Thames Water has been fined after polluting a river with sewage sludge that killed hundreds of fish.

The water company was ordered to pay £27,779.15 for contaminating the Engine River, near Walton Lane, Weybridge, in November 2011.

Staines Magistrates’ Court heard raw sewage burst from a Thames Water pipe and flooded a field behind Walton Lane sewage pumping station, which then entered the river.

Environment Agency officers estimated a minimum of 1,550 fish, including perch, roach and carp, were killed by the spill, which Thames Water failed to contain, between November 4 and 15.

The court heard Thames Water said it had shut off the flow after the pipe burst and that the spill was only affecting the top part of the river.

But an Environment Agency officer visited the site and discovered a “volcano” of raw sewage erupting from a hole in the field, so advised the water company to contain it with sandbags.

The court heard Thames Water did not make sufficient efforts to contain the pollution and sewage water seeped further downstream, affecting more than 1.2km of the river.

A member of the public also reported pollution in fields where horses were kept.

Thames Water said it did not contain the pollution immediately after the pipe burst because it did not want to take heavy machinery on to the field.

Thames Water Utilities Limited, of Clearwater Court in Reading, pleaded guilty to the charge and was fined £18,000, ordered to pay costs of £9,764.15 and a victim surcharge of £15 on Friday, May 24.

Environment Agency solicitor Marie De Viell said: “Rivers and water courses are an important part of the environment; they offer an essential resource for wildlife, fisheries and recreation.

“It is distressing when incidents such as this one occur and cause fairly significant environmental damage, with several hundred fish killed by this sewage spill.

“The prosecution and fining of Thames Water sends a clear message to other companies that if you fail in your environmental responsibilities you may be prosecuted.”