Pond Boss Forums POND CONSTRUCTION Building a dam Dam with two pipe spillways

pond girl:

Here is how my second pond's drain pipe outlet is setup. There is a bowl which holds water when the drain is running. This way the energy of the falling water is partially expended when it hits the water in the bowl. You can see the bowl is lined with rock big enough to reamin in place with water flowing.

This particular output is an 8" pipe with rocks about the size of a football. Since the pond filled in February, it has been successfully resisting any erosion or movement that has incuded a full 8" of water entering the pipe.

For a much larger pipe, like yours, larger rocks (MUCH larger, as you have noticed), a concrete basin, or very well anchored timbers would be needed to resist the flow of the water. But I think having a water basin to discharge into would also be useful in your situation, regardless of what you line or form it with.