What's with the private lake in Rockcliffe Park?

There's a pond in Rockcliffe Park that's a bucolic swimming hole. But the lake right next to it is off limits to the public, and only residents who have homes backing on to it can swim in it. How did this come to be?

What's with the private lake in Rockcliffe Park?
view of west side of McKay Lake from east side conservation area

There's a pond in Rockcliffe Park that's a bucolic swimming hole. But the lake right next to it is off limits to the public, and only residents who have homes backing on to it can swim in it. How did this come to be?