A river has been turned orange after iron deposits were washed into it from a disused mine.
The Environment Agency (EA) said officers were investigating what had discoloured the River Calder, at Todmorden, on Thursday.
However, the EA said on X it was believed iron deposits had been carried into the river by water from an abandoned mine.
It said it did not expect any “significant or long-term water quality issues” following the incident.
A number of pictures and videos of the orange river have been published on social media.
The Calder Rivers Trust said it was aware of the incident which had been reported to the Environment Agency.
It is not the first time the Calder has changed colour with similar incidents reported in 2022 and 2014.
The river is expected to regain its normal appearance within a few days.
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