Working with clay soil

We just moved to the near by area and are dealing with an elevation problem. Our neighbors to the west of us are at a higher elevation. The problem is that they aren't any where around. And they are supposed to be taking care of not letting runoff into our yard, but since they're not around it's allowed dirt to come down into our property and settling on our brand new sod. We are also higher than our est neighbors and it's our responsibility to keep the dirt from sliding into their yard. But we have no idea how to work with clay. What are some tricks and tips that you could share about clay soil that could help with the erosion of both of our yards?