My syphon system is two 6 inch pipes sharing a single vent. The entire system is inside of the dam. I used a 10 inch sock pipe to bring the water level of the pond inside the dam to the vent. Not pictured is the 18 inch piece of culvert pipe I put over this that acts as a pit. I ran a 4 inch piece of pipe to the surface with a grate flush with the ground for the air to enter. I also capped the pit with a concrete cap and covered it with dirt and grass. My dam is 3 feet higher than the water level and I live in an area with an 18 inch frost depth. Even in southern climates, You wouldn't have to worry about debris clogging the vent or having a pipe to mow around with this design.
Edit: I'm adding a drawing that isn't exactly to scale of what I did, but maybe is representative of my design.
I extended the sock over the tee to keep any dirt from entering the sock pipe as I backfilled. I removed it once I had everything backfilled and compacted.
This is the inside face of the dam.
The sock pipe is covered in #2 gravel.
Here is the syphon in action.