MYSTERY surrounds the sudden appearance of foam in Milnsbridge.
Joy Black first spotted it in the River Colne at 8.25am this morning.
Mum-of-one Joy, who lives on George Street, said: "Our house backs onto the river. We were just getting ready this morning when my husband said 'Look, the river is full of foam'. We thought it seemed very odd.
"As I walked my son to school, it was spurting out of the drains on Morley Lane too.
"I don't know what it is or where it is coming from, but it seems really strange."
Rob Walsh, of the Environment Agency, said officers were out investigating the sighting of foam in Milnsbridge after concerned residents had reported it.
He added: "We are currently checking this foam out, which appears to be a foot deep in places.
"If anyone knows where it is coming from or has any information that can help with our investigation, we would be grateful if they would call the incident line on 0800 807060."