Pond Boss Forums POND CONSTRUCTION Building a dam Spillway construction

Help! Trying to have my pond spillway rebuilt and not sure what elevation to use. Pond is about 6 years old, less than 1/2 acre x 10' deep, surrounded by heavily wooded, some farm fields. The spillway has been washed out from heavy Spring and/or Fall rains. Located in MD. I think the drain pipe level was too high initially and that caused the spillway to wash out and now the spillway is about 1 ft lower than the drain pipe-making the drain pipe useless and my spillway continues to erode. The pond is stream fed, which dries up in the summer. Water level is about 3-4 feet down now, due to drought, and I'm having a concrete spillway put in. He's recommending to set the spillway level 1-2 inches above pipe level. If I think I'm reading some of these forums correctly, it looks like that spillway should be 12" higher than the pipe? It will be about 12' wide. Any recommendations?!

Hopefully one of the dirt experts will answer quickly. I seem to remember that 12" figure to be about right, (primary to emergency overflow/spillway) and the emergency spillway should be 1' to 3' below the top of the dam.

But, since I don't have to deal with dams, I could be all washed up (and out). The majority of ponds around here are dug ponds.

A better way to look at setting the emergency spillway elevation is based on the height of your dam. You want the emergency spillway low enough that the water will not rise so high as to escape your emergency spillway. The higher the emergency spillway, the less it will be used and the less damage it will see. The pipe will also carry more water the higher the water gets over the top of the pipe. So higher is better unless you risk the water backing up and running over your dam or otherwise temporarily flooding areas you do not want flooded. I have a very high and wide dam and wish my spillway was a foot higher so it would get used less (now used a little less than once a year but has held up OK).

my recollection is
emergency begins to run at 12" over top of primary pipe
Top of dam no less than 2 feet above water level in a fully charged emergency spillway
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additional notes
add a hooded inlet to the primary pipe

A lot depends on the size of the watershed and the rainfall that one gets. I have BOW at both extremes of watershed size, and size does matter...