NEW ORLEANS (WVUE) – Along a stretch of the eastern shore of Plaquemines Parish, the Mississippi River offers a coastal project that coastal activists consider free.
In recent years, the river has burst its banks, turning a tiny channel into the equivalent of one of the top 10 largest rivers in the United States.
According to Corps hydrologists, Neptune Pass receives an estimated 16 percent of the Mississippi River’s water during flood periods.
Groups actively working to restore Louisiana’s coast argue that the river offers a virtually free diversion.
“A restored ecosystem is being created before our eyes for free,” said James Karst, communications and marketing director for the Coalition to Restore Coastal Louisiana.
They claim that Neptune Pass deposits sediment and creates new delta sections in both Denesse Bay and Quarantine Bay.
Not everyone is excited about the prospect of nature taking its new course.
Shipping stakeholders complain that the passage has already affected shipping because sandbanks have formed downstream on the slower-flowing river.
The Corps, which had originally planned to close the canal entirely, now plans to dual-use Neptune Pass.
The draft environmental impact assessment proposes a two-part approach to protect the integrity of the main riverbed: a rock sill at the bottom with a 100-foot-wide notch to reduce runoff from the river, and 20 V-shaped mounds to further reduce the velocity of water flowing into Quarantine Bay.
The Sediment Retention Enhancement Devices (SREDS), as they are called by the Corps, would be built from earth material, geotextile fabric and riprap.
“We created an opening to allow the river to flow and sediment to leave the river and settle in the bay in the receiving area,” said David Ramirez, a hydrologist with the Corps.
Critics of the river diversions wondered whether the new land created in the bays was simply land that had been displaced by the river over the years as the channel was widened.
While computer models suggest that about 70 percent of the new delta is due to displacement, the remaining 30 percent was created from sediment deposited by the river, according to Ramirez.
“The more wetlands there are between where we live and the Gulf of Mexico, the better our natural protection from hurricanes,” Karst said.
Commercial fishing interests complain that large amounts of freshwater flowing not only through Neptune Pass but also through other cuts on the east bank have dramatically changed salinity and destroyed the oyster crop.
“The report contains some innovative ideas, but many scientific questions remain unanswered,” said Alex Kolker, a coastal scientist at the Louisiana Universities Marine Consortium.
Kolker wants more details on how the proposal would affect the river’s flow, whether the SREDS would simply subside over time and how long the flow would be sufficient to develop land.
Under the Corps’ plan, Neptune Pass would accommodate six percent of the river’s flow.
“At the moment we do not have enough scientific evidence to make a comprehensive assessment of whether this will work or not,” Kolker said.
The Corps is accepting public comments on the proposal through the end of the month.
Subscribe to Fox 8 YouTube channel.
All rights reserved.
