South West Water is to pay £89,000 in fines and costs after a sewer overflow which should only discharge during storms polluted a stream with sewage for up to two days.
Exeter Crown Court heard that around 150 fish were killed as a result of the sewage discharge from Ham Lane combined sewer overflow (CSO) into a stream in Woodbury, near Exeter, leading to the prosecution by the Environment Agency.
CSOs are allowed to discharge during storm conditions to prevent the internal flooding of properties, but they are not permitted to operate during periods of dry weather, when sewage will not be as diluted by stormwater.
The spill, in September 2014, was caused by a blockage that resulted in effluent being discharged into a nearby stream over one to two days.
The water company must report any fish kills that occur following a pollution incident. However, it failed to report this information to the Environment Agency.
Instead, a witness alerted the Environment Agency to the seriousness of the incident after seeing South West Water staff collect and remove dead fish from below the CSO discharge pipe over several days as part of its remediation work on the stream.
The dead fish included minnows, stone loach, bullhead and eels.
Pete Ball of the Environment Agency said: “It is important water companies regularly inspect and maintain their structures and assets such as CSOs to ensure they are operating in accordance with their permit and do not cause pollution.
“While South West Water responded quickly to this incident, it failed to report the extent of the environmental impact of this spill, especially the fish deaths.”
South West Water was fined £70,000 and ordered to pay £19,023 costs after pleading guilty to breaching its environmental permit for Ham Lane combined sewer overflow.