EAST PALESTINE, Ohio (WJW) — Environmental advocate Erin Brockovich and water expert Bob Bowcock spoke Thursday on their investigative work into the village’s wells and well water following the Feb. 3 derailment of a Norfolk Southern train, spilling toxic chemicals.

It’s Brockovich’s second visit to East Palestine in a week. At a town hall-style event at the high school on Feb. 24, she said though testing may currently show the village’s water supply has not been contaminated by the spill, “tomorrow, that might not be the circumstance.”

Bowcock, a former water utility manager in California, said the contaminants are expected to migrate over time, and it may be six to 12 months before they pose a threat to the water supply.

To that end, cleanup workers have installed sentinel wells to monitor the flow of contaminants in respect to the village’s well field.