Mississippi River’s newest distributary: Mardi Gras Pass gets a tour
At just five months old, Mardi Gras Pass is the newest distributary of the Mississippi River — a modern addition to an ancient system. Located about 50 miles south of New Orleans on the east bank of the river, the pass was discovered by Lake Pontchartrain Basin Foundation (LPBF) staff on Mardi Gras Day 2012. The natural flow of the Mississippi River had cut a continuous channel through the river’s bank and into the Bohemia Spillway, creating a new distributary and offering a small glimpse at what a natural delta system looks like.
On August 1, Louisiana’s Governor’s Coastal Advisory Commission held their regular meeting in Davant in Plaquemines Parish. At the meeting, Dr. John Lopez, executive director and coastal sustainability program director for LPBF, presented on the status of Mardi Gras Pass to the commission. The presentation showcased how LPBF and its partners were taking every advantage to study and learn about the river’s natural ability to connect to the wetlands. In June, LPBF released a report on the dimensions of the new channel, and its staff continues to regularly monitor the pass’s progress. Both the report and Dr. Lopez’s presentation can be found at SaveOurLake.org.
Mardi Gras Pass’s flow has increased modestly since February, but the discharge is almost entirely dependent on the height of the Mississippi River water level. This summer, while the river has been exceptionally low, the flow rate has been less than 500 cubic feet per second. But when the river rises toward the end of the year, the flow could be ten times greater.
The Governor’s Commission also visited Bohemia Spillway and Mardi Gras Pass themselves. They were taken to a location where the newly-established Mardi Gras Pass has cut through a private road within the spillway, making it impassable. A local oil company has applied for a permit to repair the road, which could close off the flow from the river and block the pass. The state has expressed scientific interest in Mardi Gras Pass and recognizes it as a potential restoration opportunity. Therefore, the state has requested that the company evaluate alternatives to repairing the road which would allow the pass to still function.
The Commission also visited the actual location where Mardi Gras Pass has cut through the Mississippi River’s bank. Some Commission members had never seen the Mississippi River without an artificial river levee, and it was a moving experience to see the river in its natural condition and to see the meandering Mardi Gras Pass’s channel cutting through the river’s willow tree forested bank. Mardi Gras Pass is a real-life example of nature at work. As a natural distributary and natural diversion, Mardi Gras Pass represents a small precursor to what a more natural Mississippi River and delta could look like in a Coastal Master Plan future.
- Presentation to Governor’s Commission: Status of Mardi Gras Pass, the Newest Distributary Pass of the Mississippi River within the Bohemia Spillway, Southeast Louisiana (Lake Pontchartrain Basin Foundation)