Friday, January 28, 2022

New research offers clarity to Timaru water issue

Council and community actions are having a positive effect on Timaru tap water, as experts work to piece together a final picture of the cause of the local water discolouration.

Following the introduction of Level 3 Water Restrictions, as well as the river engineering works in the Opihi, the majority of Timaru residents have seen an improvement in clarity of their water, Timaru District Council said in a statement today.

Council Drainage and Water Manager, Grant Hall said that a reduction in consumer demand, combined with the council’s actions, was having a positive effect on both the water colour and storage levels at the Claremont Reservoir.

“I’d like to thank the community for their patience as we deal with this issue and the great effort they’ve made so far in water conservation, the reduced demand has enabled us to minimise the use of Opihi water,” he said.

“This combined with the activities council is undertaking is beginning to show real results in the clarity of water coming out of people’s taps. If people keep up these actions this will continue to improve the situation and increase the amount of water we have on hand if we have to close off one of our sources.

“To support this, our plan to supplement the Opihi supply with water from our Temuka Reservoir has now come on stream. This will further dilute the water we’re taking from Opihi and will further improve the clarity for our end customers.”

While water staff are working on the short term discolouration issue, work to piece together the puzzle of the cause is continuing.

Analysis of the latest round of tests is offering more clarity to the likely causes of the discolouration at the source, Mr Hall said.

The results of an extended panel of tests commissioned by Timaru District Council show a higher than normal level of the mineral Manganese in the water, he said.

This mineral is often found in bore water sources, but is not usually found in significant quantities in river-sourced water supplies.

“Although elevated, the levels are still well below the maximum acceptable value for safe drinking water, so we can assure customers that although not up to our aesthetic standards, this continues to not pose any safety concerns,” said Mr Hall.

“The interactions between this, the higher levels of algae seen at the intake and our treatment methods are continuing to be investigated as the source of the discolouration.

“As we begin to learn more about the situation, and share the data with independent experts and regulatory bodies we can begin to piece together a better picture of the cause of the issue and inform any long term mitigation plans.

“While this will be useful from a long term perspective, the results also support the short term actions we’re currently taking to reduce our usage of Opihi and supplement our supply from other sources.”

The plan to deliver water into the Opihi pipeline running under the Gleniti reservoir site got underway today following construction work and testing yesterday.

A fleet of four trucks will deliver more than 1.5 million litres a day from the Temuka Reservoir to the pipeline, reducing the amount we have to take from the source as well as diluting the water being taken.

This will result increased heavy traffic movements for at least the next week around Pages, Gleniti and Mountainview Roads in Timaru and McNair Road, Richard Pearse Drive and Ewen Road in Temuka.

The issue is also proving a good testing ground for a new long term option that was considered in the Council’s Long Term Plan.

A new temporary pilot filtration plant is currently being commissioned at the Opihi water source. While only able to filter a small amount of water at a time, this plant will provide important data to inform future plans for a larger scale version at the Claremont Water Treatment Plant, Council said.

For more information about the issue and published testing results visit Timaru.govt.nz/discolouration

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