MS River Saltwater Wedge Info for New Orleans and Southeastern Area

You may have seen news stories about the saltwater intrusion in the Mississippi River and the impact it may have on the water supply of communities upstream. The LRA Team, along with the Louisiana Dept. of Health (LDH) Engineering Team, is working to prepare members for the impact this could have on our residents and restaurants, should the situation worsen. The LDH in conjunction with the U.S. Army Corps of Engineers (Corps) are collaborating on communication and the construction of a higher underwater dam to stem the flow of salt water upriver.
 
Here are a few things to consider:
 

1. Saltwater Threat to Drinking Water: The Mississippi River is experiencing one of its lowest levels in recent history, and saltwater from the Gulf of Mexico could impact the processing of drinking water as far north as New Orleans' French Quarter.
2. Barrier Construction: The Corps has announced plans to enhance an existing underwater barrier to prevent the intrusion of saltwater further up the river. The current barrier “also called a sill” is expected to be overtopped by saltwater around September 22, potentially affecting Belle Chasse's drinking water by early October.
3. Current Impact: Due to saltwater intrusion, around 2,000 residents in Plaquemines Parish are relying on bottled water and other sources rather than their municipal system. The parish has distributed over 1.5 million gallons of water to affected residents.
4. Frequency of Saltwater Wedge: This phenomenon, known as a "saltwater wedge," typically occurs about once per decade, but 2023 marks the second consecutive year of low river flow due to drought, increasing the risk.
5. River Flow Predictions: Forecasts suggest that the river's flow could drop significantly by mid-October, making it challenging to push the saltwater back into the Gulf of Mexico.
6. Barrier Modification: The Corps plans to raise the current underwater barrier while creating a notch to allow ships to pass through. However, this plan is temporary as the real solution requires additional rainfall to alleviate the issue.
7. Alternative Solutions: The Corps is exploring the possibility of shipping freshwater from higher up the river to dilute the saltiness at affected water-treatment plants. Smaller treatment plants may also receive technology to remove salt and purify the water using reverse osmosis.
8. Health Precautions: Residents should not consume water compromised by seawater, as it can exacerbate some health problems like hypertension. There is also the possibility of damage to appliances that use water (washers, dishwashers, icemakers etc.) if they are exposed to corrosive saltwater.
9. Future Studies: The Corps is conducting a 5-year study of the lower Mississippi River to examine the effects of saltwater intrusion and ways to reduce its impact in the future. This study will be vital in developing strategies to mitigate the effects of climate change on the river and its communities.

 
Once the saltwater reaches the intake, it could be a few weeks before it could disrupt the water supply given the concentration of the water system’s chloride functions. This would not create a boil water advisory, as the issue with saltwater is not bacterial, but corrosion of plumbing systems, which may leach metals in the water supply.