A major “water wars” trial between Georgia and Florida is set to start Monday on Halloween — interesting timing, as the issue of water sharing has haunted the two states, as well as Alabama, for more than two decades. The latest court battle, taking place in Portland, Maine, could be a significant milestone, observers of the exhaustive conflict said in interviews last week. “I think this is, in large part, probably the end game ... for Florida in terms of trying to secure more water for itself out of the ACF,” said Clyde Morris, lawyer for the Gainesville-based Lake Lanier Association.