My lot is higher and has always drained to that lot. Tens to hundreds of thousands of gallons of water run through this lot, diffuses out across it, and drained through a drain on the front. It has been this way for the history of the subdivision. When notified about the build, I shared photos and video of the water that flowed through the lot with the homeowner, the excavator, and the township. I reminded them and again expressed my concerns when they brought 100+ trucks of fill. So far this spring, their yard has caused an ENORMOUS backup of water on my lot and up to my foundation as much as 18" deep. Are they responsible? What can be done? We are looking to move back to Milwaukee...Can I ever sell my house?