Never heard of smelly lake water on Winni. The upper end of Moultonborough Bay does have some of the poorer water quality on the lake, see
http://winnipesaukeegateway.org/moni...ing-sites-map/
You can zoom using your scroll wheel like on google maps.
Suggest you give a call to the NH DES water division.
http://des.nh.gov/contactus/subject.htm#W