So far, so good for the Cromwell wastewater treatment plant.
The upgrade project, which included connecting the Bannockburn wastewater system to Cromwell, was completed in November and cost ratepayers $8million.
It was the first phase of the Central Otago District Council's 10-year plan to improve the quality of the district's urban wastewater discharges.
Council major projects manager Simon Norton said the E. coli levels in Lake Dunstan had decreased dramatically - from 10,000 to two E. coli per 100ml - due to the upgrade.
"It's a major achievement.