The Cliffspring River has begun turning foul and corrupted. It empties into the Mist's Edge, and I fear the wash will affect Auberdine soon. I suspect the Blackwood furbolgs up-river are the cause of the taint, but I also suspect that they aren't the true root of it.
Take this sampling tube and go to the mouth of the river to our north. Proceed inland to the first waterfall and draw a sample from the pool there. You'll see a bridge overhead. Once you have a sample, return to me in Auberdine.
It's no surprise how tainted this water is, but just look at how putrid it is becoming! It would seem that action is needed sooner than later, eh <name>?
To our east is Felwood; it is the real source of this corruption, one that I have seen in times past. I predict this sample will confirm this. We might be able to enact a cure for it here, but in order to even try we will need assistance. When that time comes <name>, I hope you will be able to give the aid we need.