All it takes is a nosy neighbor to report you (which might even be newcomers to the community), and you'll be surprised how soon they can be a reality.
>First, no one can regulate your collection of rain water.
Again, you'd be surprised.
Or perhaps not, depending on the politics of your Sheriff. In many rural counties where these laws aren't reality it's not because the government doesn't know, it's because it doesn't enforce.
(Of course this same thing happens in cities - just with different laws.)
If there's a lawsuit or formal complaint, they're forced to enforce...
In most of these places you can't be that nosy neighbor too long before increasingly large dead animals show up on your doorstep.
This isn't some nice suburb of SF DC or Boston. Most people frown upon inviting government to show up.