I have a small 1/2 acre new pond in an area with quite a bit of watershed. Sometimes we get so much rain that my 12" pipe can't handle it and the water fills up and goes over the emergency spillway.

What is the best and cheapest way to keep the spillway from turning into a grand canyon? I've already got some pretty big gullies from the last heavy downpour.

I was thinking about using my box blade (no FEL) to smooth out the gullies into a rounded channel at the back of the dam and then fill it with stone. Good idea? What size and type stone would stay in place and slow the water down to prevent erosion?

Thanks...