The National Park Service raised eyebrows this week with a plan to more than double, and in some cases nearly triple, entrance fees at the nation's most popular national parks.

The new changes would affect 17 national parks and potentially bring in an additional $70 million a year, according to the Park Service, which says the increases are necessary to address the $11.3 billion maintenance backlog in the federal parks.

At a rate of $70 million a year it would take more than 161 years for that extra annual revenue to wipe out the entire $11.3 billion backlog — to say nothing of the maintenance needs that would arise between now and then. On top of that, the fees would offset less than one-quarter of the $297 million Park Service budget cut proposed by the Trump administration.

At Grand Canyon and Yellowstone national parks the price of a single-vehicle pass would rise from $30 to $70 during peak season from May through September. Parks such as Arches and Canyonlands in Utah, and Shenandoah in Virginia, would have their peak rates rise from $25 to $70.

Those increases would apply to weekly entrance fees at those parks. Rocky Mountain National Park is the only park on the list also offering a one-day pass, which a spokesman for the Park Service told the Denver Post would no longer be available during peak season.

The proposed increases are drastic. The last time the Park Service raised entry fees, in 2015, vehicle entrance fees increased from $25 to $30 at the nation's 10 most popular parks.

“The infrastructure of our national parks is aging and in need of renovation and restoration,” Interior Secretary Ryan Zinke said in a statement. “Targeted fee increases at some of our most-visited parks will help ensure that they are protected and preserved in perpetuity.”

Others say that fee hikes are no substitute for more federal funding, especially given Zinke's proposed cuts.

“Given the scale of the backlog, fees alone cannot be the answer to this enormous challenge,” the National Parks Conservation Association, an independent group working to protect national parks, said in a statement.

The association says that the chief challenge facing the Park Service is dwindling money from Congress. In raw-dollar terms the agency's budget has been more or less flat over the past decade. But as a share of total federal spending, the amount of money appropriated for the National Park Service has fallen by a third since 2005.

Over the same time period, the annual number of visitors to the park system surged by more than 20 percent, from 273 million in 2005 to 331 million in 2016. It's little wonder that the agency can't keep up with maintenance costs.

Doubling entrance fees during peak seasons could lead some potential park visitors to stay home instead. “High entry fees will shut the public out of our parks,” the Sierra Club said in a statement. Research has shown that entrance fees are associated with “significant but small” drops in park attendance. The effect of more than doubling park entrance fees is not known.

A spokesman for the Park Service downplayed the concern that raising fees would reduce visitor numbers at some parks. “That is not the intention of this proposal, and we don’t have any estimates to suggest that would be the case,” Jeremy Barnum said.

The Park Service is accepting public comment on the fee proposal until Nov. 23. The fee increases would take effect in 2018.