Craning his neck to see over the small airplane's instrument panel, Ron Gardiner points out the path Spanish explorers had to take around the deep crevasse that cuts through the center of northern New Mexico.
To the west of the famous Rio Grande gorge and its towering basalt cliffs is a broad plateau of sagebrush, native grass and remnants of the ancient volcanoes that helped form this rugged landscape. Herds of elk, pronghorn antelope, bighorn sheep and golden eagles call it home.
"This is one of the last undeveloped tracts in the Southwest," said Gardiner, a water policy consultant who is among those who have been spearheading the decades-old effort to protect the area.
The push to set aside nearly 370 square miles as the El Rio Grande del Norte National Conservation Area is part of a new wave of congressional proposals aimed at protecting more than 34 million acres of public land across the West.
However, as conservationists continue with their crusade, some people who make a living off the land are digging in to oppose the effort.
Critics are concerned that domestic energy production and traditions like ranching and firewood and pinon nut gathering will be limited as more tracts of public land are designated as conservation areas or wilderness.
Conservationists say they are trying to keep momentum going following the enactment last spring of a massive public lands bill that added more than 2 million acres to the nation's inventory of wilderness and other protected lands.
Other legislation has been introduced to designate areas in Alaska, Idaho, Montana, Oregon, Washington, Wyoming and Utah as wilderness and wild and scenic rivers.
"I'm aware of campaigns in just about every western state to designate new wilderness areas," said Paul Spitler, associate director of The Wilderness Society's national wilderness campaigns.
The El Rio Grande del Norte legislation — which has the backing of the Obama administration — would permit grazing, hunting and fishing and the gathering of firewood and pinon nuts. But no new roads would be allowed, and the land management agencies that oversee the area would not be able to lease or sell any parcels.
The legislation also would set aside two parcels within the conservation area as wilderness — one encompassing the 10,093-foot Ute Mountain and the other along the Rio San Antonio.
Some cattle ranchers are concerned the proposal would limit access to public land where they have grazed cattle for years. In wilderness, vehicles are not allowed.
"Taking care of improvements, developing water, having access to be able to maintain fences and other things sometimes become very difficult," said Gerald Chacon, a Rio Arriba County rancher and member of the New Mexico Cattle Growers' Association board of directors.
"What it essentially does is it's just sort of a way of squeezing you out of business," he said.
But Gardiner, sportsmen and other supporters argue that Sen. Jeff Bingaman, D-N.M., worked hard to address the concerns of ranchers and local residents.
Greg McReynolds, a public lands coordinator for the nonprofit sportsmen group Trout Unlimited, doesn't consider the bill controversial.
"We're not trying to take anything away, we're not trying to change anything," he said. "We're just trying to protect it like it is."
The area is relatively untouched because of its rugged character, Gardiner said. The gorge and the lack of water on the plateau kept Spanish explorers and later pioneers from moving across the area.
"This has always been a land to circumvent," he said.
The area is an important winter range for elk, deer and antelope. It's also part of a migratory flyway and home to several pairs of eagles. One nest along the gorge north of the Taos bridge stands several feet tall and is about 20 years old.
The argument for protecting El Rio Grande del Norte is similar to the cases being made for the Wild Rogue River in southern Oregon and millions of acres in Utah's red rock country. Conservation groups are also pursuing protection proposals for both.
Bob Gallagher, president of the New Mexico Oil and Gas Association, said some areas deserve to be protected. Still, he believes conservationists are making an effort to "grab more land and keep it out of bounds."
"If you're in a western state and you're not concerned about that, then you haven't been following what's going on," he said.
El Rio Grande del Norte is east of the San Juan Basin, one of the largest natural gas fields in the nation, and south of several exploratory wells in Colorado.
However, supporters of the proposed legislation said the threat is more about development along the gorge than drilling.
"People love the canyon and there are opportunities to build right up to the rim," Gardiner said.
Supporters also say the designation could be a tourist boon for the nearby communities of Questa, Taos and Red River. In 2007, more than 300,000 people visited the Rio Grande gorge and 33,000 paid New Mexico rafting outfitters for guided trips along the river.
"There is an intrinsic value to renewable recreation resources and this is a prime example of how a landscape provides for a community and an economy and brings something really valuable to the state," McReynolds said.