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A recent report to the council shows in the 2017-18 year there were three prosecutions, 25 infringement fines and nine abatement notices from the council to people and businesses breaking its rules.
The number of public complaints was a record and 600 more than an average year.
Council chairman Stephen Woodhead said the low number of prosecutions was a good thing.
''I'm not happy that we have any prosecutions at all.
''I would hope that everybody complies with our policies and plans and that you don't need to get to the hard end of the process which is prosecutions.''
The number ''ebbed and flowed'' from year to year, he said.
Prosecution numbers could not be directly linked with complaints from the public, he said.
''People see bubbles in the streams, something floating on the surface in the water and call it in. It's reasonably common that there hasn't been an issue.''
However, calling these incidents in was what the council's pollution hotline was for, he said.
Council environmental monitoring and operations director Scott MacLean said investigations could determine an incident did not breach any rules or perhaps it fell outside of the council's jurisdiction.
''Multiple calls can also be received for a single incident.
''Enforcement actions undertake several considerations, such as sensitivity of the receiving environment, culpability of the offender, actual environmental impact etc.''
For less serious incidents an educational approach often had the best outcome, he said.
''Overall, we are seeing an increase in the number of incidents being reported. This may be due to lower community tolerance of perceived environmental harm, increased awareness of our pollution hotline function, an actual increase in environmental incidents or a combination of these.''