National park visitors cut new trails in sensitive soil. They pried open gates while no one was watching. They found bathrooms locked, so they went outside. One off-roader even mowed down an iconic twisted-limbed Joshua tree in California.

During the 35-day government shutdown, some visitors at parks and other protected areas nationwide left behind messes that National Park Service officials are scrambling to clean up as they brace for the possibility of another closure ahead of the busy Presidents Day weekend this month.

Conservationists warn that damage to sensitive lands could take decades to recover. National parks already faced an estimated $12 billion maintenance backlog that now has grown.

Many parks went unstaffed during the shutdown, while others had skeleton crews with local governments and nonprofits contributing money and volunteers.

National Park Service spokesman Mike Litterst in Washington, D.C., declined to provide a full accounting of the damage at more than 400 locations, saying it was isolated and most visitors took good care of the land.

But interviews with park officials and nonprofits that help keep parks running reveal a toll from people and winter storms when workers could not make fixes quickly.

President Donald Trump has said another shutdown could start Feb. 15 if he and Democratic leaders can’t agree on funding for a U.S.-Mexico border wall, compounding pressure on the park service to catch up on repairs.

Hiring seasonal workers who typically start in the spring as rangers, fee collectors and hiking guides also has been delayed.

“We’re kind of ready to just have a bit more stability,” said Angie Richman, a spokeswoman at Arches National Park in Utah.

A colony of elephant seals took over a Northern California beach in Point Reyes National Seashore without workers to discourage the animals from congregating in the popular tourist area. Spokesman John Dell’Osso said rangers and volunteers will lead visitors on walks to see roughly 50 adult seals and 43 pups.

The Grand Canyon postponed a highly competitive lottery that provides permits for self-guided rafting trips on the Colorado River in 2020 because staff has to catch up on other work. Matt Baldwin with the river permits office said the lottery is rescheduled for Feb. 16, which could change with another shutdown. That also could lead the park to miss out on its centennial celebration Feb. 26.

At Southern California’s Joshua Tree National Park, Superintendent David Smith said officials still were assessing damage Friday but at least one signature tree died when an off-road vehicle ran it over during the shutdown. It’s not the same toppled tree from a picture distributed by the park service early in the shutdown that was used widely to illustrate the perils of understaffed or closed parks.

Park spokesman Jeremy Barnum said rangers who discovered the tree initially thought vandals destroyed it during the shutdown but that botanists later determined it fell earlier. He said the park “apologizes for any confusion this initial report may have caused.”

Smith said several other Joshua trees that can live hundreds of years were damaged, including one that was spray-painted, but the park has yet to determine the exact number and when it happened. Someone also cut down a juniper tree and off-road vehicles dug extensive wheel marks into the delicate desert soil, Smith said.

Workers at Death Valley National Park in California cleaned up 1,655 clumps of toilet paper and 429 piles of human waste as the shutdown hit during one of the busiest times of year, a park statement said Friday.

Superintendent Mike Reynolds also said that “people tried to do the right thing by leaving trash next to full dumpsters, but wind and animals dispersed it. The park’s resources, visitors and wildlife all paid the price.”

Workers have to rake and replant vegetation to repair ruts from off-road vehicles, delaying other work in the 3.4 million-acre park. Staffers spent a combined 1,500 hours this week documenting the damage, cleaning and making repairs, Reynolds said, calling the overall effects “disturbing.”

“It became pretty depressing the kinds of things people will do when they are unsupervised,” said David Blacker, executive director of the Death Valley Natural History Association.

Visitors at Arches in Utah left waste outside a restroom, stomped out five trails in a permit-only area that was shut down and damaged an entrance gate to allow vehicles to drive on snow-covered roads when the park was closed after a storm, Richman said.

People in Colorado’s Rocky Mountain National Park drove around locked gates and through meadows, spokeswoman Kyle Patterson said.

At Great Smoky Mountains National Park straddling the North Carolina-Tennessee line, visitors cut locks on some gates to closed roads and stole about $5,000 in maintenance tools, spokeswoman Dana Soehn said.

Officials at Zion National Park in Utah, Mesa Verde National Park in southwestern Colorado and Olympic National Park in Washington were fixing trails, roads and campgrounds damaged from winter storms. Mesa Verde wasn’t set to open until Monday, and some areas were still closed at Zion and Olympic.

Campgrounds, visitors centers and trails that seasonal workers help prepare could face delayed openings, and families planning spring break or summer vacations might think twice about visiting if they don’t think national parks are safe or fully staffed, said Phil Francis, chairman of the Coalition to Protect America’s National Parks.

“There are a lot of impacts that will be felt in the future that aren’t being felt or even talked about now,” he said.

Meanwhile, the prospect of another shutdown looms.

Elizabeth Jackson, a spokeswoman for Guadalupe Mountains National Park on the Texas-New Mexico border, noted the stress on workers.

“It’s a way of life if you’re a federal employee,” Jackson said. “Not to be glib, but it’s something we face every year.”