A powerful deluge on March 25 burst the banks of the Dart River, and formed a new channel, which means Kinloch Rd is now flooding more easily.
Since then, it has been closed regularly every time there is a downpour - it was impassable during teeming rain last Monday and only reopened on Wednesday afternoon after being shut for 10 days.
Uncertainty concerning the road's future is hurting tour operators and accommodation providers.
It is the only access route to New Zealand's popular Greenstone and Caples walking tracks, which link to the Routeburn Track - named one of the top 10 walks in the world.
Toni Glover, who has owned Kinloch Lodge with her husband for nearly 19 years, said the survival of her business depended on having a road open year round.
She suggested moving the road to a more sustainable spot, given it would always have the potential to flood.
"We need some certainty. We don't have a business when the road is impassable and when we don't know if people are going to turn up."
Department of Conservation figures show almost 4000 people visited the Greenstone Track last year - that is not counting visitors during the winter months.
Owner of Info & Track and Nomad Safaris David Gatward-Ferguson is having to keep an eye on the weather forecast before booking trips.
The Queenstown Lakes District Council is assuring the public the road will not be closed permanently, and it is pushing ahead with previous plans to elevate the road by 500mm.
That work will begin this month.
