Hi Wolfgang. I spent many days in Patchogue when I was a kid. My grandparents lived there and also a bunch of uncles and aunts. My uncle owned a small resort hotel and restaurant near the shore that went belly up in the 1960s. Back in the 30s and 40s, Patchogue was known as a resort town and was quite a popular vacation spot.
I remember the lake, if it's the same one I'm thinking of, Ibelieve it was in East Patchogue. There are also a number of inlets around where there used to be a lot of private boats, and I believe a couple more lakes..