Residents were left puzzled after a town centre lake appeared to turn a peculiar shade of purple.
After reports of “really dark” water, samples were taken from the popular facility, at Eirias Park, Colwyn Bay, which were compared to “weak Ribena”.
It left some residents wondering if the lake’s condition was responsible for an apparent death of pond life such as insects and tadpoles.
However, after a dad shared images of the lake, showing its purple water, on social media, it became clear a dye had been added to the former boating lake.
It was added at the behest of Colwyn Bay Model Boat Club, whose members have worked diligently to improve the lake’s appearance and condition over the past six years.
The club said blue dye was added on the advice of ecologists to increase the water’s opacity and so prevent sunlight reaching the bottom of the shallow lake.
In a Facebook post, a club member explained the lake would quickly return to its former condition without active intervention. “The club, working alone, has spent six years keeping the lake alive by managing the weeds,” he wrote.
“If the boating lake is left to its own devices then it will become overgrown with weed and algae. Soon it will support no life at all.”
Prior to 2016, the lake was periodically cleaned out by Conwy Council but since then the model boat club has taken on the role.
Members meet almost weekly to maintain the site to ensure it is suitable for sailing model boats.
They were advised that the dye would be the best way to manage weeds and control algae.
However, some Eirias Park regulars wonder if a little too much dye has been added.
One dad has noticed a “definite decrease in sticklebacks and other small pond life”. He added: “This loss of life and the colour of the water cannot be a coincidence.”
Others noted the lake was “devoid of insects completely”.
One family’s recent trip returned no fish or tadpoles, just “some leeches and water boatmen”.
The Model Boat Club said it was aware of the problem and was working on solutions with “nationally famed lake management experts”.
One issue might be the current dry spell, which may have concentrated dye levels as well as depleting oxygen levels in the lake.
A club member said: “At the moment we are simply trying to stop the lake from becoming a stagnant pit of algae. Just two years of no action will see the lake destroyed by weeds and algae - then nothing survives, nevermind thrives.
“The lake was designed as a shallow boating lake that for 60 years was deliberately devoid of wildlife. Now we are trying to adapt it. We are already in discussion with ecologists, Friends of Eirias Park and the council about creating more support for wildlife.”