Your water inlet in the last two pictures is clearly going to be an erosion problem. I assume you are intending to use that runoff from the 20 acres of woods to keep your pond full?
Does that water run fairly clean from the woods after a heavy rain? How big is the culvert/road tile where that water passes under the road?
If that water is clean, then you might add some inexpensive corrugated drain tile (flexible pipe) for the last stretch of moving the water from the exit of the road culvert into the pond. Your pipe should enter the pond below your expected normal pool level.
Landscape with a ditch parallel to the road and then run the drain tile 90 degrees into the pond, or do an angled ditch from the culvert towards the pond and then go underground with the pipe for the last portion. (Do whichever path matches your surface landscaping plans better.)
If you size your drain tile pipes to exceed your culvert size, then you shouldn't suffer any more erosion at that location. (Just remember, that the math shows it takes four 6" drain pipes to equal a 12" culvert.)
