As you can see the area of the property where I built the house and pond at my place is pretty tight. I was required to put in a curtain (perimeter) drain, shown in yellow, due to a marginal perk test. The septic tank and leach bed, shown in blue, are very close to the pond. The septic system is buried in fill from the pond and the grass grows about twice as fast and much greener where the leach tiles were placed. I haven't seen any ill effects (odor or overfertilization of the pond) from my set up but it is only a couple of years old.
My only other options required some sort of mechanical mechanism/maintenance to operate which I didn't want any part of. There are many lakes where hundreds of homes dump "aerated" sewage into that the fish are perfectly safe to eat. I am no expert but it seems unlikely that a significant amount of anything unwanted would make it into your pond from your proposed layout.
