On July 1, the fares for state ferry trips to Penobscot Bay Islands will jump 10 percent, which isn’t so bad considering the price of diesel fuel has doubled in the past two years.

“We’ve held off to see if we could weather the storm, but we can’t,” said Jim MacLeod, in charge of ferries for the Department of Transportation. He said only two people attended a public hearing May 15 in Rockland. One of them was a reporter, the other a ferry user who supported the rate hike. Fares will generally rise by 50 cents to $2. Passengers pay half the cost of operating the ferry through fares; the other half is paid by the state through gasoline tax revenue.

In 2004, the fuel budget for ferries to Vinalhaven, North Haven, Matinicus, Islesboro, Swans Island and Frenchboro totaled $535,000. MacLeod is now looking at $1 million for diesel fuel. Although he likes the idea of alternatives, at this point he can’t think of any. Biodiesel would be better for the environment but would end up costing more, he said. MacLeod has heard the complaint that the state subsidizes islanders by paying for half of the ferry service. He points out that mainland residents drive on roads that are heavily subsidized, and sees no difference between that service and the ferries. If a private company tried to provide ferry service, fares would have to double to break even.

At the nonprofit Casco Bay Lines, general manager Pat Christian said he anticipates a $40,000 shortfall in revenue this year because of budget-busting fuel prices. He said diesel fuel varies from $1.75 to $2.20 per gallon, and he can’t lock in the price with a contract as he did in the past. The ferry service burns 250,000 gallons of oil per year. “It’s really tight,” said the veteran of 22 years with Casco Bay Lines. He is a former bus company manager who grew up in the Blue Ridge Mountains of Virginia.

Christian hopes Casco Bay’s ferries will prove an attractive alternative to more expensive trips for local people as well as tourists from elsewhere. Casco Bay earns 60 percent of its revenue during the summer months. The Casco Bay fleet is now equipped with modern, fuel-efficient diesel engines. But when costs double, that’s trouble. The corporation’s board of trustees will mull a possible rate increase, he said.