The council admitted one charge, brought by the ORC in August last year, laid under the Resource Management Act, and has been fined $37,500 by Judge Brian Dwyer.
The offence carried a maximum penalty of $600,000.
Mr Boult said yesterday he would have preferred a collaborative approach to the issue.
"I was disappointed the ORC chose to pursue this through the court.
‘‘In the spirit of co-operation, working together, we could have improved in this area."
The council would "take a learning" from the incident and it should be more proactive, but said the incident was a symptom of the infrastructure challenges the council was facing.
Judge Dwyer’s sentencing notes said a jet-boat driver on the Kawarau River smelled sewage on February 20, 2017. It was also detected and reported by another person.
The following day, the jet-boat driver could still smell it, so investigated and found discoloured water entering the river, and "solids and particles floating in the water".
The sewage was entering the river through a council stormwater pipe, which discharged it down a bank to the river.
Judge Dwyer said a blockage had been caused by an accumulation of fat in the drain and it appeared the wastewater system had been "deliberately designed and constructed" by the council so any wastewater overflow would go in to the stormwater system.
Over the two days about 43cum was discharged.
A swimming hole in the river, about 50m downstream from the point of discharge, was found to have 3.6 times more faecal coliforms than guideline levels, presenting a risk to swimmers and recreational users, while 589m downstream total coliforms still exceeded guideline levels.
The site was disinfected, but wastewater sludge and residue — sewage, toilet paper and "other products" — remained on the riverbank site, between the end of the pipe and river, until it was removed in May.
Judge Dwyer said the three-month delay "shows a very casual attitude to this incident".
Judge Dwyer did not allow the council any credit for the remedial measures it was undertaking, considering that was counterbalanced because the council had a "poor past history", having received four infringement notices for wastewater discharges.
He said "some portion" of the fine might properly be directed to an environmental project or organisation in the Queenstown area — the amount and to whom would be chosen by the regional council.
