If you had never heard them talk about one another, you might assume Mary O'Brien and Bill Hopkin were enemies.

Hopkin, a sturdy 68-year-old with a shock of white hair, grew up stringing fence and tending cows in conservative, pro-ranching northern Utah. Now the grazing management specialist for the Utah Department of Agriculture and Food, he says he's still "at my best when I'm talking over the hood of a pickup." Cattle, he fervently believes, can help rangelands thrive.

O'Brien, also 68, is elfish and unflinchingly direct, with a big laugh. She grew up in Los Angeles, devouring Willa Cather's books and falling so in love with grasslands that she would later encourage ecology students to honor native plants by thinking of each as a person. Before joining the Grand Canyon Trust, she earned an anti-grazing reputation for arguing against introducing cows to areas formerly grazed by sheep in Hells Canyon, on the Idaho-Oregon border.

Last May, at Kanab's Amazing Earthfest, O'Brien's husband mentioned that they had been married for 45 years. "I am so sorry," Hopkin cut in. But instead of spite, his tone revealed affection and respect developed working with O'Brien to improve public-lands grazing in Utah. Though federal managers say reforms in the '60s and '70s helped heal lands damaged by settlement's grazing free-for-all, conditions on southern Utah's three national forests, the Dixie, Fishlake and Manti-La Sal, have since largely plateaued. Ninety-seven percent of their land is grazed, and roughly on the same schedule, regardless of various ecosystems' needs. As a result, biodiversity and water quality have suffered, and environmentalist lawsuits and appeals have piled up.

O'Brien and Hopkin were in Kanab to showcase a different approach: A collaboration as unlikely as Earthfest's own celebration of public lands, where yogis rub shoulders with motorheads in a county best known for opposing public-land protection.

In 2012, Hopkin, O'Brien and a dozen other diverse stakeholders hammered out recommendations to make grazing on southern Utah's national forests more ecologically sustainable, while still economically viable. That they reached consensus is surprising, given environmentalists' historic opposition to public-lands ranching and ranchers' reluctance to embrace restrictions on an already difficult business. That it happened in Utah – where O'Brien's name is practically an epithet among many ranchers – is remarkable.

But it also happened because of that dynamic. Managers and moderate environmentalists say they must build social capital to get beyond stalemate to meaningful reform, especially as the Dixie, Fishlake and Manti-La Sal move this summer to overhaul their grazing policies.

"If I want a durable solution, I need as many people to own a piece of it as possible," says Fishlake National Forest Supervisor Allen Rowley, who will lead that effort. Adds Harv Forsgren, who championed grazing reform as the regional forester overseeing Utah, Nevada and parts of Wyoming, Idaho and California: "I think it's a turning point."

Reforming grazing policy has always been tricky in the West, given ranching's outsized political and cultural clout. Livestock nosh grass on about 80 percent of Bureau of Land Management holdings, and 60 percent of national forests. For nearly two decades, the Grand Canyon Trust's now-Executive Director Bill Hedden has tried to ease that pressure on the Colorado Plateau, including by working directly with willing Utah ranchers and officials to retire grazing leases and remove cows from federal land. But that did nothing for still-grazed land, and agency support for retirements in Utah eroded during George W. Bush's tenure, Hedden says. "The basic public-lands grazing work there backed way off."

Hoping to spur broader change, O'Brien, an ecologist, began collecting data on damage the Trust and others wanted to repair. What volunteers found across the three southern Utah forests was disturbing: Livestock and wild ungulates appeared to be chewing aspen stands to death. Big trees persisted, but shoots weren't surviving to become saplings. The same was true of cottonwoods and willows. Armed with this, O'Brien helped stir up a collaborative group in 2009 that produced aspen restoration guidelines that included modifying grazing. It was on that project that she and Hopkin bonded over their concern for Utah's landscape. "When I saw some of the aspen, I was devastated," Hopkin says.

Forsgren and Rowley saw an opportunity in the aspen group and others. "There was a nucleus of players we might be able to build something with," Forsgren says, including state officials who agreed the status quo was unsustainable.