One of the issues is that the deleterious substance clause of the Fisheries Act is always going to be a bit of a tricky thing to manage. That's because just about anything—the water you're drinking right now—would be considered a deleterious substance if you poured it into the ocean. If I took a bowl of shrimp and put a bunch of water in that bowl, I'd kill the shrimp, because they are marine animals, and I would have changed the salinity of the water.
Concerning the deleterious substance clause, on the one hand we become concerned about deleterious substances because we're worried about truly nasty things, but then sometimes it is extended to things such as effluents from farms, for which you probably could have a standard for releasing that fluid, but until you have that standard, the deleterious substances clause says zero: you can't do it.
That's something that needs to be resolved, for sure.