(TNS) — WASHINGTON — When John Muir helped establish the National Park Service, he argued that such parks were vital to help people unplug from the world. “Break clear away, once in a while, and climb a mountain or spend a week in the woods,” Muir was quoted as saying in 1915.

But these days at Yosemite National Park, hikers to Half Dome are likely to encounter people talking on cellphones as they climb to the top. For visitors to the parks, the call of the outdoors increasingly comes with crisp 4G service, and not everyone is wild about that.

In Yosemite, Yellowstone, Mount Rainier and other iconic parks, environmentalists are pressing the National Park Service to slow or halt construction of new cellular towers within park boundaries. They say the NPS is quietly facilitating a digital transformation with little public input or regard to its mission statement — to preserve “unimpaired the natural and cultural resources and values of the National Park System.”

Richard Louv, author of several books on connecting young people with the outdoors, said the parks are losing what once made them unique.

“Can you imagine hiking in Yosemite far from other people, and then suddenly it sounds like you are in McDonald’s, with everyone on their phones?” said Louv, author of “Last Child in the Woods” and other books. “That is not why most people go to our national parks.”

Yet advocates for increased cell service, including many NPS officials, say the parks can’t cling to an earlier era. Expanded cellular and broadband coverage, they argue, helps rescue teams respond to emergencies and are necessary to draw a new generation to the parks.

“Visitors want to be able to use their mobile devices to share experiences with their friends and family,” said Lena McDowall, an NPS deputy director, in testimony to a U.S. Senate subcommittee in September. “They want to take advantage of the many internet-based resources we have developed.”

Locked in competition, Verizon, AT&T and other telecom companies are aggressively courting the most popular national parks, and under the federal Telecommunications Act of 1996, the parks are obligated to at least review proposals for new cellular towers. Yet because the National Park Service is highly decentralized, NPS headquarters does not track construction of cellular towers in parks nationwide. Nor has it developed a national policy to guide parks superintendents in reviewing such proposals.

Yosemite has one park that has come under scrutiny for its expansion of cell service. In October, using public records request, the watchdog group Public Employees for Environmental Responsibility found that Yosemite has quietly approved six cellular towers in the park.

PEER, which has asked the Interior Department’s Inspector General to investigate, said that Yosemite is in “violation of both federal laws and agency policies” by approving the towers without public notice or environmental review. The group also unearthed emails that suggest that Yosemite officials are uncertain about ownership of five of the towers and how revenues should be handled when telecom companies co-locate on the towers.

In an email, Yosemite spokesman Scott Gediman said he was aware of PEER’s complaint, but could not immediately comment. Jeffrey Olson, a spokesman for NPS headquarters in Washington, also declined to discuss the Yosemite case, other than to note that “decisions about cell towers and coverage are up the (park) superintendents.”

Juggling public demands has always been difficult in the national parks, especially those that draw big crowds and include large expanses of designated wilderness. In 2016, the NPS reported a record 331 million visits to the parks, many of which suffer from overcrowding in the summer.

For the last year, Mount Rainier National Park in Washington state has been weighing whether to allow three telecom companies to co-locate a cellular facility at the park’s Paradise visitor center.

Public opinion appears divided on the plan, which would extend cell service to some, but not all, of the mountain. Of those who commented on the proposal, 249 were supportive and 241 were opposed.

In North Dakota, wilderness advocates strongly opposed Verizon’s plan to build a new cell tower at Theodore Roosevelt National Park, fearing it would blanket the backcountry with cell signals. NPS officials ultimately decided to design the new cell tower so it would not extend service into the park’s designated wilderness.

Heidi Flato, a spokeswoman with Verizon, said the company is aware that some wilderness advocates have concerns with expanded cell coverage. “We’ve always sought to work with the National Park Service to find the right balance,” said Flato, noting that a major complaint of park visitors is being unable to get a signal.

Over the last decade, PEER has emerged as the fiercest opponent of telecom expansion in Yosemite, Yellowstone and other national parks. The nonprofit group is led by lawyer Jeff Ruch, who keeps a close eye on the special use permits the national parks issues for new services and concessions.

Under National Park Service guidelines, such “special uses” are encouraged if they enhance park resources or improve public safety. But such uses should be rejected, the NPS says, if they “unreasonably disrupt the atmosphere of peace and tranquility of wilderness.”

Ruch argues the park service rarely grapples with these tradeoffs when it is approached by cellular providers. “A telecom company will come to a park and say, “Nice mountain. We want to put a cell tower on it.’ And the park usually says yes.”

U.S. Rep. Jared Huffman, a Democrat who represents the north coast of California, said he doesn’t support physical construction of cell towers in wilderness areas. But he sees no problem with telecom companies improving signal strength near visitor centers, park entrances and even into the back country.

Huffman has introduced legislation, The Public Lands Telecommunications Act, that would allow parks and federal land agencies to keep the rental income they receive from granting right-of-way to cellular towers. They then could use that money to partner with nearby rural communities on improving their cellular and broadband service.

PEER opposes the legislation, arguing it would create incentives for more construction of cell towers on public lands. But Huffman said that districts like his, with remote communities scattered amid a patchwork of federal lands, need help in improving communications, partly for public safety reasons.

“This shouldn’t be an issue,” said Huffman. “If you want to avoid distractions in the wilderness, you can just turn off your phone. But you might also want to be able to turn on that phone and make a call if you broke your arm and needed help.”

First responders and other safety officials agree that enhanced cell service helps in many outdoor rescues. But the issue is complicated, said Derek Newbern, a spokesman for King County Explorer Search and Rescue in Washington state.

Telecom companies, he said, can only go so far in expanding cell coverage to wilderness areas, because of lack of roads and electrical transmission lines. And yet when many people go into the back country, they often assume they will continue to have a cell signal, creating a false sense of security.

In August, hundreds of rescuers spent days trying to locate a lost hiker at Mount Teneriffe, a 4,787-foot-high mountain east of Seattle. The hiker initially had cell service, then lost it and wandered before a search helicopter rescued her four days later.

Newbern said he advises adventurers to carry personal locator beacons or a more recent innovation, satellite messengers, in case they get in trouble.

“People will go into the backcountry and think the cellphone will be their savior,” said Newbern. “Sometimes it doesn’t turn out that way.”

©2017 McClatchy Washington Bureaun Distributed by Tribune Content Agency, LLC.