But the group’s identity was a surprise: The local chapter of the Sierra Club that greenest of environmental groups.In a letter to the state, John Dale Zach Lea, chairman of the chapter’s board, claimed the financial damage to oystermen and shrimpers caused by the river’s fresh water is unacceptable and unnecessary. Rather than divert river water and its marsh-building sediment load into the basin, the group says the state should build levees around a 14,000-acre area of the basin (the expanse of wetlands the diversion would resurrect) as a freshwater impoundment and leave the rest of Barataria Bay open to nature for oystermen and shrimpers. He claims that option would provide more flood protection without hurting commercial industries.