Diverting The Mississippi River To Save The Louisiana Coast

In a lush green bayou a little southeast of New Orleans, John Lopez and Howard Callahan are cruising the waterways in an airboat under the hot Louisiana sun on a recent day.

It’s an area known as Breton Basin, and Callahan is a local land manager who often helps researchers such as Lopez explore environmental changes in coastal wetlands. The pair head to a concrete and steel structure that separates the bayou from the nearby Mississippi River.

This is the Caernarvon river diversion. Built in 1991, it works like a faucet: When it’s open, freshwater and sediment from the Mississippi River — usually hemmed in by the levee system — flow back into what was a dying swamp. Diversions such as this one are meant to free the river to do its original job as it nears the Gulf of Mexico: spread out sediment, create land and provide freshwater to local habitats.

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