WASHINGTON – The Bush administration has ordered America’s national parks to show that they can function at 80 percent or less of their operating budgets, and that’s forcing some parks to cut services for visitors as summer approaches.

National Park Service officials said the initiative was an effort to cope with the rising costs of salaries, utilities and other management expenses without harming the parks’ “core” missions of protecting the nation’s natural treasures and enabling visitors to enjoy them. The Park Service has more than 270 million visitors annually.

But park officials in the field said the initiative was forcing “gut-wrenching” decisions that visitors would notice. At many parks, volunteers will take on larger roles, and there’ll be fewer interpretive ranger programs, the officials said.

At Glacier National Park in Montana, three campgrounds no longer will have potable water or trash service this summer.

“We have high ideals here,” said Stephanie Dubois, the deputy superintendent of Glacier. “We know how to provide top-quality service. It’s a very difficult decision every time you take a step backward from what you’ve been doing.”

In the future, Glacier officials are considering raising backcountry and campground fees, Dubois said.

At Rocky Mountain National Park in Colorado, one of the park’s six visitor centers was closed and two water stations were shuttered as a result of the initiative.

Kyle Patterson, a park spokeswoman, said the decisions prompted “soul-searching,” but that one of the park’s most popular visitor centers was able to stay open another four hours a day thanks to the money saved by closing a less-used one. No one’s complained about the closed center or the water stations, Patterson said.

President Bush is proposing to cut another $100.5 million from the national parks’ $2.1 billion budget next year. According to a report this month by the Government Accountability Office, the parks have an estimated $5 billion maintenance backlog, and even before the cost-cutting began, many of them had moved from slashing back-office operations to trimming visitor services.

At the same time, the parks are facing rising costs. Payroll, utilities, fleet and other fixed operating costs have increased yearly. Pay raises alone have been about 4 percent a year. At Grand Teton National Park in Wyoming, utility costs increased 46 percent from 2003 to 2005.

If the financial pressures continue to grow, the parks will have no choice but to cut more services, reduce access for visitors or rely more on private dollars. The Park Service receives as much as $250 million a year from fees, donations and concession royalties.

Twelve parks in the West began the 80 percent budget process, known as “core operations analysis,” last year. All the national parks are expected to complete it by 2011.

“This isn’t about giving up 20 percent of your resources,” said David Barna, a Park Service spokesman. “It’s … making sure the mission comes first. They’ll continue to have the resources they have.”

Park Service officials stress cuts in areas such as administrative jobs, which most visitors wouldn’t see.

“We don’t see this as a budget exercise,” Barna said. “It’s about management excellence.”

Tony Schetzsle, the superintendent of Canyonlands National Park in Utah, called the initiative “necessary for a better idea of what we can do and what we can sustain. … In terms of costs vs. income, we were headed for financial implosion.”

“We had to do something,” Schetzsle said.

“We support looking at ways to become efficient,” said Blake Selzer, the legislative director of the National Parks Conservation Association, an independent advocacy group for the national park system.

“But … not as a justification for an insufficient budget request. Do we really want our Park Service to be the bare minimum? Out of respect for our national treasures, we’d argue not,” Selzer said.

“If you’re looking to trim it back to 80 percent of current funding, you’re going to go below core operations,” said Bill Wade, the chairman of the executive council of the Coalition of National Park Service Retirees, a group of former high-level employees.

Parks entrusted with cultural and historic resources would be especially hard-hit, Wade said.

“If you can’t care for historical records, structures, artifacts – once they deteriorate, they’re no longer historically accurate,” Wade said.

Gettysburg National Military Park in Pennsylvania, which just began its “core operations” analysis, no longer has a historic architect and a monument preservationist, said Katie Lawhon, the park’s spokeswoman. The park has 1,300 monuments and 148 historic structures.

“We’re already extremely efficient,” Lawhon said. “As we talked about stopping doing things that don’t contribute to our core mission, there wasn’t anything that we immediately thought of. … All the easy fruit’s already been picked.”