Too many times I've died to the chairs because they didn't render until I hit them. It's one thing to die to them because you saw them too late, but another to die to them because they didn't fucking render until you were on top of them.
I don't think this is possible, as I believe it is a problem with the map being poorly optimized, which is why it is a T act to place the props in there or RDM if appropriate death is caused.
I mean its an optimization entity I'm pretty sure... ima look cause bored It's not... so it must be a convar for prop rendering or something. http://i.imgur.com/EKsGvEI.png
What @tuna♥ said. There is nothing that requires you to jump into the pool. There are at least 2 other ways of getting down
It's the same reason I never used the old pool water pool that broke your fall; it's way too risky to use