North Yorkshire County Council could approve a 600,000 cut to its 6.5m subsidy of bus services at a meeting next week.
The Yorkshire Dales Society said much of the coast as well as the Yorkshire Dales and North York Moors National Parks would become inaccessible to people without a car on Sundays and Bank Holidays, in what it called a "devastating blow" to the region's tourism industry if the changes go ahead.
Commuters, shift workers and pensioners in outlying villages would also be among those affected by cuts to about 30 bus services, including withdrawing evening services.
Chairman Colin Speakman said they were concerned that there had been no change to the original proposals, despite hundreds of objections. The council's transport scrutiny committee has already recommended the changes are given the go-ahead.
Mr Speakman said: "The Executive is being advised that there is no viable alternative to making these cuts, but this is clearly not the case. There has been no feedback or discussion of these cuts by officers with stakeholders, nor apparently with the majority of county councillors, many of whom were objectors to the proposals."
Among the services facing the axe is the DalesBus network, run by the society's subsidiary company, the Dales & Bowland CIC. The society said a grant of 52,000 would keep the core network to Malhamdale, Wharfedale, Nidderdale, Wensleydale and Swaledale going.
Coun John Blackie, who represents the Upper Dales division on the county council, said communication between the county council and councillors had been poor.
He said: "It's always a question that there's a small number of people who are going to be very severely affected by any changes to services, that's what a rural county is all about, and these people's lifestyles, the way they go about their business can be completely changed by a decision that appears to be small beer, but is not to them."
Coun David Jeffels, chairman of the transport scrutiny committee, said they had been anxious to ensure daytime services were preserved because they were vital to ensure people could go to work, shopping and hospitals.