Council tipping teams are investigating a dumping mystery at Wyke, Bradford.
And officials want anyone with information about the incident to get in touch.
Large piles of what looks like piping were spotted in the area of the Judy Woods beauty spot early on Sunday.
A ward councillor has warned that a recently-introduced waste disposal permit system is encouraging fly-tipping.
A Low Moor resident was out walking when he came across the obstruction in Royds Hall Lane.
Dave McCue, of Markfield Close, alerted police after seeing the piles completely blocking the lane. He was worried that people living at Horse Close Farm would be unable to get in or out.
“I went for an early morning stroll into Judy Woods, only to be greeted by the sight,” said Mr McCue. “We contacted police but in the meantime the residents of Horse Close Farm would have had their work cut out to leave.”
Police confirmed they had been to the scene on Sunday morning and that what appeared to be piping was blocking the lane. A mattress was underneath the piles.
When fears it might be stolen cabling were unfounded, officers passed the matter on to Bradford Council.
A Council spokesman said: “We were not aware of this issue, but will send someone out to investigate as soon as we can. Obviously, we condemn these fly-tipping incidents which can be very hazardous. In the meantime, can anyone who has any information about this incident contact us on (01274) 434366.”
Wyke ward Councillor David Robinson criticised the permit scheme, brought in earlier this year and which requires people wanting to get rid of rubbish at local authority tips to have the necessary paperwork – which is free. One aim of the system was to deter people from outside the area using Bradford tipping sites.
Coun Robinson said: “I am sceptical about this permit scheme. It encourages people who can't be bothered to just dump rubbish wherever they want.
“It was supposed to put off people from elsewhere using our tips. But waste is waste, and if people take it to a proper depot, does it really matter where it is? People are not bothering to go to the trouble of getting a permit. It's easier to fly-tip.”
The Council has insisted the new scheme is working and that the amount of fly-tipped waste has fallen.