Use the Empty Cliffspring Falls Sampler to draw a sample of water from the mouth of the cave by the falls. Deliver the Filled Cliffspring Falls Sampler to Alanndarian Nightsong in Auberdine, Darkshore.
The Cliffspring Falls in Darkshore serves as the principle source of drinking water for the region, and now I suspect it is the principle 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.
Once 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.