Saltwater intrusion and its potential impact on drinking water
The U.S. Army Corps of Engineers has implemented an underwater barrier in an effort to combat saltwater intrusion in the Mississippi River. This barrier is intended to prevent saltwater from contaminating the freshwater supply that serves several communities in Louisiana. However, it has prompted concerns about the timeline of saltwater intrusion and its potential impact on drinking water.
On Friday, the corps provided an updated timeline, taking into account the barrier's installation. According to this revised schedule, the saltwater is not expected to reach the Belle Chasse drinking water intake until October 13th, with the Algiers intake facing potential intrusion around October 22nd.
Louisiana Governor John Bel Edwards has been actively involved in addressing the situation and coordinating efforts with the affected parishes. He shared his concern regarding the delay and the urgent need for rain further upstream in the Ohio Valley. While forecasts predict above-average precipitation in the upcoming winter months, immediate relief is essential.
Colonel Cullen Jones of the U.S. Army Corps of Engineers emphasized the scale of rainfall required to address the issue effectively. A substantial 10 inches of rain across the entire Mississippi Valley would be necessary to raise the river's flow sufficiently to push back the encroaching seawater.
The challenge stems from the fact that the mouth of the Mississippi River lies below sea level. Due to the density difference between saltwater and freshwater, the saltwater infiltrates beneath the freshwater, creating a wedge-shaped intrusion along the riverbed.
Historically, the lowest recorded levels of the Mississippi River were noted in 1988. During that period, seawater briefly entered the water systems of New Orleans before being displaced by freshwater. Current projections suggest that the current low river levels could persist for an extended period, potentially exposing the system to saltwater for weeks to months.