Dude if there is, it's a load of hogwash, for a few reasons. 1) I know people who have been diving there for 20yrs and never been stopped 2)on any given day there are twenty divers in the water in plain view of the inspectors who watch from the mountainside. Inspectors have checked my licences and sizes but nobody has ever told me that I can't dive there. 3) Soetwater is run by the city council and I personally know the man in charge of the whole area, I met him on Monday, In fact we even took out a few kreef for him as well. 4) I've never seen this sign in the three years I've been diving there.
So it's very unlikely to impossible.
So it's very unlikely to impossible.