Pond Overflow - DIY Horizontal Drilling

[Argonne]

Can you post some pictures of the berm and pond?

How about an annotated Google Earth image for now.

- Green line is the berm which at normal pond levels is about 10 feet higher than the water level.
- Blue line is the water path when it overflows at about 474ft AMSL (above mean sea level).
- Red line is proposed passive drain which I hope to be able to core through the berm.

Yes, when the pond is full, the water level is about 6 feet above the floor level of the house. The berm is my friend!
There are no dangers here, only the annoyance of having a stream depositing an alluvial plain right at the pasture entry gate when it overflows. I can, and do, pump the pond down when it threatens to overflow, but I would rather gravity take care of it in a non-destructive manner. Last year I pumped 200,000 gallons, but it was a very wet year. The drain pipe would dump in the pasture on a slope and take it to the ditch on the highway, along with the rest of the runoff from the pasture. As one of you alluded to, I could trench, but would that destroy the integrity of the well established berm? Don't know and won't risk it just to save getting wet once in awhile. Thanks for looking!