Anonymous wrote:Put a plastic barrier on you property to divert it back. Just that plastic landscaping to keep mulch in.
Basically this +1
You need to take action to protect your property from the water run off.
Most courts, I think DC for example treat rainwater run off as a "common enemy".
Did your neighbor alter his property/land in anyway that makes the rainwater run into yours, other than the gutters?
If so this might be considered "unreasonable" and you could make your case in court for damages to your property.