Sewerage discharge pipes are ideally built to take post processed human waste residues far enough out to sea to not be trapped in small bays but to disperse and diffuse through a greater volume of water.
The ideal here might be (I haven't dug into site specific details here) to take any industrial runoff far out to a large volume of water so that it can disperse and not be concentrated in a manner that creates a time bomb for human food / water inputs.
If that is the intent, then unsealed ditches crossing watersheds is a bad idea compared to sealed pipes with deep water discharge.
The ideal here might be (I haven't dug into site specific details here) to take any industrial runoff far out to a large volume of water so that it can disperse and not be concentrated in a manner that creates a time bomb for human food / water inputs.
If that is the intent, then unsealed ditches crossing watersheds is a bad idea compared to sealed pipes with deep water discharge.