What this section does is clarify that this is now a strict liability offence. You wouldn't have a bystander seeing something happening and then being caught under this. This would be just the actual source of the pollution. It may be coming from a vessel. It could be coming from another source.
The way the court has interpreted this section is that you actually have to prove that they intended to dump. This changes it, so that it would be interpreted as a strict liability. You would still have to have the due diligence defence, but it would not affect folks who are not directly involved in it.