Thames Water Utilities Limited (Thames Water) was fined £6000 at Basingstoke Magistrates Court for polluting the Bishopswood Stream in Tadley on or before 6 March 2011.
The company was also ordered to pay the Prosecution costs of £7,293 and a victim surcharge of £15.
The court heard how a blockage on a Thames Water public foul sewer caused sewage to discharge and overflow from an abandoned sewer into an inland freshwater pond and into the Bishopswood Stream. The sewage caused a dramatic deterioration in the downstream water quality and invertebrate community. A carpet of thick smelly sewage fungus spread downstream for 250 metres. During the investigation Environment Agency officers found that a sewage discharge due to a blocked public sewer had occurred in the same location in September 2010, however due to a lower water level in the pond it had not overflowed into the stream. On that occasion Thames Water did not find the blockage and source of the pollution. The company put only temporary bungs in place and failed to investigate potential future problems.
The EU Water Framework Directive currently categorises the Bishopswood Stream as moderate status but the UK is required to improve to good status by 2027. For this reason the Bishopswood Stream is a 'high priority' to improve its ecological quality.
Alison Love, the investigating Environment Agency officer, said:
"Rivers and water courses are an important part of the environment; they offer an essential resource for wildlife, fisheries recreation and commercial activities. Thames Water jeopardised this when they failed to investigate the initial sewage spill properly. This incident caused fairly significant environmental damage which could have been prevented."
"We're pleased with the result of the court today. The Environment Agency will continue to work within local areas and with companies to protect river wildlife. If you see a pollution incident please immediately call our pollution hotline 0800 807060 open 24 hours a day."
Since the incident Thames Water has introduced 19 changes to their business processes improving the way they work and communicate internally and with the Environment Agency. The court's outcome took into account the company have spent nearly £30,000 in remedial costs.