Excavation and diversion of public water resource

There is a public canal on the west side of my land's boundary which feeds to a pond in my neighbours land. This pond is there from atleast 70 years. Now my neighbour has filled the pond with soiland rock and diverted the flow of water from where pond was there to a different area of his land. My land is at a higher altitude (atleast by 6 to 7 fet) than my neighbours land. Adding to this he digged almost 2 feet deep right on the corner of my boundary. This is currently exposing the basement of my wall we can actually see the basement stone. With monsoon arrived, water is gushing through the canal causing the soil around my wall erode and my wall and my house is at a risk of damage. Since our land is at a higher altitude we worry the entire house may collapse too. Post filling the pond with soil and rock he diverted the flow of the water to a different area in his land. Now with heavy rain there water clogged around the wall and making it even dangerous. We tried co.plaining in the municipality however they are not even ready to take good look at it. I am terrified as my old parents are living alone in that house and am afraid if anything worse would happen to them. He has not left 1.5 feet distance from our boundary for digging. Can someone please help me understand what can be done here.