Drain Schematics

As a prerequisite to this item dropping, you must have completed As the Crow Flies, given by Ysiel Windsinger in the Cenarion Refuge in Zangarmarsh.

This quest given by this item ultimately leads to one of the quests available for the Coilfang Reservoir Instance Hub.

Source
This item drops from Bloodscale naga and the Steam Pump Overseers in Zangarmarsh.

As a quest objective
This item starts Drain Schematics (quest).