The flood hit halfway through the construction of the Waihou Valley flood protection scheme, which Ian had started working on in Te Aroha in 1970 as a leading hand with construction and pipe-laying experience.
"A stopbank under construction failed. It took several months of cleanup, there was trouble getting in and out of Paeroa, we had no power."
Then in 1985, another one hit. "We never thought we would get two in five years. It's a 100-year event!
"That one did devastating damage to Thames and Te Aroha. It went through Thames Hospital and the shops, blew out all the front windows. The Kauaeranga River went up 6 metres in a 12-hour period. I was just hoping it was going to stop raining.
"Three people died in Te Aroha and a young girl, a 4-year-old, got washed away and clung to debris, she was found in a willow tree. They called her the miracle baby.
"I got heavily involved in Te Aroha. I blew the reservoir up - it was full of blocked timber, trees, and they were worried it would flood the town again. I took the top level off. They were going to bring the army in and evacuate the town, but I said we could do it with our own staff. We had choppers overhead while drilling for the explosives."
It was a highlight of his career, he says. And the explosion, conducted before all the health and safety regulations of today, was successfully contained within 100m.
Things have changed a bit in Ian's time, and not just in health and safety. While he still can't sleep when there is heavy rain, telemetry and mobile phones mean he doesn't actually have to go out and about to see what's going on. "But we had more fun in the old days because of the unknown."
You don't see the impacts of flooding like that anymore, says Ian, nor are you likely to "unless there is an earthquake and it blows a bank".
All flood management assets are on a rotation of checks, maintenance and replacement, and round and round the cycle goes. But of course, there is always risk.
The Waihou Valley scheme, which had a Government subsidy of 3:1, was the biggest flood protection scheme undertaken in New Zealand and cost over $178 million. It was 26 years in the making but now helps protect valuable farmland, roads, services and communities.
Collectively, the Waihou Valley and Piako River schemes include 357km of stopbanks and floodwalls, 139 floodgates and 52 pump stations. They help protect Te Aroha, Paeroa, Thames, Ngātea, Turua and Kopu, and Ian knows all the assets quite intimately – and likes some more than others.
"The foreshore stopbanks along the Firth of Thames, if you have a full tide in a flood situation and a northerly gust, if they aren't up to scratch it's a waste of time having any of the others," says Ian, who's been involved with their top-ups three times.
The Reservoir pump in the Hauraki Plains is his "baby". Constructed in 1936, it has to be started by hand – unlike all the other automatic pumping stations – and is the only one of its kind in New Zealand. Ian has coached staff to operate the pump so "she'll be in good hands" when he leaves.
Ian, who moved to Kerepehi for two seasons to work on the scheme but stayed 46 years, says opportunities for farming, living and running a business on the Hauraki Plains would be limited if it wasn't for flood management.
"Two years ago, in January, when we had that king tide and bad weather, 1.4m of water would have gone through Ngātea. Now, you wouldn't want that in your bed, would you?
"I was talking to one of the old guys and he remembered catching flounder in the cowshed in 1938. The cows would be up to their udders in water."
But now Ian, a familiar sight driving around the Hauraki Plains in his council vehicle, is saying goodbye to managing floodwaters to spend more time with the family: "I have nine grandkids, although I'm not saying I'm going to put my feet up."
He will remain in Kerepehi – for the bowling club and the rugby club, and because he's 2m above stopbank height – and hopes "the boys" will still pop in for some brews and a barbecue, or to pick his brain.
"The boys and the gang are bloody great. You're only as good as your staff in the field - they're doing the real work, is what they tell me."
But he will not miss looking at water, he reckons.
"I have great respect for water. I've never been scared but I have worried about loss of life and getting the job done, that the pumps are working.
"I guess I'll also have to stop waving at everyone I see."
