What is an apropriate age for a child to swim in a lake?

i'm not a parent but i'd say as long as you stay with him/her while swimming it would be ok.

There is no set age but there are a few factors you should consider:
1. Can your child swim well on their own?
2. Will you be able to supervise them the entire time?
3. Is the lake calm or wavy?

If your child can't swim well on their own, give them floaties and get in WITH them.
Just make sure to never leave them unattended for any amount of time while they are in the lake.