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Two Studies Show Mississippi River Diversions Could Harm Marshland

For decades, those leading efforts to keep southeast Louisiana from being swallowed by the Gulf of Mexico have supported “Putting the river back into the marsh.” The thinking is that the river should be allowed to build new land, just as it had done for millennia before flooding was controlled. But what if pollutants in the river’s fresh water will kill the marsh before those sediments can do good?

Two recently released reports give that question new relevance.

1. A nine-year project in New England showed that fertilizer-based pollutants carried in the Mississippi River led to the collapse of salt marshes along Louisiana’s southeast coast.

2. A review of research on Louisiana’s freshwater diversions conducted by a panel of experts from outside the state concluded there was no evidence the projects would improve adjacent wetlands over the long term. The study suggested that the state’s Coastal Master Plan, built around large sediment diversions, should use a science-based approach, with ongoing monitoring and adjustments in diversion strategies as needed. For more information, contact

The reports provide new information for those who support other methods of coastal restoration and scientists recommending more research before river water is released into wetlands.

Related content on this topic available on the NCCOS website, The Lens, and FOX8 WVUE.


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