Westpower's estimated $100 million hydro scheme on the Waitaha River in Westland has been backed by both Development West Coast and Westland Mayor Bruce Smith for its economic spin-offs for the region.

Development West Coast bosses and the mayor spoke yesterday during day two of the Hokitika hearing, sparked after a flood of more than 3000 opposing submissions.

However, Mr Smith said he supported both Westpower's application and the Minister of Conservation's intention to grant a concession to construct and operate a hydro scheme on the Waitaha River, south of the town of Ross.

He said Westpower was a 100 per cent community-owned company, meaning that all benefits would accrue to the Westland community.

Development West Coast's chief executive Chris Mackenzie and chief operating officer Warren Gilbertson, said it was not often the West Coast saw projects of this magnitude.

It was estimated at between $80m and $100m and of that, 75 per cent or $64m, would stay on the Coast.

Mr Smith said employment would increase and the economy would be boosted during the three-year construction period.

The West Coast's security of supply would also improve.

"When the Alpine Fault shifts this station has a good chance of being the main source of supply on the Coast and its industry for weeks and maybe months."

The project was sustainable and built around a renewable resource, he said.

"I would ask the Department of Conservation to remember this is a run of the river plant, not a dam. Its peak output is between 16MW and 20MW.

"The powerhouse is located on river flats just below the Morgan Gorge and this is conservation estate, it's actually stewardship land which we say should be in the hands of the local people.

"It was never considered to have significant environmental value at the time the Department of Conservation was established in the late 1980s."

However, the area is regarded as one of the best whitewater runs in the world by kayakers.

Whitewater NZ representative Doug Rankin and competitive whitewater kayaker Trent Garanham, on its behalf, said the gorge was considered the 'Mt Cook' of descents among kayakers.

"In my opinion the Waitaha is the premier whitewater run in New Zealand ... and one of the best in the world."

The river as a whole offered the highest quality of whitewater.

Mr Garanham was part of the three person team to complete the first descent of the Morgan Gorge in 2010.

It was estimated 20 kayakers had tackled it since.

The hydro scheme was initially opposed by kayakers who were bolstered by Forest and Bird and the Green Party.

In opening the hearing on Monday, Department of Conservation statutory manager Dave Newey, said DOC had received 3264 submissions on the proposal. That included 2864 Forest and Bird template submissions and a Green Party submission with 2343 signatures.

Clare Backes, on behalf of the West Coast branch of the Green Party, said it fully supported the generation of energy using renewable sources, but detrimental environmental effects must be weighed against the benefits of the power generation.

"And in this case the detrimental effects on the environment far outweigh the befits of power being produced."

There was no proven need for power to be generated from the Waitaha River, she said.

It was also surprising that Westpower was proceeding with the scheme

"The department received the application in 2014, but this scheme has been under development for up to eight years, during which time power usage has stabilised on the Coast to the extent that Trustpower do not consider it economically viable to expand their hydro scheme on the Arnold (River).

"Essentially we think Westpower's thinking is out of date."

Ms Backes said the area had to be conserved purely because of its high natural values.

Mr Mackenzie said they wanted a balance between future opportunities for the West Coast and the "uniqueness" of the environment.

"These recreational users are important as well but we've got to make sure that we don't think this is the only place where there's that type of rapids that you can go canoeing down."

The Department of Conservation has approved in principal the application for a concession for a run-of-the river scheme that does not involve damming the river. A weir and diversion structure will be constructed at the upstream end of Morgan Gorge.

A 2km access road, powerhouse and tunnel will also be built.

- Hokitika Guardian