A Dark Threat Looms quest chain

A Dark Threat Looms is a long alliance quest chain which is based in Loch Modan. Most steps either start or return to Chief Engineer Hinderweir VII as the threat by the Dark Iron dwarves is countered.

Component quests
The Chief Engineer wants you to investigate the eastern ramp of the Dam and look for clues. As soon as you go down the end of the ramp, turn left. You'll see two Dark Iron Sappers and discover a Suspicious Barrel at (56,13).
 * A Dark Threat Looms

Return to Chief Engineer Hinderweir VII with your sample of strange smelling powder.
 * A Dark Threat Looms (2)

You are sent with the powder to Ashlan Stonesmirk, the explosives expert in Dun Modr. These means a run through the Wetlands to its northern edge. He is at (50,18), just short of the Thandol Span. This is likely your first visit to the Wetlands, so consider a trip west to Menethil Harbor and its flight path. If you're level 18, you can pick up Daily Delivery on the way and complete when you get to the town.
 * A Dark Threat Looms (3)

Return to Chief Engineer Hinderweir VII with something to disarm the powder.
 * A Dark Threat Looms (4)

The Chief needs you to collect disarming materials. Consider doing Mercenaries at the same time. Loch Crocolisks of level 15 or higher seem to drop the tears. Wood Lurkers will drop the venom, but the Mo'grosh Crystal only seems to drop from the Elite ogres, like the Mo'grosh Enforcer.
 * A Dark Threat Looms (5)

Finally, you can go defuse the threat, a barrel tucked underwater into a corner of the dam (50,14)
 * A Dark Threat Looms (6)

Return to the Chief and receive your prize and the thanks of a grateful nation!
 * A Dark Threat Looms (7)

Rewards
If the player follows the entire quest chain from beginning to end, he or she will receive:

Roughly (from quest turn-ins only):
 * 7,700 XP
 * +350 reputation with Ironforge