Ever since the Missippian and Ho-Chunk people settled in this area thousands of years ago, Madison’s lakes have drawn people from all over the world. Lake Mendota, the largest of Madison’s four glacial lakes, has been called the most studied lake in the world, thanks to the University of Wisconsin campus nestled on its southern shore. With all the volumes of books, reports and studies of Lake Mendota, it’s surprising there’s been relatively little written about Lake Mendota’s social history. Mariner, folklorist and former public television employee Don Sanford seeks to fill that void with the publication of his new book “On Fourth Lake: A Social History of Lake Mendota.”