New protozoa barriers will be installed at both Ranfurly and Patearoa water supplies later this year.

The news comes just days after Naseby and Ranfurly were on urgent water restrictions, after heavy rain caused two separate incidents affecting both its supplies.

On January 25, the council issued a conserve water notice following a significant break in the Hawkdun Irrigation Race that supplied raw water to the Naseby plant for treatment.

Contractors worked all through the weekend and early into this week to fix the damage.

A dirty river in Ranfurly after heavy rain last weekend. SUPPLIED.

Meanwhile on Monday afternoon Ranfurly residents were also issued with urgent water restrictions after the dirty river conditions limited the council’s ability to treat the source to safe levels.

Instead the town had instead been operating off stored water, with residents given a total ban on outdoor water use, along with four minute showers only and limiting dishwasher and washing machine use.

The new $3million treatment solutions, approved by the Central Otago District Council on Wednesday, would solve the water turbidity issues both Ranfurly and Patearoa were prone to.

The Ranfurly and Patearoa treatment plants sourced their water from ‘surface water sources’ — the East Ewe Burn and Sowburn River. 

Capital projects programme manager Patrick Keenan said during high turbidity events, both towns’ drinking water had occasionally been non-compliant, leading to boil water notices.

Additionally, both treatment plants needed upgrades to meet the requirements of the New Zealand Drinking Water Standards.

In October 2023, the council received direction from the government’s water services regulator Taumata Arowai regarding compliance deadlines for protozoa barriers to be installed in all water systems.

Protozoa barriers mitigate parasites, such as cryptosporidium, entering the water supply system. 

The installation of those barriers was part of a New Zealand-wide strategy to improve water safety and prevent waterborne illnesses which could cause significant health issues. 

When protozoa was effectively removed or inactivated, the risk of outbreaks such as the one in Queenstown in September 2023, was substantially reduced.

“Currently chlorination occurs which treats bacteria, and ultraviolet light treatment needs to be added to provide treatment for protozoa, a class of parasitic microorganisms that can cause acute gastrointestinal illness,” Patrick said.

The upgrades to the water treatment plants should be completed by the end of 2025 as required by Taumata Arowai.

“While water conservation may still be necessary during high turbidity events, we are confident that our solution — chlorination, with the additional combination of cartridge filters and ultraviolet treatment — is an affordable and effective option to meet New Zealand’s Drinking Water Standards.”

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