Officials have reassured the public that although the source of a high bacterial count in Lake Dunstan's Kawarau arm at the end of the year had yet to be identified, there was no risk to swimmers or to the town's drinking water supply.
Asked yesterday about the incident, Central Otago District Council water services manager Russell Bond said water-quality monitoring of the Kawarau arm was carried out this summer as part of the Cromwell wastewater resource consent.
One round of results at the end of December showed a high number of bacteria in the main channel of the Kawarau arm, but the results for local beaches were low and met safe swimming standards, he said.
''The samples showed that this did not come from the Cromwell wastewater plant but from further up the catchment.''
Re-testing was done at the original site - the Bannockburn inlet- and extra samples were taken upstream of the Bannockburn bridge for a week, finishing last Monday.
Those results were all normal, Mr Bond said.
''... we have not been able to identify the source.''
The Otago Regional Council and Public Health South had been notified.
The district council had referred the matter to the regional council's pollution team for further investigation.
Mr Bond said there had been no risk to Cromwell's water supply, which came from a bore on the shores of the Clutha River arm of Lake Dunstan, upstream of the Kawarau confluence.
