More than three years after a massive pile of recycled glass was illegally dumped outside Canberra, it still hasn't been cleaned up.

Thousands of tonnes of the material were hauled out of the ACT by a contractor in 2014, and authorities are yet to explain why it never made it to a waste recycling plant.

In August, the Canberra contractor who dumped the glass at a property near Lake George promised he would clean it up, but the glass is still there - and Bywong locals are concerned it could make its way into their water, along with plastic and other rubbish caught up in the pile.

The local council has since dropped legal action on the dump, saying it didn't think it was fair to spend public money on a clean-up likely to cost more than the value of the land the glass is sitting on.

Chris Berry, director of planning at Yass Valley Council, said councillors went out fairly regularly to inspect the glass and check "it hasn't shifted". From such inspections, as well as consultation with the Environmental Protection Authority, they had decided the dump posed no significant environmental or health risk.

"It hasn't been crushed so fine it's going to wash into waterways, there is some drainage through the property, but if it was moving, we would have noticed," Mr Berry said.

"It's an eyesore, though."

It is understood the contractor had since declared bankruptcy, and the owners of the property could not afford the clean-up bill.

A paper prepared for the Yass Valley council in 2016 identified the glass as coming from Canberra and said "collaborative work by council staff, the NSW and ACT branches of the EPA stopped any further material from being released from the ACT".

"We stepped in and were able to stop any more coming," Mr Berry said.

While a number of locals said the council had "failed to intervene" when they first reported trucks rolling into the area to dump the glass, many also pointed fingers at the ACT government.

The contractor who dumped the glass previously said he was paid to take the recycling off another company, which had a contract with the ACT government.

A Transport Canberra and City Services spokesman was not able to confirm this but denied having a financial relationship with the contractor in 2014-15.

"The issue remains the jurisdictional responsibility of NSW authorities," the spokesman said.

Local Roger Melton said he had hounded ACT authorities for answers but had been stonewalled.

"The silence has been deafening," he said. "It's their glass, their contract, [surely] they're responsible," he said.

"Our community, like other areas around the ACT, is becoming a dumping ground."

Glen Toskin is president of Geary's Gap & District Community Association, which he said "basically formed in response to the glass" and "the lack of response" from the council.

"It's time something was done, you can't have people coming down from Canberra trashing the place," he said.

Mr Berry said the council did not have the resources to take the matter further with the ACT government.

A cross-border program to address illegal dumping, which was funded by the NSW government four years ago, had helped the council shut down some other illegal dump sites in the area, and tighten laws, he said.

While the committee was no longer funded for aerial surveillance, cooperation between NSW and ACT authorities, as well as councils near the border, continued.

Mr Berry confirmed ACT building waste was also regularly dumped at another property off Hadlow Drive, in excess of permit conditions.

"That's a bit of a different situation though because they do have a permit and we're working with the people involved."

Mr Melton said NSW landowners around the capital should "band together" to take their concerns directly to the ACT government.

In 2015, the contractor who dumped the glass lodged a development application to build a recycling facility at the site, but this was later withdrawn.