Quick Answer
Return to the Flood Spill Intake on the north side of Water Treatment Control, stand in the water beside the toxic barrel until the objective updates, then travel west to northwest toward the treeline and small river to find the submerged barrel truck. Photograph the truck, search its trunk for the evidence, keep the evidence safe and extract in the same raid.
How to Unlock A Toxic Trail
Complete Source of the Contamination first, then check Shani's quest list. The story continues the same contaminated-water thread even though the trader changes, which is why the quest can be easy to miss if you only look under Celeste.
A Toxic Trail Requirements
You need Dam Battlegrounds access, Source of the Contamination completed, and enough survivability to finish an open-ground route and extract with the evidence.
- Complete the full objective chain in one raid.
- Use a real loadout if you want to reduce the risk of losing the evidence late in the run.
- Keep a safe pocket free for the trunk evidence when possible.
- Expect exposure to patrols and raiders around Water Treatment Control and the swamp.
Where to Return to the Water Intake
Return to the Flood Spill Intake on the north exterior of Water Treatment Control, where the building meets the swamp. It is the same concrete-walled pool used in Source of the Contamination, so you do not need to enter the building.
Approach from the swamp side and look for the toxic barrel sitting in the intake water.
Why There Is No Prompt on the Barrel
The barrel step completes by proximity, so you should not wait for an interaction prompt. Walk around in the water beside the barrel for a moment; if the objective does not update, move closer and keep circling the immediate intake area.
Once the objective ticks, leave the intake and start the truck search. The missing prompt is expected behavior for this step.
Where to Find the Barrel Truck
The barrel truck is west to northwest of the intake, submerged in a small river or flooded channel near the treeline.
- Leave the intake heading west across the swamp.
- Angle northwest as the treeline and narrow water channel come into view.
- Look for the truck sitting partly submerged in the water and approach its side to trigger the photo step.
How to Photograph the Truck and Search the Trunk
Photograph the submerged truck first, then move to its trunk and search it for the evidence. These are separate objective actions, so do not leave after taking the photo.
- Use the photograph prompt while facing the truck.
- Move to the rear of the vehicle and use the trunk-search prompt.
- Place the recovered evidence in a safe pocket if you have one, then head for extraction.
A Toxic Trail Rewards
A Toxic Trail rewards a Tactical Mk.2 plus traversal and area-denial gear.
| Reward | Type | Note |
|---|---|---|
| 1x Tactical Mk.2 | Equipment | A useful mid-tier tactical reward. |
| 3x Zipline | Traversal | Useful on vertical routes and quests that consume ziplines. |
| 3x Gas Mine | Mine | Area denial for chokepoints and pursuits. |
The three Ziplines are especially useful if you are also working on Eyes in the Sky or Keeping an Eye Out.
What Comes After A Toxic Trail
The Stench of Corruption follows A Toxic Trail and moves the investigation to Spaceport. The trunk evidence points Shani toward the sabotage thread that continues inside the Departure Building and its tunnels.
Other Quests at Water Treatment Control
Water Treatment Control also appears in Greasing Her Palms and Paving the Way, while The Clean Dream can overlap the same general session. Stack them when your quest log allows so one Dam Battlegrounds raid covers more than a single objective.
Frequently Asked Questions
Why is there no prompt on the barrel?
Because the first barrel step is a proximity trigger. Stand in the water beside the barrel and move closer until the objective updates.
Why can't I unlock A Toxic Trail?
Complete Source of the Contamination first, then look for A Toxic Trail under Shani rather than Celeste.
Where is the barrel truck?
Head west to northwest from the Flood Spill Intake toward the treeline and small river. The truck is partly submerged in the water.
Do you need to extract for A Toxic Trail?
Yes. After photographing the truck and searching the trunk, keep the evidence safe and extract in the same raid.
Who gives A Toxic Trail?
Shani gives A Toxic Trail after you complete Source of the Contamination.