Police say the Rainbow Serpent festival in regional Victoria was "hijacked" by organised drug syndicates.

Inspector Dan Davison said they had made a record number of arrests at the five-day Lexton event, with the majority of the 54 offenders implicated in drug possession and trafficking.

Inspector Davison said police had not previously seen illicit behaviour so blatantly on display at the event.

"The traffickers have been very overt in their actions," he said.

"Which indicates to me that the festival itself has been hijacked by potential organised crime as a platform for them to sell their wares to the vulnerable patrons that are at the festival."

He said festival organisers could not be expected to prevent the criminal activity occurring across the event.

"We've worked really strongly with the Rainbow Serpent staff and organisation, and we'll continue to do that," Inspector Davison said.

"As well run as it is, they can't gear up to tackle the sort of crime that they've seen this year, particularly in the drug space.

"Regardless of how small that syndicate may be, it's well organised — particularly given the substances we've seen coming through the event.

"We've had seizures of ketamine, MDMA, acid or LSD, cannabis as well as methamphetamine."

'Big ask' to eliminate drugs entirely

Festival organiser Tim Harvey told ABC Radio Statewide Drive that he does not deny the claims from police.

"Thirty years of prohibition has made an extremely attractive and lucrative market for organised criminals," he said.

Mr Harvey said it was obviously a concerning situation, but that it was not unique to the 18,000-person Rainbow Serpent event.

"For five days we are the largest town in western Victoria outside of Ballarat, and we will incur some of the other challenges that the rest of society faces.

"When you can't eliminate drugs from prisons and you can't eliminate drugs from the general society, it's an incredibly big ask to expect music festivals to eliminate drugs in their entirety from our grounds.

"This is happening weekend, after weekend, after weekend in every city and town across Australia."

Seven people were hospitalised for suspected drug overdoses at the site, with reports from police that a British woman is still "fighting for her life in the Austin hospital".

Mr Harvey said his thoughts were with the woman and her family.

"It's going to get worse, because the approach that has been used for the last 30 years has failed.

"It will continue to fail, and we are waiting with bated breath for governments around Australia to start to seriously work with us, and experts, to implement proper, evidence-based policy that we feel will reduce harms."

One man jailed for drug trafficking

Most of the individuals charged with drug-related offences were given cautions, but a number have already been sentenced in court.

A 23-year-old man from Edithvale in Melbourne's south-east, Kurtis Smith, broke down in tears in the Ballarat Magistrates' Court when he was jailed for three months after pleading guilty to several drug trafficking charges.

He was arrested at the event on Saturday after he was allegedly caught with 32 bags of ketamine and cocaine, 99 ecstasy tablets and other drugs.

His father cried while giving evidence in court on Tuesday when he asked the magistrate to give his son leniency.

"Every time there's a death at a music festival, I email him the article," he said.

"I hope this will be a serious wake-up call for him. He's a young man, who has his whole life ahead of him.

"He's made a mistake but I don't want it to be a lynch mob."

A 21-year-old man from Morwell in Victoria's Gippsland, Zac Mangion, was arrested by plain-clothed officers on Monday.

He was handed an 18-month Community Corrections Order after pleading guilty to one charge of drug trafficking.

His lawyer told the court he sold the rest of his two grams of ketamine he brought for personal use to another patron, for $50.

There have also been several reports of sexual assault and theft at the festival, and police and WorkSafe are still investigating a truck rollover on Thursday afternoon that injured two men and a woman in a tent.

"Potentially it was a failed handbrake — that's still a matter of investigation," Inspector Davison said.

"WorkSafe are involved because the vehicle itself belonged to the festival."

Festival has community support

Members of the community hosting the event have steadfastly defended its operation.

The Mayor of the Pyrenees Shire, Robert Vance, told ABC Radio Melbourne that drug use is a societal problem.

"It's not just a Rainbow Festival problem, it's all around the place," he said.

"I wouldn't know the counts in Melbourne every week of people that OD, but if you put 20,000 of them in an area there's a fair chance there would be more than seven that would OD.

"But because they are at a festival it becomes a highlight.

"I believe the organisers have a brilliant set-up, they have quite a large staff of medical people, I think they are doing everything they can."

Brett Leonard part-owns the pub in Lexton and says it is his "biggest week of the year".

"It helps us through the year, definitely, and they're all good people — we don't have any problems with them whatsoever."

Mr Leonard said the incidence of drug use was minimal considering the size of the festival.

"We don't think drug use is good, but out of that number, [it's] bugger all," he said.

"A nightclub in Ballarat would have a lot worse than that."