A WATER firm whose staff failed to detect a blockage which caused a sewage spill in Nelson has been told to pay almost £10,000.

A prosecution against United Utilities (UU) was brought by the Environment Agency following the spill into Walverden Water last June.

A number of fish were killed in the incident.

The Environment Agency found that UU staff had visited the site in response to an alarm four days before the blockage was eventually cleared, but failed to identify the root of the problem despite there being clear evidence.

As a result, the company has been fined £6,000 with costs of £3,575.

The Environment Agency said it was alerted to the pollution by reports from the public on June 13.

On inspection, Walverden Water was found to be polluted with milky white deposits settling on the river sides and bed.

The pollution could also be seen in Pendle Water where it meets Walverden Water.

An environment officer notified the water company of the pollution.

The investigation found there was a blockage in the sewerage system and this was causing sewage to discharge via a storm overflow.

The overflow should only discharge in times of high flows caused by wet weather.

The blockage was cleared by UU on the evening of June 14 and the discharge stopped.

Ecological surveys by the Environment Agency found that the pollution had a serious impact on the water quality and ecology of the watercourse, with a number of dead stone loach and bullheads discovered.

Simon Boocock, environment officer, said: “The Environment Agency takes all pollution incidents seri-ously.

“The company’s failure to respond to the alarm meant that sewage was discharged into Walverden Water for four days.

"This resulted in a significant amount of pollu-tion that had a serious impact on water quality and the ecology within Walverden Water."

A United Utilities spokesperson said: “The incident occurred due to a blockage in the cCombined sewer overflow.

“We have co-operated fully with the Agency’s investigation and implemented measures intended to avoid a further incident.”