7/5/11- Authorities continue to investigate at least four drowning incidents in Wisconsin during the July Fourth weekend. In Waupaca County, a man drowned Sunday while trying to retrieve a boat in the Manawa Mill Pond. Authorities said the boat got untied from a rope he was holding. And he was swimming to catch up with the craft when he got caught in a current and was pushed underwater. In Green Lake County, officials said a 25-year-old man was boating on Lake Puckaway when he jumped in for a swim – and he could not return to the boat after it drifted away. The other two incidents were in Polk County in northwest Wisconsin. A 22-year-old Saint Paul man drowned Sunday when a boat in which he was riding capsized on Antler Lake. And Polk County officials said 53-year-old Ronald Carlson of Centuria died Friday after he dived head-first into shallow water off a dock on North Twin Lake. Names of the other three victims were not immediately released.