Food giant Dairy Crest has been fined more than £1.5 million for repeatedly discharging illegal levels of sewage into Cornish river systems from the UK’s biggest creamery.

The Davidstow Creamery in north Cornwall operates 24 hours a day, seven days a week, processing 1.3 million litres of milk from 370 dairy farms every day.

Between 2016 and 2021, the site regularly breached the conditions of its permits that allowed it to pump wastewater into the River Inny, a tributary of the Tamar.

During the time it was operated by Dairy Crest, now known as Saputo Dairy UK, which had profits of £21 million last year.

The site had its own wastewater treatment facility, but it struggled to cope with increased volumes of effluent when it expanded its operations in 2014 to include a plant for “probiotic” dairy products.

It breached legal limits of discharge of phosphorus, ammonium nitrate, suspended solids and oxygen levels, and also subjected nearby residents to overpowering odours that kept them inside their homes.

In December, Dairy Crest admitted 21 offences relating to pollution and odour incidents at Truro Crown Court.

It also admitted causing two serious incidents that devastated the local river ecosystem.

In August 2016, a powerful biocide used to clean the wastewater tanks and pipework was released, killing thousands of fish over a 2km stretch of river.

It also pleased guilty to releasing quantities of suspended solids in August 2018, coating a 5km stretch of the River Inny in black sludge.

Dairy Crest further admitted failing to notify the Environment Agency within 24 hours when things had gone significantly wrong on seven occasions.

Handing the company a £1.52 million fine on Thursday, Judge Simon Carr sitting at Truro Crown Court said there was evidence of a poor management culture at the company.

Judge Carr cited evidence that those responsible for the wastewater facility felt “intimidated and bullied” by their line manager.

“This meant they felt unable to come forward with concerns as they would be personally criticised when limits were exceeded or missed,” he said.

In one incident, an employee filmed a wastewater monitor that has been removed from an effluent tank and placed in a bucket of clean water, in order to hide breaches of the plant’s discharge permits.

Judge Carr further found that one of the serious breaches that resulted in ecosystem damage was “as a result of one of the employees placing material in one of the tanks that was entirely unsuitable and unauthorised”.

But he added: “Having read the documentation with care, it appears this was not a widespread or systemic problem, (but) it was an issue that should have been addressed sooner by senior management.”

Judge Carr added that the issues had persisted for many years and “blighted the lives of those that lived nearby”.

“On occasions it was so bad that people who lived locally were unable to leave their houses,” he said.

“While there is no evidence that the discharges actually presented a risk to health, those living nearby knew they were smelling foul discharge from a substantial commercial concern and were undoubtedly concerned about the impact on health as well as their quality of life.”

The company was ordered to pay the full fine within 28 days, and the court heard that it previously agreed to pay court costs of £273,000.

Helen Dobby, area director of the Environment Agency, said: “As a large and well-established operator, Dairy Crest Limited should be up to the job of maintaining the required environmental standards.

“Instead, it has over a period of many years failed to comply with its environmental permit and not been able to protect local people and the environment.”

She added: “We acknowledge that Dairy Crest Limited has been taking steps to remedy the various problems, but unfortunately these actions were not swift enough on many occasions and proved to be ineffective in stopping pollution.”

The company said: “Once again, the company would like to express its sincere apologies to those who have been affected.

“Considerable work has been undertaken to rectify the historic issues to which the prosecution related.”

It continued: “The company continues to invest significant resources in the best technology, processes and people to further improve its environmental performance and minimise its impact on the local community.

“As the largest employer in north Cornwall, the company remains committed to supporting its local communities and becoming a better neighbour.”