The Cliffspring Falls in Darkshore serves as the principal source of drinking water for the region, and now I suspect it is the principal source of the poison that is harming the local fauna - deer specifically.  Use this sampler to draw some water from the mouth of the cave; be careful, as dangerous naga now reside in a cave by the falls.$B$BOnce filled, deliver it to Alanndarian Nightsong in Auberdine.  She is the one that requested our aid, and you will work with her to address this malady.