There were more than 11,000 fly-tipping incidents on public land in Norfolk in 2020/21 - but landowners say that is just the tip of the iceberg.
The County Land and Business Association (CLA) in the East of England said fly-tipping remains a "constant menace", as government statistics revealed an increase in the county.
Cases on public land went up from 10,353 between April 2019 to March 2020 to 11,265 from April last year to March this year.
But the CLA, which represents farmer, landowners and rural businesses, said the statistics are only half the story.
The organisation says they do not include fly-tipping on private land, so thousands of incidents, blighting rural communities, are not included.
Norwich had the most fly-tipping incidents in 2020/21 with 4,755 incidents, although that was a drop on the 4,937 over the previous 12 months.
Great Yarmouth had 2,146, up on 1,491, while King's Lynn's 1,188 was down on 1,261.
Breckland was up from 984 to 1,103 and South Norfolk increased from 725 to 971.
Broadland was up from 438 to 629, but North Norfolk fell from 517 to 473.
CLA East regional director Cath Crowther said: "Fly-tipping remains a constant menace and a crime that continues to take place with worrying regularity.
“The statistics released today don’t include figures for incidents of fly-tipping on private land which the landowner, who is a victim of crime, has to clear at personal cost or risk prosecution themselves.
“Clearing waste on private land comes at significant personal cost to a landowner and can average around a thousand pounds per incident.
"Many areas are targeted on a regular basis so this cost soon adds up to a significant amount.
"There simply won’t be a reduction in this crime until those caught are given much tougher punishments. In many cases this is serious organised crime, and should be treated as such."
Councils in Norfolk have been cracking down on fly-tipping, with West Norfolk Council among those which have stepped up investigations.
Breckland District Council has issued a number of fines for dumping waste, including for one fly-tipper who made it easy for the council to catch him - he left his name and address among the rubbish he dumped.
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