Glastonbury Festival has admitted breaching environmental regulations after human waste from the site polluted a nearby stream.
The incident happened after a steel tank used to store human sewage from festival-goers sprung a leak during the event in June 2014.
A “large quantity” of sewage filtered into Whitelake River, causing harm to fish and water quality, a district judge was told.
Sensors in the stream alerted the Environment Agency, which is now prosecuting the festival, that ammonia levels had increased.
South Somerset and Mendip Magistrates’ Court in Yeovil heard a number of fish - including protected brown trout – died as a result.
Glastonbury Festival 2014 disputes this but admitted the single charge against it, accepting that “significant” harm was caused.
Festival founder Michael Eavis, dressed in a smart pinstripe suit, appeared at the court along with Christopher Edwards, the operations director.
The charge states the festival caused “a water discharge activity not under or in accordance with an environmental permit, namely the discharge of human sewage derived from the Glastonbury music festival. contrary to regulations 12(1)(b) and 38(1)(a) of the Environmental Permitting (England and Wales) Regulations 2010.”
District Judge David Taylor adjourned proceedings for a Newton hearing to decide the facts of the case before sentencing.
Prosecuting, Kieran Martyn told the court: ``The charge involves the music festival Glastonbury Festival in 2014.
“The festival has taken place over several decades now. In 2014 the population of the festival was in the region of 170,000 people – about the size of the city of Peterborough.
“Obviously the festival takes place in the middle of the countryside. It doesn’t have the sewage infrastructure of Peterborough.
“The management of waste produced by the festival is quite an issue. There are a series of systems that manage it.”
Mr Martyn said the festival uses three very large steel tanks, one of which is located on a nearby dairy farm.
“In 2014 the tank sprung a leak in one of the joins between the steel plates and the base of the tank,” Mr Martyn said.
“Around June 28, that leak developed and allowed a very large quantity of sewage to get into a farm ditch and from there into the Whitelake River.
“It caused significant harm to both the fish and the water quality.”
Mr Martyn alleged that the festival had failed to test the tank and monitor it properly in the lead up to the incident.
“The impact was extensive,” he added. “It extended for at least 4km downstream.
“In relation to fish, there was a significant fish kill. There is a dispute about the assessment of the fish kill.
“The fish that were killed included brown trout, which has protected status.”
Mr Martyn said the offending was at category one, meaning a fine between £55,000 to £300,000 was appropriate.
The turnover of the festival that year was about £37 million, he added.
Representing the festival, Kerry Gwyther said an environmental report found the stream had a history of being of a ``poor quality''.
Of the 42 dead fish, 39 were recorded downstream and only 10 of these were brown trout, he said.
There was no post-mortem testing of the fish to establish the cause of their deaths, Mr Gwyther added.
“We don’t accept that it was a major incident as described by the agency,” he said.
“The leak period was eight hours. We do accept that there was a significant affect on water quality and the fish health.
“Significant costs were not incurred in terms of a clean up.”
Mr Gwyther described the leak as “very small” and said the manufacturer and installer could not understand how it occurred.
“It is traditionally used by the farm throughout the whole of the year to store waste from animals,” he said.
“The manufacturer says that the shelf life of the tank is 50 years. This was a tank that had been in use for five years.
“As far as the manufacturer is concerned, this is a freak incident. The other tanks which Glastonbury use have never had a problem.”
Mr Gwyther told the court the tank had been cleaned and inspected before the incident.
In terms of the sentencing fine, he said: “It is a little known fact that its net profit last year was £84,000 before tax and a similar figure for that year.
“That’s because of the huge amount of money that Glastonbury donates.”
He said the site donated £2m in 2015 to a number of charities, including the Somerset Wildlife Trust and WaterAid.
The judge said: “There are significant differences between one account to another.”
The Newton hearing to decide the facts is expected to last for four days.
Environmental experts are due to give evidence at that hearing, as well as the tank’s manufacturer and installer.
Speaking outside court, Mr Eavis apologised for the incident.
“We did something wrong, we had a faulty tank,” he said.
“Of course, I’m exceedingly sorry for what’s happened.
“All that stuff in the river, you get thorough problems and we don’t set out to affect the water quality of the river.
“We’re on the opposite side of the debate – we’re trying to save the environment, we’re trying to protect all of the species – so obviously I’m very sorry for what’s happened.”