To help tackle billions in deferred maintenance projects, the National Park Service is proposing a massive increase in entrance fees during peak visitation season for 17 parks, including four of Utah’s Mighty Five.

The seasonal cost of admission would rise to $70 per vehicle at Bryce Canyon, Zion, Arches and Canyonlands national parks under the proposal outlined Tuesday.

“As part of our commitment to improve the visitor experience and ensure America’s national parks are protected in perpetuity, we are considering increases to fees at 17 highly visited national parks during peak visitor seasons,” NPS officials wrote in a statement Tuesday.

The new fee schedule would charge $50 per motorcycle and $30 per person not in a personal vehicle. Fees would also increase for commercial tour operators.

The park service is accepting public comment until Nov. 23. As of Tuesday evening, the comment site did not appear to be working.

“The fees are being raised for a good reason,” said Zion National Park spokesman John Marciano. “This is a proposal for a fee structure increase, and your comments that you can make are extremely valuable to us.”

The fee hike would more than double the present price of admission, which is $30 per vehicle, $25 per motorcycle and $15 per individual at Zion and Bryce Canyon, and $25 per vehicle, $15 per motorcycle and $10 per individual at Arches and Canyonlands.

The park system’s maintenance backlog was $11.3 billion last year. Utah’s share of that backlog was $278 million in 2015 — $62.1 million at Zion — much of that needed for road repairs.

Park service officials estimate that the fee hike will produce $68.6 million in added revenue in its first year.

Under the Federal Lands Recreational Enhancement Act, parks keep 80 percent of the revenue collected at their gates. The remaining 20 percent goes to support other national parks; 118 of the system’s 417 locations charge entrance fees.

The price hikes would go into effect in 2018. They would apply to visitors May through September at the four largest Utah parks, as well as Denali, Glacier, Grand Canyon, Grand Teton, Olympic, Sequoia & Kings Canyon, Yellowstone and Yosemite national parks.

That window misses two of Zion’s and Arches’ busiest months, April and October.

The price of admission would rise from June through October at Acadia, Mount Rainier, Rocky Mountain and Shenandoah national parks, and from January through May at Joshua Tree National Park.

It is possible the proposed fee restructuring could hurt certain parks because a seasonal fee of $70 per vehicle could make buying the systemwide $80 annual pass a popular option for most people planning to visit one of the 17 parks. The price of that annual pass does not change under the NPS’s new proposal.

Because 80 percent of the money paid for an annual pass stays with the park where it was purchased, some parks could miss out on the hoped-for new revenue. Visitors touring the Colorado Plateau, for example, could buy the pass at their first fee-charging park, such as Colorado National Monument or Petrified Forest National Park, then get into Utah parks for free.

For park-specific annual passes, the price would rise to $75 under the proposal. The current price is $50 at Zion, Arches and Canyonlands, and $35 at Bryce Canyon.

It’s also not clear how the fee plans might affect proposals to manage visitation at Zion and Arches, where the park service is considering reservation systems. If fewer guests are allowed into the parks or are encouraged to visit during the offseason, it could affect potential revenue gains from a fee hike during peak months.

David Nimkin, Southwest regional director for the National Parks Conservation Association, said the maintenance backlog is an acute issue for parks, but he doesn’t believe tapping visitors’ wallets is the best way to address it.

In a statement, association president Theresa Pierno said, “We should not increase fees to such a degree as to make these places — protected for all Americans to experience — unaffordable for some families to visit.”

The association supports the proposed National Parks Legacy Act, which would commit a share of oil and gas revenue to pay down deferred maintenance over the next 30 years

“We advocate using offshore royalties, which would be allowed under [the] bipartisan [proposal],” Nimkin said. “It makes sense to do it that way because it’s big money and it’s reliable money.”

Earlier this year, President Donald Trump’s administration proposed $400 million in cuts to the National Park Service for 2018.

“It would be helpful for this administration to support this legislation and not assume that increased fees will make a dent in this backlog. That is particularly true with a proposed 13 percent budget cut and eliminating over 1,200 permanent jobs,” Nimkin said.

Rep. Mia Love, R-Utah, says she is “quite concerned that the proposed fee increase would make [parks] inaccessible to many Utah families.”

“I look forward to working closely with the Department of Interior to find solutions that keep these lands financially accessible to every Utah family,” said a Tuesday night news release from her office.

The fee restructuring would also affect tour providers, but the proposal does not indicate how much their fees would rise.

In the Zion gateway town of Springdale, clients pay the park fee separately from charges from operators such as of Zion Adventure Company. It serves tens of thousands of customers a year with guiding and shuttle services and gear rentals.

“That impact will still be on our customers,” said Bill Dunn, manager of the company, which pays a flat fee for special permit to guide in Zion. “It’s unknown what, if any, increase on that permit will be. The question we have to wonder is, have they considered the financial impacts on the communities surrounding the park? And the bigger concern will be the impact on the visitor-use management plan.”