Last major storm or see it as a one-off event

What the flood wardens have said for years is that what we need is a good flood, to make people aware of the danger, but of course, by the time you have a good flood, it's too late.  

The memory of the inconvenience, the tragedy, all that, just dissipates as time goes on, and because it wasn't in living memory, people think it won't happen again, it was a one-off event and it's out of their mind.