Neon-green creek traced to non-toxic dye test, ENWIN says

Green water appeared in a creek near Langlois Avenue and Grand Marais Road East in Windsor, Ont., on Sunday, Nov. 16, 2025. (Travis Fortnum/CTV News Windsor)

The mystery behind a creek that turned bright green in south Windsor over the weekend now has an explanation.

ENWIN says the colour came from a food-grade, non-toxic dye used during pressure testing on new watermain infrastructure near Langlois Avenue and Grand Marais Road East.

A spokesperson for the utility said the dye was introduced after a segment of the new watermain did not pass an initial pressure test, prompting crews to investigate further.

In the statement, ENWIN said: “To help identify the source of the issue, the contractor used a food-grade, non-toxic dye in the test water.”

The spokesperson said the dye is a specially formulated product certified by NSF International for use in drinking water systems.

Once the test is complete, the utility said the affected section will be cleared.

“The watermain will be flushed and retested to confirm full integrity before it becomes operational,” ENWIN said.

The bright green water drew attention online Sunday, with residents sharing photos of the almost neon shade — a colour more commonly seen in Chicago’s river on St. Patrick’s Day than in a Windsor creek.

Before the explanation came in, the Essex Region Conservation Authority noted the colour was unusual and stressed the value of residents reporting such discolouration when they see it.

Dr. Katie Stammler, ERCA’s water quality scientist, said the public often acts as “eyes on the ground.”

“You can’t fix something if you don’t know that it’s broken,” she said. “A colour like that isn’t normal … that’s definitely something that I would suggest reporting.”

ENWIN said it appreciates the public’s patience as work continues on the Windsor Utilities Commission’s Central Corridor Feedermain project.