Sharraxaadda

Our property abuts a next door house. There is a laneway between the side of our house and the back wall of the neighbours house. Our next door neighbour has experienced water problems in his basement and had a contractor come in and put down new concrete. The problem is the grade of this new concrete shifts any water or rain directly at the foundation of our house. He did this because he wants to remedy the basement leakage he is experiencing.

I am sure that this is illegal for him to divert water from his problem area to our foundation. What can we do?