Okay, photos. I'll give it a try.
First photo - The culvert is just to the left of the photo, running under the dam. It catches pond overflow.
Second photo - Culvert is directly below where I'm standing to take picture (on top of dam).
I will take a close-up of inside the culvert this weekend.
One of my first posts in mid-September ("It doesn't get any better than this") had these pictures, plus a couple more.