A carp bit my friend on the belly button when she was swimming in LO. I kid you not. Sorry, I'm not much of a help. Besides, the hungry carp incident was in the 1980's (I'm sure a carp can't take you down anyway).
There is of course the city swim park. I am a good open water swimmer, but the number of speed boats has scared me off. Anyone know of a place closer than Hagg?