Every winter, more than 10 million people hit the slopes in Colorado, almost all of them with skis and snowboards coated in petroleum-based wax for optimum schussing. That grease can often get left behind, a problem considering the manufactured compounds used in many such waxes don’t always decompose naturally. When the snow melts, perfluorochemicals (which studies suggest cause thyroid issues in animals and humans) and hydrocarbons (a less toxic substance, but one some scientists say may not be fully biodegradeable when used in large quantities) can eventually enter streams and rivers.

The thought of wax in his water inspired Peter Arlein to invent a greener alternative: In September, the Carbondale resident unveiled MountainFlow Eco-Wax, North America’s first line of plant-based ski waxes. A longtime ski bum, Arlein spent two years studying the science of friction and boiling various waxes in a shed in his backyard. He’d then take five pairs of skis, each finished with a different formula, to Aspen Snowmass and test their performances on the slopes. Arlein won’t disclose the winning recipe, but eventually he settled on a special stew of five plant oils that, he claims, can compete with petroleum waxes when it comes to limiting resistance and maintaining speed.

Maile Spung, owner of 40-year-old Aspen outfitter Ute Mountaineer, agrees, saying MountainFlow ($14 to $19) performs as well as less eco-friendly waxes made by industry giants, like Swix. In addition to Ute, about 100 other North American retailers, including more than 30 in Colorado, are selling MountainFlow—a signal that skiers may no longer be interested in mixing petroleum and water.