Robert Long, author of A Life on Gorge River, and his wife, Catherine Stewart, author of A Wife on Gorge River, emailed the Otago Daily Times from their home on the coast south of Jackson Bay.
''It is inconceivable that any Fiordland, Mt Aspiring or South Westland Department of Conservation administration worth its salt could possibly allow such a destructive intrusion to occur on their watch,'' the email said.
The couple considered the region through which the Westland District Council's property company is proposing to have a toll road built is already accessed by thousands of ''resourceful, motivated people'' by foot, boat or air.
''These are some of the best outdoor experiences available in the world. They are well rewarded for the extra effort or expense.
''The rest of the travelling, exploring public should not be able to once again intrude upon and destroy the special reward that is already available to any motivated person.''
The couple believed if the road followed the coast it would ''potentially wipe out'' crested penguin colonies and damage ancient Maori archaeological sites.
An inland route would have a similar effect on other wildlife.
''These places are treasures beyond material value or gain.''
Council-owned Westland District Property Ltd announced last year it had a memorandum of understanding with an overseas company that wants to build the toll road.
Asked to comment on the concerns of Mr Long and Ms Stewart, property company chairman Durham Havill said he would not be responding to individuals but was engaged in discussions with councils, government departments and other organisations.
