That's a good article on the subject of water viability, I really believe Daniel could figured parts of some report out and tried telling his company about it. That would also explain why Roger said he saw Daniel at the office twice in the days leading up to him going missing, Daniel could have been bringing what he found to his company, Roger also said he was carrying a box, it connects very well.
According to Tempe PD they have a reason to believe its a criminal case, I'm inclined to trust the Tempe Pd. Now you didn't get this from me, and I'm going to delete it in a bit, but the Mayor of Tempe is really nice guy and he might have told a little birdie that Tempe PD is actively investigating right now.