Oh man, I really want Sam to be involved with this but I'm not sure how realistic it'd be with him having a broken leg right now. So maybe he found one of those pieces of evidence? Like...he learned about the reservoir, and other people were able to dig up the additional information?

EDIT: another idea is that, since they'd be pretty far away from the city, Sam could hang out near the back and listen for things with his powers as a sort of watch dog. He'd probably be able to tell, say, when the tanker is closing in on the reservoir, since I'm sure a vehicle's noises would stand out around the various nature/Numbers Club people walking around noises.