Marton water supply: Rangitīkei District Council opts for new approach

The trial treatment plant at the Tūtaenui Reservoir Reserve was deemed too expensive and complex to run long term. Photo / Fin Ocheduszko Brown

The future of a Rangitīkei town’s water supply has taken a new direction, after mixed testing results were revealed.

Rangitīkei District Council decided in a public-excluded meeting on April 9 to pursue an alternative approach to fixing Marton’s water issues.

Marton has had water quality problems for years with high levels of manganese (a common mineral) and geosmin (produced by algae) in its surrounding water.

A trial treatment plant was set up last year using a nanofiltration system.

Despite “promising” testing results last November, the council has switched to a new approach to improve water quality sooner, while a long-term solution is developed.

After further testing and an independent review, the council found it would be too expensive and complex to run long term.

“Knowing what we know now, it would not be fiscally responsible to move ahead with that option given the cost implications for our ratepayers,” Deputy Mayor Dave Wilson said.

“We know residents are frustrated and have been waiting years, even decades, for improvements, but this testing work has allowed us to build a full picture of our options and make decisions based on evidence.

“The last thing we want to do is replace one version of sub-par water with another.”

The council trialled a nanofiltration system. Photo / Rangitīkei District Council

The council said the new approach aimed to improve water quality in the short to medium term, while longer-term planning continued.

It consists of three components:

• Installing ultrasonic algae control systems in the Tūtaenui Reservoir Dams to manage algae blooms during warmer months
• Constructing a special treatment plant at the Calico Line bore to improve groundwater quality from that bore
• Blending water from the reservoir dams with water from the Tūtaenui bores during peak demand.

The cost for the alternative approach will be covered by the existing Marton Water Strategy budget.

So far, $3.8 million has been spent from the $11m project budget.

Arno Benadie, the council’s deputy chief executive and assets and infrastructure group manager, said none of Marton’s existing water sources were “straightforward”.

“Dam water can be difficult to treat consistently, while groundwater in this part of the country contains high quantities of minerals like calcium, manganese and iron that require more advanced treatment,” Benadie said.

Wilson said the alternative approach reflected how much had been learned through the project so far.

“I’ve said from the start we need to test, test, test. This is a significant investment for our community and we need to be confident in the decisions we make,” he said.

“We’ve gained a huge amount of knowledge about Marton’s water - what works, what doesn’t and what’s possible.

“Importantly, we now have options available to us that weren’t on the table when we started this work in 2019. That puts us in a stronger position to deliver both immediate improvements and a long-term solution.”

The council said it would provide updates as the short-term solution was finalised.

Fin Ocheduszko Brown is a multimedia journalist based in Whanganui.