I'd also recommend environmental interest groups. Seeing some weird chemical get dumped into the water would definitely set them off.

Also something of interest, Brooke brought it up to Edgeworth here about possibly doing a class action suit against Thunder Corp for their actions having such negative effects on people. While it's risky, he's willing to do it and that could also be something involved in this.

And if either of my two can be of any help, they'd be glad to be.