Two cross-country skiers take a break on Friday at Quarry Road Recreation Area at 300 Quarry Road in Waterville. Tests conducted by Colby College found PFAS in the snow made from water from a local stream and sprayed onto the Quarry Road trails. The research indicates that machine-made snow may be a source of human exposure to harmful industrial chemicals. Anna Chadwick/Morning Sentinel

As winters grow warmer, ski resorts are increasingly relying on machine-made snow to keep their trails open and powder-loving customers happy.

But what happens when the water used to make the snow contains forever chemicals?

New research out of Colby College indicates that machine-made snow may be a little-known source of human exposure to PFAS, a group of persistent industrial chemicals that are harmful in even trace amounts.

While no one has tested water sources or the snow at most of Maine’s ski areas, tests showed that the same chemicals found in a contaminated stream in Waterville are also present in the snow that is made from the water and sprayed onto the Quarry Road Trails, a popular municipally run Nordic skiing area.

“People have this idea that a beautiful snow-covered trail must be pristine, but there is still so much we don’t know about how forever chemicals move through our environment, about human exposure,” said associate professor Gail Carlson, who is known for her work on forever chemicals in ski wax.

Carlson’s previous research has found that ski wax containing PFAS can contaminate snow. Her newest work found that snowmaking also can carry PFAS from contaminated water sources onto the slopes, tracks and trails that we use to ski and snowshoe.

It appears that Carlson is the first to ask if the human-made snow covering Maine’s slopes, tracks and trails — the stuff shot out of mountainside cannons and inhaled by crews of trail groomers and then kicked up by skiers, snowboarders and snowshoers — has forever chemicals in it.

She doesn’t know where other Maine ski resorts get the water for snowmaking, or if any ski resorts here or across the country test snowmaking water for forever chemicals. Maine doesn’t require such testing. Carlson also doesn’t know how much of the PFAS in Quarry Road Trails’ human-made snow seeps into the ground after the melt.

Given snowmaking’s critical importance to the future of the state ski industry, Carlson would like to find out. Winter is Maine’s fastest-warming season and is now two weeks shorter and five degrees warmer than a century ago, according to a 2024 Maine Climate Council report.

Even with recent improvements in snowmaking technology, scientists predict only 15% of ski areas in northern New England and Quebec will remain viable by the end of the century under a business-as-usual warming scenario because it will only be cold enough to make snow for three weeks a ski season.

Most of Maine’s ski areas are located in the mountains and make snow from the headwaters of streams and rivers, which are not likely to be contaminated, said Dirk Gouwens, executive director of Ski Maine Association, a trade association representing most of the state’s commercial ski operations.

A snow gun sits outside the Harold Alfond Snowmaking Center at Quarry Road Recreation Area in Waterville on Friday. Anna Chadwick/Morning Sentinel

“It’s probably cleaner than most water from the tap,” Gouwens said.

As a result, most Maine resorts probably don’t test the water they use to make snow for PFAS, he said.

None of the individual alpine ski areas that are members of Ski Maine responded to a reporter’s snowmaking questions.

Some operators have disclosed their snowmaking water sources to trade publications or in their own snowmaking videos. Sugarloaf pulls from the Carrabassett River, for example. Like the vast majority of Maine water bodies, most of these snowmaking water sources have yet to be tested by state inspectors looking for PFAS.

So far, Maine has focused its PFAS testing on farms, landfills, sewer districts and public water supplies, although a small number of ponds and streams have been tested and flagged because they contain high enough levels that fish consumption should be limited or avoided.

Carlson first found perfluoroalkyl and polyfluoroalkyl substances, or PFAS, in the snow at Quarry Road Trails after Colby Carnival’s Nordic ski races in 2020. The PFAS signature matched that of fluoro waxes preferred by competitive racers seeking to reduce the friction between their skis and snow.

Carlson — whose son was a high school skier and raced on a Quarry Road Trail team — returned in 2022 to see how the fluoro wax bans, adopted in recent years by ski associations like U.S. Ski & Snowboard or International Ski Federation due to the environmental harm, affected PFAS levels.

She found 415 times less PFAS in her 2022 samples, the first tests to prove the racing bans were working.

But why was there any PFAS at all? She wondered if forever chemicals had become so pervasive that the snow falling from the sky itself was contaminated, but a backyard test at her own Waterville home found no detectable trace of any of the most common forever chemicals.

Skiers share a trail on Thursday at Quarry Road Trails in Waterville. Rich Abrahamson/Morning Sentinel

Were the college athletes cheating? Were the recreational skiers using the track on non-race days not making the switch to PFAS-free waxes? She found both scenarios improbable. The market for $100-a-tin fluoro wax had dried up after the ban, making them hard for free-spending weekend skiers to find.

It turns out the PFAS signature of the 2022 snow samples from Quarry Road Trails didn’t match that of any known fluoro wax. Instead, it matched the PFAS signature of nearby Messalonskee Stream, which is a heavily developed waterway connecting the Belgrade Lakes to the Kennebec River.

PFAS can wind up in waterways for a variety of reasons, including direct discharges from factories that use the chemicals in their manufacturing process, leaking landfills, wastewater treatment plant discharges, and runoff from nearby farms that applied sewage sludge as fertilizer to their fields.

Carlson said the source of 95% of the PFAS found in the Messalonskee comes from farm runoff tainted by sludge-based fertilizer from the Waterville sewage treatment plant that had been spread on fields for decades. That treatment plant had accepted waste from the Huhtamaki plant in Waterville.

Maine warns against eating more than three fish a year landed from the Messalonskee. One fish landed from the stream tested at 68,810 parts per trillion for PFOS, or perfluorooctane sulfonic acid. The EPA hasn’t capped PFOS levels in fish but considers drinking water in excess of 4 parts per trillion to be hazardous.

Even trace amounts of some PFAS can be dangerous to humans, with exposure to high levels of certain PFAS linked to decreased fertility and increased high blood pressure in pregnant women, developmental delays in children and low birth weight, increased risk of some cancers and weakened immune systems.

PFOS is the most common forever chemical found in Maine freshwater fish — or at least among those 40 different human-made chemicals that make up the class of thousands, with more being added almost every day. It is what Maine uses as a chemical marker to set consumption thresholds for fish, milk and meat.

Fish sampling results topping 3,500 ppt of PFOS lead to state consumption advisories. The state warns against eating any fish landed from a water body once the average fish pulled out of the water body tops 60,000 ppt. Only five other places in Maine have PFAS consumption limits as low as the Messalonskee.

Quarry Road Trails didn’t pollute the Messalonskee Stream from which it draws its snowmaking water. It shouldn’t be up to a municipal ski facility that happens to be downstream, or a ski industry that relies on snowmaking to survive, to clean up someone else’s mess, a facility manager said.

Carlson agrees. When comparing the pre- and post-ban test results, the amount of PFAS left behind by snowmaking with a tainted water source isn’t as high as the amount left behind by fluoro waxed skis, Carlson said. Given climate change, Maine’s local ski areas have no choice but to make snow to survive.

But still, Carlson believes it’s a serious issue to be carefully considered, with filtration options explored.

“Everybody making snow faces the same problem,” Carlson said. “It’s not specific to QRT (Quarry Road Trails). It’s just that QRT has an idea what’s in its source water. But PFAS are likely to be in many sources of snowmaking water all over the world.”