An Oamaru man was fined $200 for dumping a plastic drum on the beach near Caledonian Rd, Oamaru, on Monday.
The 21-year-old was confronted by a witness at the time and collected his rubbish.
Waitaki District Council community services group manager Dr Thunes Cloete said the cost to ratepayers of illegal rubbish dumping - for the disposal of the rubbish and staff time - was estimated to be $30,000 a year.
"Illegal dumping of rubbish occurs on a regular basis. However, we're often notified after the fact and it is difficult to identify the offender. We have issued four infringement notices over the past 12 months,'' he said.
He urged those who saw illegal dumping to contact the council "as soon as possible with as many details as possible'', including the location, time, type of rubbish, any vehicle registration numbers and a description of those involved.
"We do, however, ask that witnesses take care and approach anyone with caution. While we appreciate the vigilance of community-minded people, we do not want to see anyone come to harm.''