Fly-tipped waste is discovered in Preston eight times a day on average, figures reveal.
Department for Environment, Food and Rural Affairs data shows 2,748 fly-tipping incidents were reported to Preston City Council in 2019-20 – 73 fewer than the previous year.
The Local Government Association warned that the offence costs taxpayers almost £50 million a year to clear up.
Dumped waste was found in Preston's back alleyways 1,784 times accounting for 65 per cent of incidents, 511 discoveries were made on footpaths and bridleways (19 per cent) and 441 times on roads and pavements (16 per cent).
Fly-tipped rubbish can include household waste, white goods and construction waste.
Environmental Charity Keep Britain Tidy says the crime is being driven by conmen who offer to remove household rubbish for a fee but do not dispose of it correctly.
Across England, the most common amount of rubbish dumped and reported to councils is equivalent to a small van load.
Rubbish loads of this size accounted for 34 per cent of all 976,000 fly-tipping incidents nationally last year.
Across Preston, small van loads of waste were dumped illegally on 851 occasions – 31 per cent of all reports.
A further 40 incidents saw fly-tippers discard enough rubbish to fill a tipper lorry each, costing the council £6,900 to clear.
There were also 12 incidents which required multiple loads to clear, at a cost of £2,450.
David Renard, environment spokesman for the Local Government Association, said: “Fly-tipping is inexcusable.
"It is not only an eyesore for residents, but a serious public health risk, creating pollution and attracting rats and other vermin.
“We continue to urge the Government to review sentencing guidelines for fly-tipping, so that offenders are given bigger fines for more serious offences to act as a deterrent."
He added that manufacturers should provide more take-back services so customers can hand in old goods when they buy new ones.
Preston City Council took action over 2,218 fly-tipping offences in 2019-20.
The authority undertook 829 investigations and issued 58 fixed penalty notices.
It also prosecuted three incidents in court, at a cost of £981. Such action resulted in three fines, totalling £1,110, being handed to offenders.
Allison Ogden-Newton OBE, chief executive of Keep Britain Tidy, said: “This environmental crime is being driven by ‘man with a van’ operators who are conning the public with what appears to be a cheap way of getting rid of their rubbish, but one that leads to illegal disposal and environmental devastation.
“Tragically, some businesses that hold a waste carrier licence are breaking the law and fly-tipping the rubbish that households pay them to remove.
“This must stop. We believe the only way to prevent further law-breaking is to fundamentally reform the system.
"We need tests and hurdles to ensure waste carriers are legitimate and accountable.
"Licences should be difficult to get, thoroughly checked and essential to carry out door-to-door waste collection."