Why water in Windsor’s Grand Marais drain looks neon green

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No, this isn't a very early St. Patrick's Day joke—part of the Grand Marais drainage has been bright green for the past few days.

The neon coloring is caused by a dye introduced into the system to test water system infrastructure, Enwin said.

It is part of the Windsor Public Utilities Commission's Feedermain project. During testing of the system, some of the new infrastructure failed the test, so a dye was added to help identify the source of the problem.

Ducks swim in bright green water in a creek in a border town in southwestern Ontario.
Ducks swim in bright green water in a creek in a border town in southwestern Ontario. (Mike Evans/CBC)

The dye is food-grade and non-toxic and is specifically formulated and certified for use in drinking water, Enwin said.

Once testing is completed, the affected water supply will be flushed and re-tested to ensure full integrity before it goes into service,” an Enwin spokesperson said.

The watershed is in the Grand Marais Road East area, near Langlois Avenue.

Ducks could be seen in the water on Monday.

The water in a creek near Grand Marais Road East near Langlois Avenue in Windsor is bright green on November 17, 2025.
The water in a creek near Grand Marais Road East near Langlois Avenue in Windsor is bright green on November 17, 2025. (Mike Evans/CBC)

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