I install septic systems regularly here in Mo and deal with them everyday, and there are a ton of problems with onsite systems and ponds.
Number one, your system should Never discharge into the water, aerator or not, they nixed that theory a long time ago here, and pretty sure figured that out everywhere, IL is pretty strict with regulations, probably even more so then in MO.
When you have a lateral daylighting into the pond there is no incentive at all for it to absorb into the ground and be treated by the dirt, it will always follow the path of least resistance straight into your pond. jmo
