I'll try to post some pics tonight. Not sure where the original leaks came from. I drained the pond a few years ago, and had it dug deeper and smoothed in anticipation for clay. All of the excess dirt was packed on the backside of the dam(dam is very big now). Long story, but the clay never happened. I let it fill back up and dug a few trenches from higher ground to direct rain water. As a result of all this, it now holds water. I still think it fluctuates with ground level water, but I'll take it. Most of last summer it was at the top of the dam level.
Water depth at the dam goes from 18-10 depending if its at flood stage or not. Ideally, it should be at 10-12 ft.
I'll have to research a siphon pipe. I was just going to lay down a pipe horizontally in the trench. I mostly just have to deal with big spring rains and snow melt. Right now its at a good level, but spring rains are around the corner