Residents were left scratching their heads after passing a Leicestershire river to find that it had been turned bright blue.
Parts of the River Sence, which runs from Charnwood Forest and Coalville to Hinckley, were found by locals to have suddenly turned an unnatural shade of blue.
Steph Bickerton, a resident from Coalville, was sent photographs of the neon-coloured waterway by her 11-year-old daughter, Lucie, on Monday, April 24 and initially believed the girl was pulling her leg.
But Mrs Bickerton went out to investigate for herself and found the photos painted the real picture.
She said: "We live just across the other side of Millfield Park. I went with my daughter to look after she sent the first photo on WhatsApp. It really was as blue as the pictures."
The water levels of the river were also very high, according to Ms Pickerton, who also described the water as a "thick cloudy blue".
She then shared the photos to Facebook, to see if other residents had seen it, which lead to many locals trying to guess what had caused it.
Many guessed the water was being treated to kill algae off and one person even questioned if the photos were real, asking if the images had been photoshopped.
But despite the river's vibrant colour, a spokesperson for the Environment Agency told LeicestershireLive that it was harmless.
They said: "The Environment Agency was made aware of the blue water at Coalville in Leicestershire which has now cleared.
"The cause of the colour is drain dye which is harmless to the environment and is regularly used by water companies, drainage contractors and the local authority to detect the flow of water in drains or pipes and to trace leaks.
"No further investigation was required as there was no pollution. Anyone can report environmental concerns to the Environment Agency hotline on 0800 807060."
The river is now reportedly now back to normal levels and its usual colour.
