Marton water's taste and odour issues caused by algae and seasonal 'turnover'

Marton's water supply comes from a floating intake in the Tutaenui Reservoir. Photo / Laurel Stowell

Algae in the Tutaenui Dam has caused an unusual taste and odour in the Marton water supply over the past few days.

However, the water remains safe to drink, Rangitīkei District Council operations manager Andrew van Bussel says.

"We've got a full, conventional treatment plant which is fully compliant, and the drinking water is also fully compliant," van Bussel said.

"It has to meet all the standards otherwise we get into a fair bit of hot water, so to speak."

Van Bussel said the council dosed activated carbon into the water supply to "absorb some of that taste and odour issue" and had adjusted the doses again after complaints from the public were made.

"We will probably add some carbon to our filters as well as our clarifiers.

"What happens at this time of the year is that the dam changes temperature, and it has a little bit of what they call a 'turnover', so there's possibly something like that happening at the moment."

"We're monitoring it, and we're monitoring our algae levels to see where they're sitting.

"The water is very safe to drink, there's no two ways about it."

According to envirolink.govt.nz a "turnover" refers to the "mixing phase" of an artificial lake "at the end of a stratified period, be it temperature-driven or driven by a wind-mixing event".

Van Bussel said the council's water strategy involved "possibly moving away from that dam water".

"We've adjusted our doses and our PH a little bit, and we've adjusted where we're taking our water from in the dam. We have a floating intake, so we can find where our best water is.

"You can't make too many adjustments all together, because then you don't know what's fixed what.

"There's two and a half days' storage in the reservoir as well, so it takes some time to work through that tank as well."

In 2019 the Rangitīkei District Council installed a filtered water tap at the Marton War Memorial Hall on Wellington Rd after the town's ongoing water issues. It remains free for the community to use.