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 in March 2011.

The sewage caused a dramatic deterioration in the downstream water quality and invertebrate community.

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.

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 a ‘moderate’ status but the UK is required to improve it’s waters to a ‘good’ status by 2027.

For this reason the Bishopswood Stream is a ‘high priority’ to improve its ecological quality.

Investigating Environment Agency officer, Alison Love, 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”, she added.

Thames Water was also ordered to pay the prosecution costs of £7,293 and a victim surcharge of £15.

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 that the company has spent nearly £30,000 in remedial costs.

Leigh Stringer

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