THAMES Water is set to be fined more than £20,000 after admitting causing the deaths of 8,000 fish after toxic effluent escaped from one of its plants.

Magistrates heard yesterday that a pipe blockage at a Thames Water site in Pipers Way, Old Town, caused sewage to flow into the River Ray on June 15, 2003.

The flow of sewage was believed to have been caused after a bit of plywood blocked up a pipe.

But the water company's early warning system failed and it took workers more than nine hours to get rid of the block meaning effluent was continually pouring from the facility, which is normally unmanned.

After deliberating, magistrates, who can only fine companies to a maximum of £20,000, decided it was not in their power to give a fine that would be high enough.

The case will now go to Swindon Crown Court, at a date still to be set, where judges have unlimited powers when it comes to fines.

A few days after blockage dead fish were found up and down the river, having been starved of oxygen because of pollution. Some were found dead more than four kilometres away.

The death toll included 80 rare brown trout which cannot be recolonised into the river, which is a tributary of the Thames.

The Environment Agency was only told about the effluent after a member of the public spotted it and rang them, three hours after it was discovered by Thames Water at 3.30pm.

Rod Gould, an enforcement officer for the agency, arrived just before 9pm and claims the water company had still not done anything to clear up the blockage.

Janet Fedrick, prosecuting on behalf of the Environment Agency, said: "This is a very serious matter. In our view, Thames Water failed to inform us properly of the incident and also did not have proper procedures in place to deal with this situation."

The blockage was not dealt with until after midnight, when Thames Water managed to bring in an industrial jet to clear it.

Ben Fitzgerald, defending, said Thames Water deal with 85,000 blockages a year and did everything it could to solve the situation as quickly as possible.

He said it was not the company's fault as it checks the unmanned site monthly and the warning system failed because of a loose wire.

Jamie Hill