Updated

Astride sturdy mustangs named "Okanogan" and "Spurs," U.S. Border Patrol agents Darrel Williams and Justin Hefker ride quietly along a ridgeline above the Similkameen River valley.

The mustangs are among a dozen the Border Patrol's Spokane Sector has bought to patrol a 308-mile (495-kilometer) -long section of the U.S.-Canadian border from the crest of the Cascade Range in Washington state to the Continental Divide in Montana.

"The reason we went with the horses was to get into those hard-to-reach areas," said the patrol's assistant chief of the region, Agent Lee Pinkerton. "We can really reach out to some of these remote locations."

The Border Patrol, a division of the Department of Homeland Security's Customs and Border Protection, routinely uses horses on the southern border with Mexico. But the mustangs owned by the patrol's Spokane Sector are the first to watch the northern border, said Pinkerton.

The Border Patrol's "Operation Noble Mustang" adopts horses from the U.S. Bureau of Land Management's wild horse and burro program, blending today's technology with yesterday's law enforcement traditions, the agency said.

On a recent day, Richard Graham, agent-in-charge of the Border Patrol station in Oroville, rides along as his agents patrol a small section of the border. The avid horseman sings the praises of mustangs and their ability to patrol the border with minimal environmental damage.

In the valley below, aspen, cottonwoods and a few pine flank the river that flows into the U.S. from Canada. Along the river is a Prohibition-era dirt "whisky trail" that shows recent activity from modern smugglers bringing different contraband, most likely potent "B.C. Bud" marijuana, from Canada.

The breed's big bones and large hoofs give them a sure-footedness that makes them a perfect fit for scaling the steep hillsides and thick forests along the border, Graham said. They also have less of an impact on the fragile wilderness ground than motorized vehicles, he said.

"These horses are truly American. They are a product that's unique to the United States and we are putting them in a position to help us protect the U.S.," Pinkerton said. "There's something inherently right in doing that."

The patrol contracts with local ranchers to board and feed the animals. Because they are owned by the government, the agency saves money it used to have to spend to lease horses from local ranchers, Pinkerton said.

The mustangs were rounded up in the BLM wild horse adoption program, broken by inmate wranglers at a Colorado prison, then sent to the Border Patrol's Colville station in Washington state for final training.

Graham's station is responsible for an 80-mile (130-kilometer) stretch of border that includes about 50 miles (80 kilometers) of the vast Pasayten Wilderness Area, a 529,477-acre (214,276-hectare) tract where motorized vehicles are prohibited and there are few, if any, roads.

Along the Spokane sector, agents also patrol the smaller Salmo-Priest wilderness of northeastern Washington state, as well as Montana's Glacier National Park, where it abuts Canada's Waterton Lakes National Park.

Law enforcement aircraft have limited use in the wild, Pinkerton said. It is difficult to see people hiding beneath the tree canopy and wilderness laws limit how low aircraft can fly, he said.

"We're going back to the 1800s style of doing this because it is successful," he said. "On the ground, a horse is going to be the best mode of transportation in those areas."

Agents on horseback look for signs of border crossings and watch for low-flying aircraft that drug smugglers are increasingly using to bring potent "B.C. Bud" marijuana south.

A drawback is heavy snow that keeps horses out of some high country areas for months at a time during winter, and spring runoff, which makes some creeks and streams impassable, Pinkerton said. But those natural hazards also keep smugglers out of those areas, he said.

The need for the mustangs became more urgent after Sept. 11, 2001, Graham said. Previously, the Border Patrol's focus in the area was rounding up illegal workers in orchards and fruit packing houses in north-central Washington state. Now, the threat of terrorists sneaking into the country is a bigger concern.