Yorkshire Water has been fined for polluting a beck in West Yorkshire.
The company, based in Bradford, was fined £5,000 and ordered to pay almost £2,600 in costs after pleading guilty to polluting a stretch of Pudsey beck.
Leeds Magistrates' Court was told raw sewage was pumped into the beck at Troydale from a sewer overflow at the company's Smalewell site.
The company blamed a piece of wood which had blocked the sewer pipe and said the alarms had failed to activate.
The charge against Yorkshire Water was brought by the Environment Agency.
Dead aquatic life
In a statement the agency said the event was classified as category one - the highest level.
The agency said its officers had been alerted to the pollution by a member of the public.
Yorkshire Water was contacted and they discovered the pumps at the overflow were not operating which meant raw sewage was being discharged into the watercourse.
On a second visit, the Environment Agency found the discharge had stopped but the beck was still heavily polluted. A biological survey showed up to 58% of small aquatic animals were dead.
In mitigation it was said that Yorkshire Water had been co-operative with the agency through its investigations and had never had a previous problem at the location.