SALT LAKE CITY – A series of graffiti-like paintings on rocks in national parks across the West set off a furor on social media this month, angering people who say they desecrated some of the nation’s most famously picturesque landscapes. They’ve also created a headache for park managers who have the delicate task of cleaning up the sites without causing further damage.

It won’t be easy to get rid of the paintings, photos of which were posted on Instagram and Tumblr and then picked up by hiking blogs. Sandblasting and some chemical strippers can cause even more damage to irreplaceable natural features, especially if graffiti is near ancient rock art.

In some cases, workers use plastic kitchen spatulas to painstakingly scrape off paint. Workers test different chemicals to figure out which will loosen the material without damaging rock, then rinse it off with lots of low-pressure hot water, gently scraping each layer away with the spatula, said National Park Service spokesman Jason Olson.

“They will repeat that as often as it takes until they remove all the paint or until they can’t remove any more,” he said. He said Friday he didn’t know how much it might cost to remove the paint in eight parks across California, Colorado, Utah and Oregon.

One colorful painting of a woman with blue hair at Crater Lake National Park is already covered in ice and snow and workers might not be able to reach it until next summer.

Casey Nocket, the 21-year-old suspect identified by the park service this week, allegedly used acrylic paint and signed with the handle “creepytings.”

Attempts to reach Nocket were unsuccessful. A phone listing for her was disconnected and her social media accounts have been shut down or made private.

The National Park Service said this week they’ve found paintings in Yosemite, Death Valley and Joshua Tree in California; Crater Lake in Oregon; Zion National Park and Canyonlands in Utah; and Rocky Mountain in Colorado, where Colorado National Monument was also tagged.

Zion National Park is home to red-rock bluffs, sweeping canyons – and now a backpack-sized drawing of a woman smoking on a rock near a trail named for emerald-colored pools of water.

It’s not the first time rangers have had to clean up, though paint is an unusual choice for vandals there.

Supervisory ranger Ray O’Neil said minor graffiti is scratched onto rock every day. Rangers carry nylon bristle brushes and water to brush it off as they see it.

At Joshua Tree in California, the park service has graffiti they think is from Nocket to deal with, and also a project to clean up the historic Barker Dam, which is nearly covered with scratched-on graffiti.

Rangers deal with graffiti nearly weekly there, and the most difficult material to clean off is metallic spray paint. In some cases, graffiti near ancient petroglyphs or pictographs is nearly impossible to remove and rangers have to leave it.