The Louisiana Coastal Master Plan, as it's called, is a moonshot bet, the state's last best chance to slow the self-destruction caused by three centuries of human intervention on the environment. First, beginning in 1717, when the French built levees to protect New Orleans, came the channelization of the Mississippi River behind levees and dams. In preventing floods, it also starved the communities and wetlands of southern Louisiana of the rich, land-building river sediment that once kept the whole spongy region from naturally sinking into the Gulf.                                                                                                                                                                                                                                                                                                                                               Next, in the 20th century, came the oil and gas industry, which sliced the wetlands to pieces with canals that provided the sea more paths to surge inland. And now comes climate change, which is raising sea level and intensifying hurricanes-and thus accelerating the loss of land to the sea.  Bren Haase oversees the 50 billion plan, The Louisiana Coastal Master Plan as it's called. It's the state's last best chance to slow the self-destruction caused by three centuries of human intervention in the environment, and hopefully keep the state's coastline from disappearing off the map.                                                                                                                                                                                                                                                                      Haase directs the Coastal Protection and Restoration Authority (CPRA)-formed in 2005 in response to damage done that year by hurricanes Katrina and Rita. It saw a $13 billion windfall from settlements after the 2010 British Patrolium oil spill. It's using that money to dredge sand offshore and pump it toward the coast to rebuild a network of disappearing barrier islands. The fresh mud from the Mississippi River is expected to rebuild tens of thousands of acres of coastal marshes, keeping the bays from becoming ocean.                                                                                                                                                                                                                                                                                                                                                                   In the 16 years since the CPRA kicked into gear, 60 miles of barrier islands and berms have been constructed, 365 miles of levees improved, and 54,403 acres of wetlands revived. These days, other U.S. states and cities are discussing ambitious coastal restoration plans too. But none has yet been able to move forward as Louisiana has. Houston, Miami, and Boston have all considered plans for major storm barriers, but so far have not begun to execute them.                                                                                                                                                                                                                                                                                                                                                                                                                                                                       In 2017 the plan was approved unanimously by the state's legislature. The Mid-Breton diversion, on the east side of Mississippi, could build almost 16,000 acres of new wetland over a 50-year period in Breton Sound, creating wildlife habitat and storm protection for New Orleans and other cities. "The Mid-Barataria division, on the west side, would divert up to 15 percent of the river at times of high flow, typically in winter and spring.  It would create up to 30,000 acres of land in Barataria Bay over 50 years.                                                                                                                                                                                                                                                                                                                                                                                            Nothing can build back land like the river itself, Haase says:  "We believe we can use the power of that river to mimic the process that built southern Louisiana in the first place," but rebuilding what once was inevitably means changing what's there now.