Yorkshire Water has been ordered to pay a £350,000 fine for polluting a watercourse.
The firm was sentenced after previously pleading guilty to an environmental permitting offence relating to a pollution incident from a sewer overflow near Sherwood Drive, Harrogate in 2013.
At that time, the company reported a blockage in the sewer that caused untreated and unscreened sewage to flow into Rud Beck at Sherwood Drive.
Environment Agency inspectors found the pollution had a significant impact on Rud Beck and the River Crimple, into which the beck runs.
Toilet rolls and rags were found and the water downstream was a cloudy, yellow-grey colour and smelt strongly of sewage. Samples showed high levels of ammonia and low levels of dissolved oxygen, according to the agency.
Yorkshire Water notified the Environment Agency about the blockage but further investigations revealed sewage had been discharging from the overflow before.
A spokesperson for the Environment Agency said: “Sewage overflows of this type can be used for discharging effluent into a watercourse but only in storm situations when water flows are too high for the sewerage system to cope with the increased volume of water. Storm conditions were not present at the time of this incident and untreated sewage entered the beck for 87 hours causing significant pollution affecting over five kilometres of Rud Beck and the Crimple.
“It is not uncommon for foreign objects to enter a sewer and cause blockages and this is why telemetry is so important. The impact of this discharge would have been significantly less if the telemetry had been working properly or if Yorkshire Water had detected the increase in the telemetry levels and responded sooner.”