This past Wednesday, November 12, 2014, the Louisiana Coastal Protection and Restoration Authority voted to send “River Reintroduction into Maurepas Swamp” as one of five projects to the RESTORE Council for “bucket 2” funding. Each RESTORE Council member can submit up to five projects until November 17, 2014.
This project, also known as the Maurepas diversion or the West Maurepas Diversion (and associated with Hope Canal early in its history), is designed to restore systems and processes that served the swamp before levees restrained the Mississippi River. The project has a long history in coastal restoration planning, starting with the The Louisiana Coastal Restoration Plan in 1993, the Louisiana Coast 2050 report in 1998, the Mississippi River Sediment, Nutrient and Freshwater Diversion Study in 1999, and both Coastal Master Plans in 2007 and 2012.
Studies show that 87% of Maurepas swamp is dying, largely due to nutrient deprivation, saltwater intrusion, and subsidence. Each of these stressors can be attributed to the swamp’s isolation from the Mississippi River. Since the swamp has been cut off from the Mississippi River for decades, the plants have been deprived of vital nutrients, and their growth and productivity has suffered. Saltwater is intruding from the Gulf of Mexico through Lake Pontchartrain, and therefore salinity is highest closest to Pass Manchac. Trees in the swamp on the edge of Lake Maurepas are dying of salt stress. Trees can withstand short saltwater intrusion events, and an influx of freshwater helps them recover. Areas that are touched by flowing freshwater have the lowest salinities. Healthy tree and roots systems help maintain soils, and fight subsidence. The highest bulk densities (a measurement of soil weight= dry weight of soil per unit volume of soil) are found in parts of the swamp with consistent freshwater input (low salinity), and lowest bulk densities occur at sites with high salinity.
A freshwater diversion from the Mississippi river can help fight each of these stressors, and maintain or even increase the health of the swamp. The diversion is designed to maximize “sheet flow” (the spread of water over a wide swath of the receiving area, or a “nonpoint” water source) which is important for improving water quality, increasing primary production, and decreasing salinities deep into the swamp. The total area expected to benefit from the reconnection to the Mississippi River will be 45,000 acres of wetland. Freshwater will help deliver nutrients to nutrient-starved trees at the interior of the swamp, and lower saltiness killing trees at the margin of Lake Maurepas.
The Louisiana Wildlife Federation and leaders in Ascension, St. James, and St. John the Baptist parishes expressed support for this project in the form of a sign on letter. You can read the letter here.
UPDATE: Thanks to all those who sent messages directly to the Coastal Protection and Restoration Authority to forward to the RESTORE Council with the project packet! View the projects submitted by CPRA for RESTORE Act Pot 2 possible selection. Check out all the projects submitted to RESTORE Council for consideration for pot 2 spending here.