When it comes to agriculture, the tradition has been to try to educate, to incent, to work with landowners. The reluctance to regulate or to really quantify this polluter pay idea is that you would have to know precisely who is contributing what. The nature of phosphorus from agriculture is that it's insidious; it's a small amount from the entire landscape. It is extremely difficult to establish, for purposes of determining who is financially responsible, who has actually contributed that phosphorus.
Now, we do have techniques for tagging the phosphorus and following its migration through the system, but that approach has generally not been favoured. There's certainly a legitimate argument that excess phosphorus moving out of the farm system should be the responsibility of the producer. That is an approach that would be up to governments to determine.
There would obviously be significant pushback from the farm community. It seems, then, that if that's an added cost to production, which many industries have been forced.... The trick is that in agriculture, as price takers they're competing in an international market in which other jurisdictions are in effect financially supporting theirs.