Just 51 fly-tipping cases were sent to prosecutors despite almost 300,000 incidents being reported since 2019-20.
The Scottish Liberal Democrats have released figures obtained through freedom of information requests in a bid to urge ministers to introduce a restitution order.
New fly-tipping rules, which were effective from Monday, could see on-the-spot fines of up to £500 – more than double the previous £200.
But Scottish Lib Dem communities spokesman Willie Rennie said the move is not enough.
It comes as figures showed that local authorities received 284,762 reports of illegal rubbish dumping since 2019-20.
However, 51 were referred to the procurator fiscal, while 3,317 fixed penalty notices were issued.
Glasgow City Council received the highest number, with 88,357 reports across the four-year period – but just 335 fines were issued.
And cases were only passed to the procurator fiscal in seven local authorities, with convictions obtained in just two – East Dunbartonshire and North Lanarkshire.
Mr Rennie welcome the fine increase, but said Scottish Government ministers must now introduce a new rule ordering offenders to contribute to the clean-up, with the money then put towards a national fund to help farmers.
He said: “Fly-tippers are increasingly brazen. From back lanes to main roads, most communities across Scotland are blighted by other people’s rubbish.
“It’s ugly, dirty and smelly, yet only a tiny fraction of cases ever result in a fine or a trip to court.
“I am relieved that, after years of pressure from my party, the government has finally increased the level of fines available.
“However, there is still a fundamental unfairness in the system which leaves farmers and other owners with the responsibility for clearing up waste dumped on their properties.
“More needs to be done to clamp down on this disgusting behaviour and to ensure that repeat offenders feel the full force of the law.
“Alongside a robust fixed penalty system, Scottish Liberal Democrats want to see the introduction of a new restitution order, enabling the courts to require contributions from offenders to cleaning up their mess.
“These contributions could then go towards a national fund which would help support farmers and all those who bear the brunt of fly-tipping.”
The Scottish Government has been asked for comment.
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