A green river that had St. John's locals scratching their heads on Friday isn't as radioactive as it looks.

In fact, deputy city manager of public works Lynnan Winsor says it's perfectly normal.

The green water flowing in Rennie's River and tributaries like Kelly's Brook was caused by dye tablets used by her department, she said.

According to Winsor, the dye tablets were being used to determine the path of a storm sewer.

She said the dye is environmentally friendly and will disperse.

Earlier on Friday, photos sent to CBC News showed bright green water flowing through the river.

(Cal Tobin/CBC)

On social media, spectators had fun reacting with shock and a little humour.​