Lower Miss. cuts new pass
Scientists saw something new happen to the lower Mississippi River on Mardi Gras Day — the birth of a new Mississippi River pass.
“This type of thing has not happened in modern times,” said John Lopez, executive director of the Lake Pontchartrain Basin Foundation. “And it indicates the river is going through dynamic changes.”
The new pass could provide information on how the river naturally wants to divert its flow and could be instructive in designing the many diversions the state included in the coastal restoration master plan, he said.
The state also could save some money if it can use this new pass to replace one or both nearby diversion canals included in the state master plan for coastal development.
However, the river is flowing through a road that supplies an oil and gas facility called Eland/Sundown Energy and there is currently a permit application to rebuild that road, which would cut off the flow of water.
Karl Morgan, administrator of the state Department of Natural Resources’ permits and mitigation division, said the U.S. Army Corps of Engineers approved a “programmatic general permit” earlier this year. With that type of permit approval, he said, the corps agrees with whatever the state DNR decides to do with the permit.
Although the permit asks to rebuild the road in two places where it washed out during the 2011 flood, DNR has received objections to closing off the newly formed channel. In addition, the state master plan for coastal restoration includes two planned diversions to be built near that site, so that created a need to ask for more information, Morgan said.
“We asked them (the oil company) to look for alternatives, so we’re waiting for that,” Morgan said. “We’re looking for something that would allow the water to pass.”
When the company provides that alternative road design, Morgan said, staff will see if it meets a variety of conditions, including if it’s the least damaging alternative and how it meshes with the state master plan for coastal restoration.
“There is a diversion there. We’ve talked to CPRA (Coastal Protection and Restoration Authority) and the effect of the diversion is a good thing and it’s part of the master plan,” Morgan said. “It’s one of the primary reasons we’re asking for alternatives.”
If the company doesn’t come back with an alternative, the company will have to justify why it couldn’t do something else, Morgan said.
“We feel there could be other alternatives,” he said.
The pass was discovered through the course of a study being done by the Lake Pontchartrain Basin Foundation on how water from the Mississippi River flows through the spillway, located about 50 miles south of New Orleans.
The spillway has allowed river water to flow to the marshes east of the river for more than 80 years since the levees were knocked down in 1926 because of concerns of increasing flood levels at New Orleans.
Scientists with the foundation noticed during the 2011 flood that a new channel was making its way toward the river and on Mardi Gras Day 2012 those scientists saw the channel and the river meet, creating a new pass.
This “Mardi Gras Pass” is about 44 miles upstream from the Head of Passes, according to information from the Lake Pontchartrain Basin Foundation.
Lopez said limiting the flow of the pass through the use of culverts under the road would limit the ability to monitor how this pass would evolve over time, and it would limit the amount of water that could flow through the channel to the size of the culverts.
Lopez also said the two planned diversions in the state coastal master plan are just a few miles south of this site — the Lower Breton Diversion could cost $220 million and the Bohemia Mississippi River Reintroduction project that could cost between $10 million to $20 million.
Garret Graves, director of the Louisiana Governor’s Office of Coastal Activities, said the road in question was washed out in 2006, 2008 and again last year, so rebuilding the same design doesn’t seem sustainable, he said.
At the same time, experiences elsewhere along the coast show that uncontrolled diversions aren’t sustainable and can create other problems, such as with navigation.
“We’re going to have some kind of control on this thing,” Graves said of the Mardi Gras Pass.
While discussions are continuing about possible alternatives for the road, the state also is looking at the possibility of moving the planned Lower Breton Diversion project up the priority list for possible location at the Mardi Gras Pass site.
Nothing’s been decided, Graves said, but the state is looking at how it might maximize the new pass location and save some money.