On March 26, the draft of the 2012 Coastal Master Plan arrives in the Louisiana Legislature to begin its approval process. In part one of our special report “Coastal Master Plan 101,” we examined the process that created the draft which will soon be in the hands of the legislature. Today, we will take a closer look at what’s in the plan and how it relates to the different areas of Louisiana’s coast. Keep in mind that time comes into play with regard to the Coastal Master Plan. This is a strategy which reaches 50 years into the future, and the master plan separates projects among short term and long term implementation. So, for each region of the coast, there are two suites of projects: those intended for the next 20 years, and those which come into effect in the 30 years following.
Within the Master Plan, the Coastal Protection and Restoration Authority of Louisiana (CPRA) divides the Louisiana coast into three sections: the Chenier Coast covering the Southwest coast, the Deltaic Plain in the Southeast, and the Central Coast, which bridges those two zones. Each zone requires a different strategic approach.
The Southwest is the Chenier Coast, which stretches from the Sabine Pass to Vermilion Bay. Lake Charles and Cameron Parish are of strategic importance to this particular coastal zone, and protecting this vital industrial and economic area is a priority of the 2012 Coastal Master Plan.
CPRA believes shoreline stabilization and salinity control to be the most important tactics to use along the Chenier Coast. The Master Plan will implement projects that control saltwater intrusion into the interior marshes through the restoration of natural ridges and stabilization of waterways that are currently serving as conduits for saltwater. The Master Plan calls for the use of salinity control structures, bank stabilization of the Gulf Intracoastal Waterway, and marsh buffers to slow the steady influx of saltwater into the interior of this zone. The state also intends on providing 500 year flood protection to Lake Charles, although the specific projects and design for that protection are anticipated to undergo continued refinement over the next several years. This protection could be in the form of a ring levee, or a combination of restoration features.
The Central Coast stretches from the Eastern-most tip of Vermilion Parish to Lafourche Parish’s eastern border with Jefferson Parish. The extreme western boundary of this zone, including parts of Vermilion, Iberia and St. Mary Parishes, requires shoreline protection and oyster barrier reefs to protect the bays there. The Atchafalaya Delta, as well as the Wax Lake Delta, are actually gaining land through the deposition of sediment from the Atchafalaya River. The state plans to take advantage of this process by diverting freshwater and sediment eastward into the Terrebonne marshes. Not all of Terrebonne’s marshes will benefit, however. The land loss in Terrebonne Parish is profound in certain areas because some places in this zone no longer have access to the fresh water and sediment of the Mississippi River and its distributaries. This area has proved somewhat problematic for the state. In particular, those areas with rapid subsidence rates, but no immediate source of freshwater and sediment will rely on structural protection, natural ridge restoration, and barrier island restoration.
Populations in this area receiving levee structural protection based on their densities include Franklin, New Iberia, Morgan City, and Houma and nearby bayou communities.
Southeast: Deltaic Plain
In the Southeast, the Mighty Mississippi and its tributaries played a powerful role in depositing layers of sediment, forming deltas and building our coast as the river shifted its course to find steeper and shorter pathways to the Gulf. Over the years, the policy of confining the river to its existing channel for purposes of flood control and navigation decreased the amount of fresh water and sediment pouring into interior swamps and coastal marshes, as well as extended a fortified navigation route further and further into the Gulf. This sediment no longer reaches the basins on the east and west sides of the Mississippi River, nor does it nourish coastal marshes. The rich sediment instead flows into the Gulf of Mexico, lost to all good purpose.
The solution for the Southeast Zone relies on major river diversions reconnecting the river to adjacent marshes in Breton Sound and Barataria Basin. Marsh creation will also be used at the mouth of Lake Pontchartrain and in areas around Lake Borgne and Biloxi marsh to protect against the Gulf. New Orleans and surrounding communities will also receive 500 year flood protection, as befits the area’s important economic and cultural status. Additionally, restoration of natural ridges and barrier islands will continue in a chain eastward from the Central Coast to the Mississippi River.
Looking Ahead to Tomorrow:
In part three of Coastal Master Plan 101, CRCL weighs in on what we as an organization think of the 2012 Coastal Master Plan, how it was composed, and how it addresses coastal land loss in Louisiana.
Be sure to check out the official draft of the 2012 Coastal Master Plan. It’s available as a free download from the CPRA website, (here).