It's been two years since the last Glastonbury music festival was held in rural western England, but scientists say the event, which is usually held annually, has a lasting effect on the area's wildlife. 

The levels of cocaine and MDMA (ecstasy) detected in a river running through the site were so high wildlife living downstream could be caused significant harm, according to researchers.

"Unfortunately, Glastonbury Festival's close proximity to a river results in any drugs released by festival attendees having little time to degrade in the soil before entering the fragile freshwater ecosystem," said Dan Aberg, a postgraduate student at Bangor University in Wales. 

Samples were taken by the Bangor team in 2019, both before and after 200,000 people flocked to Worthy Farm in Somerset to see Stormzy, The Killers and The Cure headline the festival. 

Ecstasy levels in the local groundwater and rivers were four times higher the week after the festival.

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High levels of cocaine in particular can interfere with the life cycles of small animals, including a protected species of European eel that calls the area home. 

Aberg added there was no doubt the festival was the source of "illicit drug release."

In response to the findings, Glastonbury's organizers have repeated their request for partygoers to use the toilets provided – as urination on the site is thought to be how most drugs find their way into the ecosystem. 

Aberg's colleague Christian Dunn said the contamination was far from a laughing matter and its impact on wildlife is "hidden, worryingly understudied, yet potentially devastating."

But it's not just rural eels in England's southwest that are suffering – their urban counterparts are also facing drug-related issues. According to the London Wildlife Trust, cocaine in the River Thames is "just another thing" the struggling population now has to deal with.