In a significant stride towards protecting the region’s drinking water, a remarkable engineering feat has been accomplished as a dredging company finalized the construction of an underwater sill beneath the Mississippi River, according to this article from Nola.com. This massive structure, located at Myrtle Grove, will play a crucial role in safeguarding the public and industrial water supplies of upper Plaquemines and St. Bernard parishes, as well as the city of New Orleans, by blocking the intrusion of saltwater from the Gulf of Mexico.

Weeks Marine Inc., a New Jersey-based company, commenced dredging operations from an area on the right descending side of the river just upstream on July 11 and 12. Their J.S. Chatry cutterhead dredge, along with a fleet of smaller boats, worked tirelessly to maintain a surface and underwater pipeline for disposing of sediment on the river bottom. The Defense Department recognized the significance of this endeavor and awarded Weeks Marine’s Covington office an $8.9 million addition to their existing river dredging contract to finance the construction of this crucial dam for the protection of the regions drinking water.

To ensure unimpeded passage for ocean-going vessels, the sill was strategically designed to be 55 feet below the surface, while the river itself reaches a depth of about 90 feet at the dam’s location. This engineering marvel is situated at mile marker 63.7 above Head of Passes. The project faced challenges, and during the dredging operations, the U.S. Coast Guard implemented one-way traffic rules for a two-mile stretch along the river.

The urgency of this endeavor arose due to the recent retreat of saltwater, which had reached mile marker 52, thanks to heavy upriver rainfall over the past three weeks. However, there’s optimism in the forecasts from the National Weather Service’s Lower Mississippi River Forecast Center, which predicts that water levels in the lower stretch of the river will continue to fall over the next 28 days. This bodes well for maintaining the integrity of the dam.

Despite these promising developments, the current water crisis in Plaquemines Parish still persists. Saltwater contamination remains an issue, affecting the water intake for the Boothville water treatment plant. To address this, the parish is actively distributing bottled water and ice to residents, mitigating the hardships caused by the contaminated supply.

Furthermore, the parish is working on multiple fronts to find solutions. A booster pump is under construction to facilitate the flow of water from the Belle Chasse water plant to Venice. However, this project encountered delays due to manufacturing and parts shortages, but it is expected to be completed during the week of August 14. Additionally, the Port Sulphur water treatment plant is undergoing repair work, and the parish is collaborating with the Corps to procure reverse osmosis equipment that will help remove saltwater at the Boothville and East Pointe a la Hache water plants.

The completion of the underwater dam comes as a significant relief for the region, as it now stands as a powerful shield, protecting the water intakes of crucial plants and industries along the river. However, it’s essential to understand that this is not a permanent solution. When the river experiences higher water levels and faster flow rates later in the year, saltwater may be pushed back towards the Gulf, and the dam could face erosion. Therefore, continuous monitoring and maintenance will be vital to ensure its long-term effectiveness.

In conclusion, the completion of the Mississippi River underwater dam marks a momentous occasion for Louisiana and its efforts to protect its vital drinking water sources. This achievement represents the collaboration of engineering expertise, government support, and a commitment to the well-being of the communities relying on this waterway. While challenges still lie ahead, the completion of the dam stands as a testament to the resilience and determination of Louisiana’s people in safeguarding their environment and resources for generations to come.

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