The Environment Agency (EA) said it found pollution in the stream in September 2013 and again in December 2013, which affected a 400 metre stretch of water and impacted on river life.
The court heard equipment failure and poor management on the part of SWW led to poorly treated sewage entering the Craddock stream near its Ashill Sewage Treatment Works.
The company said it “regrets and accepts” that Ashill Sewage Treatment Works “was not operating as effectively as designed on two occasions in 2013”, but added that it believes there was “no adverse impact” on the Ashill stream as a result.
“On each occasion, as soon as we became aware of the issues an operator was sent to site and took immediate remedial action,” a spokesperson said. “We have since taken steps to improve the performance of the works and have submitted proposals for a long-term solution to address population growth in the village to the Environment Agency.”
However, the judge decided SWW had failed to keep an effective watch on the maintenance and operation of this site since September 2013 and “should have made more effort” to ensure the site ran properly and that its maintenance programme at the site was sufficient.
The EA told the court spotted sewage fungus in the Craddock stream on 11 September 2013 and found excessive sludge in the treatment process, and blocked filters which would usually efficiently treat the sewage.
A biological survey of the stream showed that the sewage had been poorly treated for at least a month, and further investigation revealed SWW knew of the poor stream condition. Ongoing problems were observed during a later visit on 12 December 2013, when the quality of the sewage remained poor, the EA said.
Spokesperson for the agency, Mischka Hewins, said: “We carried out regular checks on the watercourse in 2013 and saw pollution on two occasions. An ecological survey revealed that there was a detrimental impact on the invertebrate fauna of the stream as a result of the sewage treatment discharge and significant changes to the wider ecology of the stream.”
The verdict comes weeks after SWW was fined £214,000 fine for allowing a large amount of sewage pouring into the River Tamar from its Camels Head works.