Flooding my neighbors out - Yard leveling question.

[Kirk R.]

I have a back yard that slopes back into the screened porch which is on a concrete slab.

I live on a fairly good slope toward a river.  I want to turn the porch into a sunroom.  But if water might get in there... 

I talked to some Bobcat guys and they said that I would be liable for the damage to my neighbors if I start changing the flow in my back yard.  I do not want water dumping into my neighbors - but I am higher than my neighbors.

Would I be liable?  

What the bobcat guys said would probably be best is to put some concrete forms around the sunroom so I could get the dirt up against the bottom of the sunroom to create the slope.  Any ideas.