Sea Grant-ers Pitch in for Habitat Planting in New Orleans

LSU Specialist Offers Insights into Recovery Since Hurricane Katrina

Stony Brook, NY, October 25, 2010 - Nearly two dozen Sea Grant communicators and colleagues from throughout the national network’s 32 programs recently participated in a habitat restoration planting effort in New Orleans' City Park. The group planted Spartina grasses – a rather common marsh grass with a very high salt tolerance – along 200 feet of shoreline in the brackish Big Lake, reinforcing the shore from erosion caused by wave action. The planting also created new fisheries habitat, maintained and stocked by the Louisiana State Department of Wildlife and Fisheries.

“We have a lot of salinity issues in this part of the country, so we’re always trying to figure out what will stay in place once we get it in there,” said Caitlin Reilly, a Sea Grant extension specialist at Louisiana State University (LSU) who led the group.

In addition to overseeing planting efforts in City Park, Reilly continues to focus efforts in other areas of the southeast region of Louisiana. Since this past June, Caitlin has coordinated the LSU Ag Center's Oil Spill Extension Response and Recovery Task Force as a Louisiana Sea Grant Extension Associate. Reilly, a native New Yorker and graduate of Manhattan College, also manages a Wetland Plant Center in New Orleans.

Last month, Reilly visited New York Sea Grant staff at Stony Brook University and, during her lecture there, shared some valuable lessons learned from her experiences with the aftermath of the Deepwater Horizon oil spill and with on-the-ground issues of coastal land loss.

More on the planting and region, post-Katrina

During the planting, Reilly pointed out areas in the Park where marsh grass plantings from the last year have been very successful. About 55 volunteer hours went into this portion of Reilly’s on-going project, for which she supplied the necessary plants and divets (digging instruments). Reilly also provided the volunteers with some background on the marsh area, which has been impacted by both natural and human forces. “In the face of land loss, we see a lot of need for restoration in Louisiana, especially after Hurricane Katrina.”

Lake Pontchartrain is part of the area’s estuary system north of New Orleans, which also includes Lakes Borgne and Saint Catherine. These spots, along with the eastern side of the city of New Orleans, are where much of the storm surge swept into New Orleans during Hurricane Katrina.

“New Orleans is in a bowl, so the [Mississippi] River is actually where the high ground is,” Reilly emphasized.  “So, when Katrina was happening, you could actually still walk along the River. They called it ‘The Isle of Denial” or ‘The Sliver By the River.’ There are also some ridges near the bayou that are high ground that didn’t flood.”

Historically, it was flooding from the Mississippi River that was the issue of concern. But, with all the modifications to the River’s hydrology in the last 100 years, “it’s changed to where we don’t have as much protection against hurricane storm surges,” said Reilly.

In the French Quarter, you might have seen some short-term flooding of rainwater. But, all of that went down really fast. “The real problems came from sitting water over time,” said Reilly. “So, there was minimal damage to the French Quarter and right along the [Mississippi] River. It was in the areas closer to where the levees breached throughout southeast Louisiana and Mississippi that the main thrust of damage occurred.”

In this region, there are two levee systems – there is the system of levees that controls the Mississippi River and another for all the drainage systems that serve as a hurricane-protection measure. The levee system on the River is what built the foot of south Louisiana that sticks out into the Gulf. Over the last 10,000 years or so, the River has moved back and forth, spreading out sediment and building land. “At this point, with all the modifications we made to the area’s hydrology, we really don’t see a lot of River flooding,” said Reilly. “And that’s considered to be part of the problem with sinking here. We have this long-term issue of sinking and then we have all these canals which have helped speed up the process of erosion.”

There is active building happening in some areas of southern Lousiana and subsidence in others. After the Great Mississippi River flood in 1927, legislation was passed that empowered the Army Corps of Engineers to levee the entire Mississippi River, which is basically the main drainage system for the entire United States. From the Colorado Rockies to the Appalachian Mountains, everything drains into the various rivers that then drain into the Mississippi River.

And, when you combine this shift in water diversion with both a system of up-river dams that prevent sediment from flowing down and cuts through the area’s hydrology due to canal explorations for oil and gas that are slowly filtering out salt, Reilly cautioned, “all of a sudden, you have tidal motion in areas like swamps that should instead have a graduated salinity. So, we’re seeing large die-offs in our swamps which should be mostly freshwater.”

Lasting Effects of Hurricane Flooding

Hurricane flooding in the modern era has been contributed to largely by die-offs of areas like the Cyprus Triangle, near the Ninth Ward, which is located in the easternmost downriver portion of the city of New Orleans. Such locales never recovered after the opening of the Mississippi River limited sediment transport to keep plants and grasses in place. This move also prevented freshwater from flushing out the land after flooding from severe storms like 1965’s Hurricane Betsy, which left considerable salt staining. All this has caused not only more flooding, but sinking as well.

“This land has been sliced and diced, with nothing to help build the land back up,” said Reilly. “So, there are a good number of dedicated dredging and restoration projects that continue to this day to help combat these issues.”

Special thanks to Lousiana Sea Grant’s Paula Ouder for recording the discussion portion of the Service Project. And for some of the pictures here, provided by Sea Grant Programs in Louisiana and Virgina.

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