The final decision on whether to start building the first river diversion in the state’s coastal restoration effort is set to be made Oct. 21.

Kyle Graham, head of the state’s Coastal Protection and Restoration Authority, said his agency’s governing board will decide that day whether to build or cancel the Mid-Barataria Diversion near Myrtle Grove, the first of five such projects on the lower river in the current Coastal Master Plan.

Diversions have long been the centerpiece of coastal restoration plans because the river carries the sediment needed to fill the sinking basins along the coast. But they recently have become the most controversial among some fishers who fear the influx of fresh water could displace target species such as brown shrimp, oysters, speckled trout and redfish.

The fishers support the alternative of pumping dredged sediment from the river into the sinking wetlands, a process that would not dramatically lower salinity levels. While faster at building land and initially less expensive, the dredge-and-fill projects have to be repeated in 30 years. And they become more expensive as the projects move farther from the river. Diversions, while much more expensive to construct and build land more slowly, become more cost-effective over decades because they can build land as long as the river flows.

Research has shown the Myrtle Grove diversion could build as much as 22 square miles of wetlands in the rapidly subsiding wetlands on the northeastern side of Barataria Bay in 20 years. And the results of new research on the river indicates there is enough sediment to accomplish most of the master plan goals.

With the decision on Myrtle Grove just three weeks away, Graham said his agency is still evaluating the results of a suite of studies on the project’s costs and benefits. Those include computer modeling that predicts the benefits of the wetlands the diversion could rebuild and save compared to costs of the social and economic disruption that project might cause.

Graham has said if the studies showed the costs outweighed the benefits of the long-planned project, his agency would recommend canceling it.

“I actually have a series of meetings later this week and a bunch next week where we’ll be wrapping our hands around all the studies we’ve been doing,” he said. “But we [on the CPRA staff] plan to have a recommendation on the path forward for Myrtle Grove in time for the next board meeting.”

Graham stressed that Myrtle Grove will be the only diversion decision made because it’s the only one with funding and has completed engineering and design studies. The money comes from the criminal settlement in the Deepwater Horizon disaster.

Bob Marshall

From 2013 to 2017, Bob Marshall covered environmental issues for The Lens, with a special focus on coastal restoration and wetlands. While at The Times-Picayune, his work chronicling the people, stories...