As far as this very specific case is concerned, the offence was not due to the fact that the company was dumping substances. These ponds are indeed designed to store processing residue. Under their permit, however, these people should have made use of tools, of very specific measures, to ensure that birds would not land on these ponds, for example, nets, warning signals and so on.
On March 26th, 2009. See this statement in context.