A river in Buxton left residents bemused when its colour mysteriously turned bright green.
This photograph, taken yesterday (Friday) by Twitter user John Yates, shows a section of the River Wye adopting the striking new look, sparking fears that pollution was the cause.
However the Environment Agency reassured residents that the change was only temporary and the result of specialist dye testing by officers.
An EA spokesperson said: “On Friday April 10, Environment Agency officers used dye in the River Wye to investigate the relationship between underground waterbodies and the river.
“The dye is a distinctive green colour but will not harm the river or any of the wildlife.
“We notified the local fishing clubs and they are aware of the investigation. It is expected that the green colour will pass through today.”