This story was updated at 3:40 p.m. EST.

Hundreds of seasonal park rangers could be caught in a de facto hiring freeze next summer if the National Park Service's budget sustains even deeper cuts to reduce the national deficit, warns a new report from the National Parks Conservation Association.

Additional cuts also means fewer staff to respond to emergencies, protect natural and cultural resources, provide educational programs and maintain campgrounds and trails, according to the report "Made In America: Investing in National Parks for Our Heritage and Our Economy."

The report, issued in advance of a deadline for a congressional "supercommitee" blueprint that seeks to reduce the national deficit by $1.5 trillion over the next decade, is aimed at pressuring Congress to preserve federal spending for parks.

"We are increasingly concerned national parks are at a tipping point and the Congress and administration need to pay attention," said Craig Obey, NPCA senior vice president of government affairs during a press call with reporters this afternoon.

A new report from the National Parks Conservation Association warns that deeper cuts in the National Park Service's budget could significantly erode the agency's ability to provide services, including at sites like the Blue Ridge Parkway in Virginia. Photo courtesy of Virginia Department of Conservation & Recreation.

The Budget Control Act of 2011 requires the bipartisan committee to find ways to shave the $14.9 trillion deficit. But if Congress fails to act by end of the year, automatic across-the-board cuts are supposed to kick in that could result in a 9 percent reduction in the NPS budget.

"What this means is during the busy season, when American families and international visitors are looking forward to their park vacations, there are less people to guide hikes, provide campfire talks or simply to replace the toilet paper in the bathrooms," said John Garder, the budget and appropriations legislative representative for NPCA, said of the report's findings.

Even more modest reductions "would be deeply damaging," added Garder, who spent the better part of a year analyzing NPS budget data and interviewing park, tourism and economic experts about the current and potential impacts of reduced budgets on the system.

National parks are already operating with a more than half-a-billion-dollar annual shortfall, meaning many staff positions remain vacant and priorities go unfunded. For example, 10 years ago, the Blue Ridge Parkway that runs along the Appalachian Mountains, had 240 permanent rangers to manage the 469-mile park. Today, the Park Service can afford to fill 170 of those positions.

A 5 percent cut to the Blue Ridge Parkway's $16.3 million budget would mean a $815,000 reduction, which is more than the park spends on seasonal rangers, according to the report, and the park would likely have to shorten hours or close visitor centers. A larger cut would almost certainly mean layoffs of permanent employees and no seasonal hires, the report concludes.

Most of a park's budget is spent on fixed costs, such as fuel, rent, utilities and benefits for permanent employees, Garder said. So even a flat budget would reduce the amount of discretionary spending available for seasonal rangers, brochures and toilet paper because prices for fixed cost items continue to increase.

"Park superintendents, their greatest flexibility is hiring more or less seasonals," said Denis Galvin, former NPS deputy director. "A nine percent cut would essentially wipe out seasonal hires … and result in park closures shortly after that."

The situation is not just contained to the Appalachian parks. The number of seasonal and permanent rangers nationwide is down 17 and 23 percent from 1980, respectively, even though park visitation has increased by 60 million people and numerous units have been added to the system.

The report presents case studies of potential budget cut effects on 12 parks that reflect the diversity of resources within the system. It also seeks to remind decisionmakers what a large impact the parks have on the economy with minimal investment.

For example, the Park Service's $2.6 billion budget is a miniscule one-thirteenth of 1 percent of the total federal budget. Yet parks produce a total of 270,000 private-sector jobs and generate $13.2 billion in direct economic activity.

"Investing in national parks does not just protect nature and the opportunity to educate current and future generations about our natural and cultural history, it's also an investment in a valuable economic asset," Garder said.

National parks account for eight of the top 25 travel destinations in the United States, according to Forbes, providing affordable vacations for American families and attracting millions of international tourists. If visitors arrive to find programs canceled, facilities unclean or closed, the results would be disastrous to the local economies that depend on them, said Iliff McMahan, former mayor of Cocke County, Tenn., which includes part of the Great Smokey Mountains National Park. Visitors who have a bad experience will go home and tell their friends that it was not worth it, he said.

"They'll never come again and neither will their friends," McMahan said, imploring lawmakers to recognize national parks are an investment in the economic engine for many communities.

In some of the darkest times in the nation's history, leaders have created and funded national parks. "The question is," Garder said, "now, will we as decisionmakers, as a nation, continue to make national parks a priority?"

Click here to read the report.