YORKSHIRE Water has been stung with a five-figure fine for polluting the River Holme.
The company pumped waste from a sewage works in Brockholes which was 40% dirtier than the law allows, a court was told.
Yorkshire Water pleaded guilty at Huddersfield Magistrates' Court yesterday to two charges relating to its treatment plant at Neiley, near Brockholes.
Handing down a fine of £10,000 plus costs, magistrate Gillian Tankard made clear the incidents were significant.
She said: "These are two very serious environment offences.
"Clean water is a reasonable expectation - both for consumption and for wildlife.
"While these breaches were not deliberate or motivated by cost, any such breach always presents the risk of doing considerable damage."
Earlier the court heard how the Neiley plant had failed Environment Agency tests five times in 2005 - two more than is allowed in a year.
The plant is allowed to pump treated sewage with a biochemical oxygen demand (BOD) of 21 milligrams per litre into the River Holme.
But, after failing three tests earlier in the year, water at Neiley was found to have a BOD of 29.4 mg per litre on November 2, 2005 - 40% over the legal limit.
Three weeks later water with a BOD of 27.5mg - 30% more than allowed - was found at the plant.
Yorkshire Water's solicitor told the court the failures, which he put down to problems with the plant's filter system, had not caused any fish kill or long-term damage to the Holme.
Quality tests had to be made some four miles downstream from the sewage plant.
The company was fined £6,000 for the first breach and £4,000 for the second and ordered to pay the Environment Agency's costs of £753.
After the court case, Environment Agency environment officer Andy Mollitt said: "Rivers in West Yorkshire are recovering from their industrial legacy and it is vital that businesses take responsibility for their actions and ensure that the environment is protected."