Thrillseekers sliding down a concrete spillway at a northern New South Wales dam are risking their lives in front of audiences of millions.

Videos of young people on the giant "illegal waterslide" at the Tweed's Clarrie Hall Dam have been viewed up to seven million times.

One video shared this week has attracted more than three million views and includes subtitles that insinuate the people featured have been given permission to slide.

However, the Tweed Shire Council's manager of water, Anthony Burnham, said the council would never give permission because of the serious risks involved with a flip-bucket at the bottom of the chute.

"It's got a large flip bucket at the end which is an energy dissipating device and with any significant flow you can be held underwater in that flip bucket and drowned, obviously on the way down you can be rendered unconscious and drown," Mr Burnham said.

Surfing down the spillway at Clarrie Hill Dam has gained notoriety online. ( YouTube )

Mr Burnham said the council was considering its options to stop the practice, which has been exacerbated by social media.

"We've tried to have these things removed from social media channels with limited success, things like CCTV monitoring and the like have also been vandalised so it's been very hard for us to try and keep people away," he said.

Mr Burnham said an extreme measure could be closing the Clarrie Hall Dam to the public.

"Council might have to consider it as an option to close the dam to the public altogether," Mr Burnham said.

Clarrie Hall Dam, in northern NSW, could soon be closed to the public. ( YouTube: )

Daredevils turn to YouTube

Managing director of Safe on Social Media Kirra Pendergast said the appeal of risk-taking behaviour for adolescents was often increased by the potential audiences reached through platforms like YouTube.

"There is a massive upsurge in it, every second child in every primary school I speak in wants to start their own YouTube channel and the more dramatic the content the more views they're going to get," she said.

"It gives them their instant fame hit, the riskier the behaviour the more fame they get, it's like a drug."

She said the monetisation of social media content was also attractive to young people.

"There's a massive financial incentive because once you hit 10,000 views on YouTube they start to place ads around your videos so it can be quite a good earner," she said.

"If a video had roughly 3.5 million views a year, they would make roughly between $8,000 and $10,000."