PLAQUEMINES PARISH, Louisiana — Twenty years after Hurricane Katrina, the cancellation of a $3 billion wetland restoration project has upended a hard-won consensus about how to rebuild this state’s rapidly eroding coast and shield the New Orleans area from future storms.
Engineers and scientists for decades have studied the erosion of Louisiana’s coastal wetlands, which are disappearing into open water at a faster pace than anywhere else in the nation. The devastation wrought by Katrina forced state leaders to get serious about the problem and craft a 50-year strategy featuring an ambitious plan to harness mud and sand carried by the Mississippi River to build new land.
The idea was simple: To help protect New Orleans and other Gulf Coast communities, Louisiana must restore the natural protection offered by wetlands that slow down hurricanes and absorb storm surge…