Data from a china clay mining company is to be reviewed by the Environment Agency after a stream near Truro turned milky white.
The stream in Coombe is a contributory to the River Fal and after heavy rainfall on Friday turned from brown to white and opaque overnight.
A spokesperson for the Environment Agency (EA) said they thought the discolouration was “linked to water from the Imerys china clay operations”.
They said the mining company had a permit for emergency releases of water within 48 hours of heavy rain to protect its infrastructure and the EA would investigate the discharge monitoring data to check compliance with the conditions of that permit.
They said: “We permit their releases of water from their operations, and these discharges are closely monitored for suspended solids – such as the china clay visible at Coombe.”
“We will be investigating the discharge monitoring data associated with this rainfall event next week with Imerys to check compliance with their permit conditions,” the spokesperson added.
Imerys extracts and processes about one million tonnes of china clay (kaolin) each year at more than 20 sites across Cornwall for use in a variety of products including ceramics, paints, cosmetics and pharmaceuticals.
The sites include a research and development centre at Par Moor and the Melbur kaolin open pit mine which lies between Ladock, St Enoder and St Stephen-in-Brannel.
Imerys has been contacted for comment.
