That’s the whole thing, to get inside a barrel wave,” says Elijah Mack, surfer, barber, Portlander. “Everything else stops.” Interestingly, Mack’s talking about surfing rivers, not oceans. And he says that his collaboration with a Denver engineering firm has created barrel waves (or “the most perfect waves possible”) on rivers.

According to Mack, the river-surfing community has historically viewed the prospect of man-made barrel waves with skepticism—and with more than 200 river waves logged on his board, the “godfather of river surfing” would know. (The curious can find a video of Mack surfing the Deschutes River’s “Trestle” wave on the website of Riverbreak magazine.) But that changed when he met Benjamin Nielsen, a fellow river surfer who also works as an engineer at Denver’s McLaughlin Whitewater Design Group. That hydraulic engineering firm won renown within the sport by placing wave-shaping steel plates on a river bottom to create a coveted wave at Idaho’s Boise River Park.

Nielsen’s firm hired Mack to collaborate on a low-flow wave for Colorado’s South Platte River. Five days of research at Colorado State University led to a plan for reengineering the bottom and banks of the river. In a model, the changes produced what Nielsen describes as “a very specialized wave. The form of the barrel depends on the manipulation of slow downstream water and fast upstream water. The design is really about manipulating the wave elements in three dimensions, where some wave designs only work with two.” Mack and Nielsen come from different worlds—Mack runs a bustling barbershop, Nielsen is an alum of a rigorous engineering program at Cal Poly San Luis Obispo—but they bonded over their shared belief that river surfing’s future depends on more reliable waves. “If you don’t have waves, you don’t have surfers, and you don’t have a community,” says Nielsen.

The scale model’s new geometry for bank elevations and the river bottom will be applied once Nielsen’s company decides on a location. Mack is already excited. “This will change the face of river surfing,” he says.