A Decatur, Alabama, man apparently drown in Big Blue Lake in Mason City yesterday. Rescuers were called to Lester Milligan Park shortly before five o’clock last night after Mason City police received a call of a man drowning. Witnesses at the scene identified the area where the victim was last seen struggling in the water, saying that the swimmer began to struggle and then called for help. Divers from the Mason City Fire Department, Iowa Department of Natural Resources, and the Iowa Underwater Search & Rescue Team finally located 49-year-old Mark Gregory Mennen at 8:16 P.M. about 50 feet from the shoreline in about 20 feet of water. Police and firefighters say it’s the first drowning death at Big Blue since November 1993.