Mark Schleifstein, Times-Picayune/The Advocate

A new study of the dramatic loss of wetlands in the Barataria Basin south of New Orleans during the last 130 years concludes that the two main causes have been construction of levees along the Mississippi River and subsidence due to oil and gas activity.But the study also contains potential good news: There may be enough sediment in the river to rebuild coastal land, disputing earlier estimates.