Old town infrastructure has been partly blamed for water discharge and take non-compliance which has caused environmental effects.
The Otago Regional Council's compliance monitoring report for 2013-14 showed 22% of those who hold consents for water discharges and takes received grade four or five non-compliance rating where environmental effects were observed.
Problems found included poor performance of effluent systems, poor effluent quality from commercial wastewater systems and poor effluent quality from industrial discharges.
Cr Bryan Scott asked at a committee meeting last week if the high figure indicated there was a problem in that area.
Council director Jeff Donaldson said issues such as the Queenstown Lakes District Council's issues with infrastructure failure which led to sewage spills to water had contributed to the figure.
There were also some incidents where waste from industry ended up in streams.
A major problem was the old infrastructure in places like Dunedin, where it was hard to track down the sources of some contamination, he said.
The Dunedin City Council did work with the regional council in those situations to search for sources.
The non-compliance was ''definitely not acceptable'' and the council worked with the region's councils, Queenstown Lakes district in particular, to help identify how to improve their management of infrastructure.
In some cases in Queenstown problems were caused by materials put down drains blocking them, he said.
Also included in the non-compliance figures in that category were offensive and objectionable odour beyond a boundary and problems with water takes.
Overall, 42.9% of consents complied with their consent conditions and 31.5% were awarded grade two or three compliance, because monitoring data was sent in late.
