Underaged children into swiming pool

Bally Fitness Center in Sheepsheadbay Area, Brooklyn NY, allows unattended children under age 18 to swim by themselves into swiming pool. Besides the point that this is dangerous, it causes a lot of inconvience for Balley members. Children are loud, they dive, scream, jump, change lines etc. They have no chaperon. When I complaint to the management, I was told that the Life Guard supposed to be responsible for their behavior. I don't think that this is Life Guard job. Also I would like to know since when it's allows in NYC for relatively underaged children ( some of them looked even younger that 10-11 years ) to be left alone in the sport facility, go home by themself  after 7:00- 8:00pm.
Please respond on my complaint on my e-mail adress: alextarasula@yahoo.com