I am building a road around the front of my lake. We have a creek coming through the pond. I just removed the old concrete pipe we had for 50 years. I am putting in two sections of the double wall poly pipe that is 18in. in diameter. Since I have raised the water level above the original level, I was wondering what the approximate height the pipe should be above the water level? Or does it really matter as long as you dont want it backing up into the pipe?

Travis will there be a continuous flow of water thru the pond? Also, do you have a spillway in case the waters get to high for your pipes to handle?

Travis, is the pipe for dam overflow or somewhere for inflow?

Not a continuos flow. And yes.

Travis, if those "yeses" are for me then you sound like you're in good shape. What I did in a very similar situation was have on 24" pipe that allowed about 1" of continuous flow
(which still allowed for a lot of extra water) and added another 18" pipe (set about 18" higher than the main pipe) and then the spillway - the spillway did get used a couple of times in spite of what I thought was "overkill" with the two pipes. The 2 pipes were about 50' apart on the dam.