Wow... it took all the way to the 3rd post before we started looking for someone to blame. We're slipping.
When I was a Boy Scout, the adult leaders were fully in charge and knew how to do it. Maybe it's just that this was 45 years ago, but I do know that there was NO WAY any of us young chirrens were going to be allowed to get close enough to a water hazard that could suck us away.
...Sounds like a leadership problem to me, too....that's also my take on this tragic situation.
As a former scout leader I simply asked the questions anyone would ask. Leaders are responsible for the scouts in their charge.