Maurepas diversion proposed to lessen environmental impacts of West Shore Levee

Published 12:00 pm Friday, April 22, 2022

LAPLACE — The public is invited to provide input on a proposed freshwater diversion from the Mississippi River to the Maurepas Swamp intended to lessen the environmental impacts of the West Shore Lake Pontchartrain Levee Project.

According to the latest design updates, construction of the West Shore Levee Project could impact up to 10,892 acres of swamp in the Louisiana coastal zone. The proposed 2,000 cubic feet per second freshwater diversion would replace the functions of impacted swamp habitats.

The diversion is expected to operate for six months out of the year, likely between January 1 and July 1, to strategically deliver nutrient-laden water to the impacted swamplands.

The first three years of operation would consist of a ramp-up period of gradually increasing flow duration and magnitude. According to a Supplemental Environmental Impact Statement released for public review this month, the ramp-up period aims to reduce the initial shock to the system and enable adaptive management.

The diversion would satisfy the mitigation requirements incurred by not only the West Shore Lake Pontchartrain Levee Project, but also the Comite River Diversion Project and the East Baton Rouge Parish Watershed Flood Risk Management Project. Funded through the Bipartisan Budget Act of 2018, these three projects impact similar habitats within the same watershed.

The annual maintenance costs are estimated at $7,073,512. After construction is complete, the Coastal Protection and Restoration Authority Board of Louisiana would assume operation and maintenance, repair, replacement and rehabilitation of the project. The cost of operation has been conservatively estimated at $105,000 per year, based on the salary of a full-time CRPA employee.

Public scoping meetings regarding the Supplemental Environmental Impact Statement were conducted virtually on October 5 and 6, 2021. During the public comment period, 70 responses were received via Facebook and email.

Several comments supported the diversion, stating that the restored habitat would protect local communities as “a critical line of defense for storm surge.” The public was also in favor of restoring critical fish and wildlife habitats that could provide economic benefit through recreation.

Several commenters expressed concerns over potential delays the diversion could pose to the West Shore Levee construction.

The U.S. Army Corps of Engineers New Orleans District released updated environmental documents for public review on March 18, 2022, but these documents were withdrawn for revision on April 1 after outdated information was identified.

The documents were re-released on April 15, 2022. Additional virtual public meetings will be held to provide information and receive public comments.

All comments must be received by May 31, 2022 and should be submitted to:

Mr. Landon Parr

U.S. Army Corps of Engineers

Environmental Planning Branch

Regional Planning and Environmental Division South, CEMVN- PDC-C

7400 Leake Ave, New Orleans, LA 70118

Comments may also be submitted via email to mvnenvironmental@usace.army.mil.

An additional $453 million was allocated to the West Shore Lake Pontchartrain levee project in January 2022 to cover the costs of inflation and extra resiliency features, bringing the total federal investment to more than $1.2 billion.

The groundbreaking for construction of the West Shore Levee Project took place in July 2021. The project spans 18.5 miles, which includes 17.5 miles of levees, one mile of T-wall, drainage structures, pump stations and several non-structural protection measures to form an integrated protection system.

Work is currently underway on access road construction, sand stockpiling and test section construction. For more information, visit www.mvn.usace.army.mil/About/Projects/BBA-2018/West-Shore-Lake-Pontchartrain