Farmers have been advised to be aware of illegal waste operators who are targeting rural properties.
Natural Resources Wales (NRW) said a number of incidents occurred where farmers have been duped into deals which 'seem like a good money saver'.
A recent incident at an industrial unit near Wrexham involved a farmer accepting money to store waste on the land temporarily.
But they never returned to collect the waste leaving the farmer with a large volume of 'dangerous waste.'
Nick Thomas, North East Wales Operations Manager for NRW, said: "Landowners may let industrial units in good faith to tenants but as recent incidents have shown, there are unscrupulous operators looking to dump waste anywhere they can.
"The land owner is often left with significant quantities of waste, which is potentially damaging to the environment, and a large bill to remove it legally.
"Anyone approached to store baled or any other type of waste on their land should report it to us immediately," he said.
To provide further advice and guidance to farmers and landowners about how to comply with waste regulations, NRW has joined forces with a number of other environmental organisations on a campaign called 'right waste, right place.'
In the past, a Lincolnshire farmer faced a bill of £250,000 after he was conned into housing tonnes of waste on his land.
And farmers near Grantham were left with bills of up to £300,000 after waste was deposited on their land.
