Some of the contaminated water used to clean up the Buncefield fuel depot stored at a Thames Water sewage treatment works has been accidentally released into the River Colne. It is believed that 800,000 litres of the clean-up water escaped from a storage tank at the Blackbirds sewage treatment works, near Radlett, Herts, at the beginning of the week. Shortly after notification the Environment Agency began an extensive sampling programme along the length of the River Colne, and these results are expected to be available from Environment Agency laboratories in Leeds early next week. Three Valleys Water Company does not take water from the River Colne for drinking supplies but has been informed of this incident. The Environment Agency believe the contaminated water was pumped through the sewage treatment works, which may have removed a large amount of the contamination.  Environment Agency staff have not discovered evidence of any impact on the fish or other fauna within the river so far, but will continue to investigate. The cause of the incident is still unknown and will form part of an ongoing investigation. It is the responsibility of the oil companies (Hertfordshire Oil Storage Limited and British Pipelines Agency) to find a safe and environmentally sound solution to the 26 million litres of firewater stored since the explosion on December 11 2005. We await their formal submission of their preferred disposal option.