I have determined where the corruption is coming from.  It is the by-product of some demented research and you're going to put an end to it!$B$BJust to the southwest of the Foul Pool is a small camp.  There you will find the 'research' of Tel'athion the Impure.  This is where he produces the filth that has been seeping into the island's water.$B$BUse the pure water you obtained from Ashenvale to destroy his cache of barrels.  That will be sure to bring him out.$B$BWe will have an end to this!