Mundaring OIC John Browne said police knew of three landowners offered $2000-$3000 to allow one- to four-day events on their land.
�These organisers are claiming to have engaged with the local Shire and police, when in fact they have not,� Senior Sergeant Browne said.
�People need to be aware there are unscrupulous people out there searching for land to hold illegal gatherings in remote areas.�
A Gidgegannup owner, who asked not to be named, said he responded to a request for land on a buy and sell Facebook page.
�He seemed really professional, said he had public liability insurance and a 20-page plan covering crowd control; everything you�d need to satisfy most people,� said the landowner.
�He came to the property and loved it, he said he had contacted the police and the Shire and there would be over 400 people at the event.�
The landowner then became aware the Shire of Gingin had turned down a similar event planned for Telephone Road in Neergabby.
�I found out from police if the event got out of hand, I could be liable for thousands of dollars,� he said.
�A couple of thousand dollars in payment for use of my land no longer seemed like easy money.�
He found workers from the event had camped on his land and installed portable loos several days prior to the long weekend event.
�I hadn�t agreed to anyone camping on my land,� said the landowner.
When he returned the next day to check the workers had left, he said the area was clean but he found burnout and donut marks around the paddock.
�I think that was a sign of things to come if four lads could do that in one night; it was a bit of a wake-up call.�
The landowner cancelled the event and the organiser gave him a few hundred dollars for his trouble.
In a similar incident, a Chidlow farmer, who also asked to remain anonymous, said one of her workers asked her if she was interested in having a music festival on her land.
�I was introduced to her friend and told the event had been cancelled at another venue,� said the farmer. �I was told the Shire and police would be contacted� but I never received any paperwork.
�He said you don�t require any permits, it�s a private event.�
The farmer gave the organiser a list of requirements for the event and contacted the Shire.
�I told the organiser he had misinformed me and he needed to complete an application form through the Shire.�
She said she wanted other landowners to be aware of the possible repercussions.
�I was advised my land could end up littered with syringes and broken glass.�
WA Police and local shires have extensive powers to prosecute anyone who holds an illegal party on private land.
Anyone who organises or facilitates a gathering that becomes out of control commits an offence with a maximum penalty of 12 months imprisonment.
Snr Sgt Browne said when an event was declared out of control, police could seek reparation costs from the organisers.
�These people may say they have public liability insurance, but as with all insurance companies, look at the fine print,� Snr Sgt Browne said.
�If the organiser does not have the right approvals (from the police and the Shire) and there are issues, such as a fire or injury, the flow-on comes through the police to the insurers.�
He said insurers were unlikely to honouran illicit event, which would leave the landowner open to anyone seeking compensation.
There are numerous regulations governing liquor licensing, crowd control, traffic management, parking and evacuation plans.
Shire of Mundaring chief executive Jonathan Throssell said the Shire supported events with appropriate approvals, which �did not unduly impact the local community�.
�If an event has been held without a required planning approval, prosecution proceedings may take place against both the landowner and the event organiser,� he said.
City of Swan acting chief executive Mark Bishop said such events would require approval under the Health Act, and approval in relation to noise impact on neighbours. Event organisers for Back 2 Bassics outdoor music events refused to comment.