In 1916, President Woodrow Wilson signed an act calling for national parks to remain "unimpaired for the enjoyment of future generations."

More than a century later, environmentalists are accusing the Trump administration of violating that act by allowing parks to remain open during the government shutdown.

With the shutdown already shattering records as the longest in US history, national parks have felt the absence of around 21,000 furloughed employees.

An estimated 3,3000 park workers have stayed on to provide essential services such as law enforcement and emergency medical attention.

This under staffing has incited chaos in a number of parks across the country.

Though some public land remains in pristine condition thanks to respectful visitors and local volunteers, other areas face long-term environmental damage and threats to visitor safety as the shutdown wears on. In some cases, the damage could last for years.

Almost immediately after the shutdown went into effect on December 22, park visitors began to uncover piles of haphazardly discarded trash, including soiled diapers, alcohol bottles, and discarded shotgun shells.

Restrooms began overflowing with human waste, and garbage was found scattered along major highways.

At Joshua Tree National Park in Southern California, visitors took to defacing rocks with graffiti and cutting down trees that have been around for centuries. Some even skirted entrance fees, which are supposed to go toward visitor services.

A few parks, like Yosemite, were able to handle the situation relatively quickly.

"The first week was like the wild west and people did whatever they wanted," said John Tillison, a retired park ranger.

Two weeks later, he found portable outhouses and members of the Yosemite Climbing Association handing out litter grabbers, gloves, and garbage bags. The group asked visitors to return the garbage they had collected and offered to dispose of it for free.

Tillison said he collected only half a trash bag worth of garbage, since the park "looked pretty good."

That's not the case everywhere.

In the midst of the shutdown, the National Parks Conservation Association (NPCA) has compiled a list of parks with the most egregious conditions, including the Sagamore Hill National Historic Site – the former home of Theodore Roosevelt – which recently saw a fire in its visitor center.

The situation is "becoming a crisis," said John Garder, the senior director of budget and appropriations at the NPCA. "There is, at this point, a threat of long-term damage that could last years, if not decades."

In some cases, he said, the damage can be irreparable.

According to Garder, the nightmare scenario that would require national parks to close has already arrived in certain areas.

There's a financial toll to keeping parks open

During prior government shutdowns, administrations have suspended all operations at parks, including visitor access. In an unorthodox move, the Trump administration has opted to leave gates open to the public.

The NPCA called the decision "reckless" and "illegal," arguing that it violates at least four separate provisions of federal law.

The NPS has responded to concerns by diverting visitor fees toward park maintenance, allowing additional staffers to clean restrooms, patrol the parks, and pick up trash.

While the decision may help to keep parks cleaner, it could also be causing them to lose money.

According to the NPCA, national parks collect around US$400,000 in fee revenue on an average day. Since the start of the shutdown, the group estimates, the NPS has lost more than US$6 million in fee revenue. That's on top of a US$11.6 billion backlog on much-needed repairs.

"In robbing those accounts, they are undermining projects that superintendents and partner groups have been counting on – sometimes for years," said Garder. "It essentially pulls the rug out from under them."

Though keeping the parks open could ensure that visitors and tourists continue to pump money into the local economy, Garder said the long-term effects could be far more destructive.

"In cases where parks are partially open, it is an invitation for visitors to be at greater risk…and for resources to be damaged," he said.

Understaffing could pose a safety threat

In the first sixteen days of the shutdown, at least seven deaths were reported in national parks – but the link between the deaths and understaffing is tenuous.

A spokesperson for the NPS told The Washington Post that an average of six people die in national parks each week due to "accidents like drownings, falls, and motor vehicle crashes and medical related incidents such as heart attacks."

With so many park rangers off-duty, it's possible that more accidents could occur.

On Christmas Day, a man at Yosemite died of a head injury after what was likely a short fall. A witness told The Post that the emergency personnel who arrived on the scene didn't have a stretcher.

The man also had a dog with him, which violates federal regulations. A senior NPS official told The Post that rangers frequently intervene when they see someone walking a dog.

At the time, the paper reported that only six rangers were available to monitor conditions at Yosemite, whose land is roughly the size of Rhode Island.

There's also the danger of crumbling infrastructure whose maintenance has been put on hold.

"There are visitor centres in disrepair, roads that are falling apart, trails that need stabilisation, [and] water systems that are at risk of breaking down," said Garder.

Without the funds to address these issues, he said, "it will eventually create some threats to visitors' [safety]."

Visitors are endangering trees and wildlife

Visitors aren't the only concern. The absence of park rangers makes it difficult to police human activity that endangers wildlife.

At the Great Smoky Mountains National Park on the border of North Carolina and Tennessee, at least three black bears have been poached since the start of the shutdown.

Littering also poses a severe hazard. When humans leave their food lying around or pile it into overflowing trash cans, bears can grow accustomed to eating it. This causes them to lose their fear of humans and potentially attack.

Some visitors have also sent out drones that can harm local birds.

On January 2, Pinnacles National Park in Central California learned of a visitor who was using an unauthorised drone to harass a California condor, according to a report given to Business Insider by the NPCA.

Of particular concern, said Garder, is the damage done to Joshua trees.

The towering species is more than a namesake for a national park. It's also a key part of the Southern California ecosystem, providing vital support to birds, bats, and insects, among other forms of wildlife.

"When a mature [Joshua] tree is cut down, an ancient organism has been killed, and it could be centuries before another takes its place," a director at the Mojave Desert Land Trust told the Desert Sun.

During the shutdown, there have been at least three reported cases of the trees being cut down at Joshua Tree National Park as visitors tried to off-road in restricted zones.

These actions propelled the park to announce a closure on January 8, but it later rescinded the plan, saying it would use park revenue to stay open.

Rangers and conservationists agree: parks should close

While the sum of this damage already constitutes an emergency, it's difficult to predict what could happen next.

"The parks service won't have a full sense of the damage until they're able to get back on duty," said Garder.

"We expect they will find more vandalism and other significant damage to sensitive ecosystems."

That's assuming park rangers will resume their positions after the shutdown – a possibility that, for some, has faded further from view.

By week three of the shutdown, some rangers had already secured second jobs while others were considering filing for unemployment. President Trump has suggested that the shutdown could last "months or even years."

"I really love my job and I would do everything I could to come back to it…but I've got to eat," said a National Park Service employee at a park in the Southwest, who wished to remain anonymous so she could speak frankly.

"Everybody's really tired of riding the roller coaster," said Tillison. "There's a lot of frustration, and rightfully so."

While most parks have managed to avoid shutting down entirely, many have closed their campgrounds due to health and safety concerns. Both the NPCA and park rangers agree that the solution would be to close the parks for the remainder of the shutdown.

"It's gotten to the point where businesses and people and communities surrounding parks are now urging that parks be closed," Garner said.

"They understand that our parks are not just for short-term gain. They are for long-term preservation and the enjoyment of the American people."

This article was originally published by Business Insider.

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