It is high on the Maungaharuru Range inland from Lake Tutira, on properties belonging to Chris Pask and Dennis and Rosemary Bell.
It is not a conventional hydro dam, but two run of river schemes. Water is borrowed and piped underground to two power stations hundreds of metres downhill before being returned to the streams.
The intake points are windswept and isolated.
"One of the things about this site is the wind - it absolutely howls through here - you can see the trees are all bent over in one direction," Mr Prater said.
He said travelling to the higher Rimu intake is referred to by workers as "going into winter".
But as quick as the wind and rain arrives it can also disappear.
"I say it's snowing and blowing and I can't get anything done in the mud, so Trustpower come down to have a look - and it's sunny. But the reality is you've got to have rain or else you don't have a hydro scheme."
Some of his workers monitor the weather more closely than others. They travel 15 minutes cross-country from rented houses near Te Pohue. When it is too wet their commute takes 90 minutes by road as they need to take the long way around because of the mud and the swollen Esk River.
In six month's time there will be little sign of the scheme, with most of it underground.
He said the many fibreglass pipes, imported from the Middle East, would be reliable for at least 50 years.
"Back in the day I used to pull out 100-year-old pipes made of wood. They had wire wrapped around them and were bitumen coated - they were still working fine."
A pond is being built at the top of one half of the scheme.
"It gives some extra capacity to generate more power at the peak times. It's generally what power stations are about nowadays because everyone gets up in the morning and wants to have their hot shower and the heater on at 7am, so the power usage spikes up - and again in the evening."
The scheme was initiated by Mr Pask about 10 years ago.
He is no stranger to historic firsts - he was first to plant vines on the Gimblett Gravels.
"Originally it started because we are quite a way up a no exit road with a long slim power line.
"The power company's had a sunset clause whereby they could cut off uneconomic lines by 2012."
Consultants said self sufficiency was viable and there was a possibility of contributing to the national grid.
He asked local power lines company Unison if it was interested but it said no.
Bay of Plenty power company Trustpower said yes.
"They are doing a magnificent job up there," Mr Pask said.
He said the hydro scheme may turn out to be only half the project.
"The cable going out to the main grid is capable of producing twice what we are making with the water.
"We haven't got a resource consent but possibly they might put in wind power to fill up the cable."
There is six year's worth of wind data from the highest ridge on Toronui Station.
"There are two test masts up there at the moment and a third going in, so it is a very strong possibility."
Mr Pask will buy electricity from Trustpower at a commercial rate and receive royalties.
"Its a pretty good scheme - it will provide all the power for the local area without pumping it in from outside Hawke's Bay."
In fact, the 3.8 MW stations will provide enough electricity to supply about 1900 households - 4000 people.
The move to smaller schemes may be an increasing trend.
Meridian Energy pulled the plug on its proposed 100mw West Coast Mokihinui hydro dam last week, as it started developing into an environmental battle.
"It's crazy pumping in power generated from places like Atiamuri when some of these small embedded generation plants can do the job without power loss," Mr Pask said.