A lake can be unsafe for people to swim in yet have a healthy ecosystem and vice versa. Or, if your reading is correct, redundancy might be an aesthetic choice.
Interpreting "healthy" as "healthy ecosystem" doesn't really make sense in the context of an initiative focused on people being able to swim.
This thread gives me the vibes of arguing for the sake of arguing. The first point mentions "safe" and "healthy", of course this initiative cares about both good water quality and safety from drowning, because those are quite important things for people wanting to swim.
You must be new around here
The commenter you respond to joined HN 4 years before you, with 10 times more karma points.
I know; it was a tentative to make the thread more serious than these snarky, unconstructive comments.