Treated sewage flowing into Queenstown rivers from faulty system

Wednesday, 22 January 2025

Treated sewage from a faulty system has been flowing into Queenstown rivers, leading some councillors to call for a pause on all development until the issue is resolved.

However, the Queenstown Lakes District Council says that could take five years and cost millions of dollars.

Queenstown sewage is treated at the Shotover Wastewater Treatment Plant, situated on the delta at the confluence of the Shotover and Kawarau rivers.

The treated wastewater is captured in a “dose and drain” disposal field where it is supposed to soak into the ground prior to entering groundwater and the Kawarau River.

But the system is faulty, resulting in two abatement notices and 10 infringement notices from the Otago Regional Council related to incidents at the site since 2021 – including five this month.

In a statement, the district council said the treatment plant was modern and performing well but the disposal field had experienced performance issues.

There had been persistent ponding and periodic spillover of treated water into the Kawarau River.

“The treated water is not soaking into the ground at the rate it was designed to,” the council noted in an unattributed statement.

A 2021 abatement notice included evidence that there was ponding at the disposal field and that the district council had not reported it.

The 2024 notice detailed several incidents including untreated wastewater being discharged to the field and treated, and untreated wastewater flowing into the Kawarau River.

At that time, testing showed “extremely high levels” of E coli and “total suspended solids”.

The statement said the council had now allocated $77.5 million in its Long Term Plan to develop and implement a new disposal strategy, but an alternative system was likely to take “some years”.

However, deputy mayor Quentin Smith has questioned how the system could deal with the thousands of new houses anticipated in the town, when it was not coping now.

A pause in residential and commercial development would ensure the problem was not exacerbated further, he said

It was part of a wider infrastructure deficit that included major transport problems and water issues, he said.

The council had not clearly explained the issues or how they would be resolved, he said.

“I think that’s causing a huge part of the angst. I don’t think [the] council have taken it seriously enough. We need to take it seriously.”

Queenstown-based Otago Regional councillor Alexa Forbes, a former chairperson of the district council’s infrastructure committee, also wanted answers.

“I want to know why the disposal field isn’t working, or is it the entire plant that’s not working?

“If the entire system isn’t working, we’ve got real trouble.”

Queenstown-based news site Crux has doggedly pursued both councils over the concerns, publishing photos showing pipes discharging treated waste into the Kawarau River and claims that solid waste was blocking the disposal site.

If the treatment plant was operating properly there should be no human waste reaching the disposal field, Forbes said.

Recent regional council testing showed that wastewater going into the Kawarau River was “highly treated”, with very little E coli, but there was not supposed to be any wastewater going into the river, she said.

“That is a delta of majestic South Island rivers – the Shotover and the Kawarau.

“There’s a conservation order on the Kawarau River and yet there’s a pipe going in there with water flowing directly into it.

“I think we have to be very careful in prioritising economic development – which in Queenstown generally means more houses, more connections, more visitors – over environmental requirements.”

The district council’s earlier statement said it undertook regular testing and reporting on the treated water quality to the regional council.

There had been “considerable investment” in the treatment facility in the past 10 years, and construction of a second process treatment train at the plant was under way.

Before 2019, the treated water was discharged directly to the Shotover River, in accordance with the consent conditions of the time.

An earlier regional council statement said it had an investigation under way, which was expected to conclude soon.

“We cannot release further specific details at present because if further action were to proceed, current information could potentially become evidence.”