A cheesemaker has been fined about £23,700 after polluting a watercourse with a liquid that smelled like milk.
Alvis Brothers Ltd, which makes Lye Cross Farm cheeses on a site near Bristol, admitted to causing discharge of poisonous, noxious or polluting matter, for a third time.
The firm's operations director Nick Green apologised to the court.
The Bristol Magistrates judge said the company failed to report it as "they hoped to get away with it".
She ordered Mr Green to tell the court under oath how many times they had self-reported a pollution incident, to which he replied "zero".
He also talked through the measures taken after the firm became aware of the spill.
Alvis Brothers Ltd was fined £20,000, ordered to pay costs totalling £3,520.20 and a victim surcharge of £190.
In September 2020, following reports of pollution, Environment Agency officers went to a tributary of the Congresbury Yeo, near the farm and found the water was milky both in colour and odour, the court heard.
It was found to have been caused by a blockage of a plastic bag containing gloves and other plastic in a pipe that took wash water from Alvis Brothers Ltd's production facility to onsite treatment works.
The Environment Agency maintained the materials that caused the blockage were "clearly inappropriately disposed of, there appeared to be no form of alarm to notify of the blockage to the drainage system or of a spill and while the pollution was clearly visible it was not reported".
The judge said because of the company's history of offending, she was not surprised that their offer to the Environment Agency (EA) of paying an Environmental Undertaking sum was rejected.
Jo Masters, senior environment officer for the EA, said: "This is the third time Alvis Brothers Limited has been prosecuted since 2015 for polluting the watercourse.
"We will take action where offending is repeated and offenders aren't willing to change their practices."
Alvis Brothers Ltd supplies a number supermarket chains, including Waitrose and Asda, and exports to more than 40 countries.