Interior Secretary Ryan Zinke wants to attack the National Park Service's staggering maintenance backlog by significantly raising entrance fees at 17 national parks, but the calculations the Park Service uses to distribute such revenues could further dilute the impact of the not-quite $70 million a year the secretary believes the move would generate.

Under current guidelines, 80 percent of fees taken in at a park's entrance gates stay at that park, while 20 percent goes back to Washington, D.C., to be redistributed to other needy parks, most of which don't charge any entrance fee.

The fee proposal laid out last week in a press release said that, "entrance fees would be established at 17 national parks. The peak season for each park would be defined as its busiest contiguous five-month period of visitation."

During the peak season, the release explained, a seven-day-long "entrance fee would be $70 per private, non-commercial vehicle, $50 per motorcycle, and $30 per person on bike or foot. A park-specific annual pass for any of the 17 parks would be available for $75."

Currently, a pass for a week's entrance to Yellowstone National Park for a private vehicle is $30, so the secretary's plan would more than double that cost.

If Secretary Zinke saw his plan put into force, and it raised nearly $70 million a year, theoretically 20 percent -- $14 million -- would be available to be redistributed to less fortunate parks to help address their maintenance needs. But it's not that simple, said Emily Douce, director of budget and appropriations with the National Parks Conservation Association's government affairs staff. How that 20 percent typically is distributed is "complicated," she said.

"It’s intended to go to the non-fee collecting parks and those parks that collect less than $500,000, but there are exceptions," she said Wednesday. "In more detail, the 20 percent money is divided into three pots: 1) to regions (prioritize non-fee collecting parks and those that collect less than $500,000, but fee collecting parks can benefit); 2) regional Public Land Corps efforts; 3) nationwide for regions, programs, and parks to compete for (prioritize non-fee collecting parks and those that collect less than $500,000, but fee collecting parks can benefit)."

Even if the distribution was simply across the board to the 400 parks that would not see significant entrance fee increases under Secretary Zinke's plan, that would send but $35,000 to each of the parks.

At Devils Postpile National Monument in California, $35,000 would trim its December 2016 maintenance backlog from$1,144,654 to $1,109,654. At Fort Pulaski National Monument in Georgia, which charges visitors $7 for seven days, $35,000 would cut its $19,102,109 maintenance backlog (pre-Hurricane Irma), to $19,067,109. At the Little Bighorn Battlefield National Monument in Montana, $35,000 would slice the $9,536,847 maintenance backlog to $9,501,847.

Of course, if people simply avoided the higher fees by purchasing an $80 America the Beautiful - 2017 National Parks Annual Pass‎ through the mail, they'd get a better deal, as those passes are good for a full year and allow unlimited entrances into parks that charge entrance fees. But if folks purchased that pass at one of the other public lands agencies, such as the U.S. Bureau of Land Management or the U.S. Forest Service, or through the mail, that would greatly reduce the revenues Secretary Zinke's plan envisions for the Park Service.