River Cam runs bright blue and baffles onlookers as environment inspectors mount probe
![River Cam runs bright blue and baffles onlookers as environment inspectors mount probe](https://i2-prod.mirror.co.uk/incoming/article32738786.ece/ALTERNATES/s615/0_River-Cambs.jpg)
Images posted to social media saw patches of blue running along the edge of the river in Cambridge, leaving baffled residents questioning what had happened
Images posted to social media saw patches of blue running along the edge of the river in Cambridge, leaving baffled residents questioning what had happened