark of the response is going to be frequent testing of the water that is going through the water systems distribution network,” Kanter said.