Hi, I was wondering how much of a channel my overflow should cut before I added riprap. Not knowing exactly the course overflow water would take, I did not hurry to get the rock in. I now know the direction it wants to go, but how deep should it be before adding rock? I was also wondering if I should add riprap along the front of the overflow as well. By the way, the entire dam and all edges of the pond have a very good start of fescue growing around them that should be pretty well developed by summer's end.

Thanks

I assume you are talking about how deep you should let the water erode the ground?

I would think that if that's the case, you better get it fixed as soon as possible. I would install a permanent overflow PIPE instead of letting the water constantly erode the dirt.

Sorry for the confusion. Let me try again. My pond dam is 100 feet thick at its greatest. I've got an 18 inch overflow pipe in the southeast corner of the dam that regulates the pond's depth. The pipe is, of course, buried and 70 feet long. Since the pond just filled, I didn't know the exact path the overflow water would take on the backside and I held off riprapping it. With all the recent rains, I can now see where the water will go and was wondering how long I should let it go before adding some riprap or if I need it at all with a good stand of fescue. I mean, most good field waterways are all fescue and no rock.

Do NOT wait for it to find it's own path!!! Trench and rip rap the path to ensure it goes AWAY from the excavated dam and beyond with no questions.

Waiting may cause the flow to enter the toe of the dam and wash it away in a catastrophic way on a single rain event within minutes!

Field waterways don't have a high velocity, concentrated flow. Whether to rip rap the inlet of the overflow pipe depends on how far it extends into the water and if the whirlpool created when draining is sucking away the dam from the inside.