What a horrible tragic accident. Like many others my first thoughts are with the family, as well as the people who witnessed and tried to help. Unfortunatley you can not prevent all accidents. As much as we want to "bubble wrap our kids" it just can't be done. With that said you can not make rules to protect from all situations. Sometimes things just happen, no matter what rules, policies are in place, thats why they are called accidents. To think that policies or rules or BIGGER signs or more rules will make things safer is just not the answer. Sometimes there just are no answers. While it pales in comparison to the the tragedy I think it is unfortunate that the OP suggests that the issue may have been lifeguards (who were not on duty). Even if they were, the best lifeguards can not prevent all tragedies.