New Zealand's largest farm or massive public park? You decide.

The Department of Conservation (DOC) is open to a radical rethink of the historic Molesworth Station, the rolling high-country farm linking Marlborough to North Canterbury.

The farming lease at the 180,000-hectare cattle ranch - about the size of Stewart Island - expires in 2020, and the public could help shape its future.

STUFF Molesworth Station could be facing changes as the Department of Conservation calls for public opinion over future use.

DOC community ranger Chris Wootton said a new online survey would collect and gauge public opinion, although calls for sealed roads, tour buses and airstrips weren't likely to fly.

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"It's a fascinating time; we're looking at everything and we want as wide a range of people as possible across New Zealand to take part," Wootton said.

STUFF Visitors to Molesworth Station are only allowed access to the reserve at certain times of the year.

A management plan for the publicly-owned Molesworth was approved in 2013. Its intention was to transition Molesworth from its traditional focus on farming to include more recreation and conservation activities.

Public access to Molesworth was managed to balance recreation, farming needs, fire risk and public safety. Access was only available to the public within certain areas and on specific times of the year.

The station became a recreation reserve in 2005, but the farm's "remoteness and wildness" made it special, and different to other farm parks open to the public, Wootton said.

"It has to be balanced, but it's critical to look at a place with such high natural values at a time when tourism has boomed," he said.​

Molesworth was managed as a working high-country station through a farming lease and grazing licence to state-owned Landcorp Farming Ltd.

There were 3050 breeding cows and a further 2140 head farmed at Molesworth.

STUFF The farming lease at the 180,000-hectare Molesworth Station expires in 2020.

"The lease is due to expire and whether it gets renewed in its current form or something completely different is still to be decided.

"There is no kind of bias on DOC's part at all. If people want to open it [the reserve] up completely or shut it down, we'll look at everyone's views," Wootton said.

But any ambitious plans could have unwanted consequences for neighbouring farms.

STUFF The reserve is home to the Molesworth Run and attracts visitors from across New Zealand.

Upcot Station, in the Awatere Valley, had been in the Stevenson family for three generations. Farmer Bill Stevenson said they had been farming sheep and beef at Upcot Station "since forever".

GAYNOR JAMES/SUPPLIED Moleworth Station is a working farm as well as a reserve.

He said if the Molesworth Station was made more publicly accessible it would create an issue for stock, and a shift away from a farming focus could create wider problems.

"I reckon Molesworth is famous for its farming operation. I think taking stock off a lot of that country will be a fire hazard especially.

"Most of our stock like to be undisturbed by the public," he said.

ANDREW MACDONALD Molesworth Station faces scorching summers and freezing winters.

Originally known as Barefells Run, Molesworth Station was given its name in 1866 by John Henry Caton.

Molesworth Tour Company co-operator Lee Swift said making the station more accessible could be a mixed blessing.

"We absolutely love the Awatere Valley, and Molesworth Station. It could open up more opportunities but at the same time it could affect the tours," she said.

STUFF The Molesworth Station is a unique part of the South Island and attracts visitors from across the world.

​The survey closes on March 31. For further information and to take part in the survey visit surveymonkey.com.