And some faces were momentarily a bit red.
However, the Waitaki District Council was not caught on the hop for long, making nimble use of celebrated Muppet character Kermit the Frog to make its point.
"Kermit knows it ain’t easy," the council explained.
"We have had a bit of an incident today."
Council staff had been taking part in a workshop with Enviroschools showing Oamaru Intermediate pupils "the importance of making sure you don’t put pollutants down the drain as it ends up in our natural waterways".
"Unfortunately, our office put a bit too much of the dye in the stormwater line and we have turned things a bit green!"
However the dye used was environmentally friendly and would break down quickly without harming any flora or fauna.
"It does however show how important it is not to put pollutants down drains or on roads as it ends up in our natural watercourses," the council said.
