Return Of The Dammed After Generations Of Trying To Eliminate Beavers, Some Farmers Are Now Encouraging The Busy Rodents To Repair Parched Pastures

Lew Pence was called crazy by Idaho ranchers who thought the only way to restore eroded Western rangeland was to build tiers of $2,000 concrete dams.

But ever since a pair of beavers Pence relocated to a cattle-trampled stretch of Copper Creek did the job naturally, his how-to slide show has been in great demand.

Today, converts throughout the Western United States are using beavers to restore land that has been overgrazed, overlogged or otherwise abused. Beaver committees have been organized all over the region.

Still, the buck-toothed rodent remains unpopular with a lot of people.

On the positive side, the paddle-tailed dam-builders have proved to be better than humans at Copper Creek and some 30 other areas. When beavers re-engineer a watershed, they create new wetlands and improve water quality. Fish, ducks and grasses return.

“It’s not like I deserve a lot of credit,” says Pence, who is project manager for Idaho’s Wood River Resource and Development Area. “The Indians have been telling us for a long time that we need to put beavers back into the system.”

When University of Wyoming researchers supplied logs to beavers living in dried-up creeks near Rock Springs, Wyo., in the 1970s and ‘80s, the animals built dams and restored the eroded watershed.

Since then, the Beaver Committee of the Wood River organization, a coalition of ranchers and government agencies that fosters economic development in rural southern Idaho, has placed about 30 pairs of beavers along the Copper and other small creeks that water the once-lush grasslands of the Wood River basin.

“We started to show pretty good results several years ago,” says Pence, whose traveling presentation makes the point with dramatic before-and-after photographs of Copper Creek.

His pictures tell the story of how beavers reverse the erosion process. In the fall, they build dams of sticks, logs and mud that create moats around their lodges, where the animals spend the winter and rear their young.

The dams protect the land by slowing fast-moving storm water and spreading it across the ground to be soaked up by dry soil. Studies show that the dams also catch 90 percent of the eroded topsoil that otherwise would be washed downstream.

In Copper Creek, it took about four years for the level of the severely eroded stream to rise enough for grasses to return. Waterfowl, fish and the tiny organisms that live in healthy streams returned soon thereafter.

“Beavers give more to the system than they take out,” says Pence. “They get the water in there and that’s all it takes.”

Ecologists have dubbed North America’s largest rodent a “keystone species.” A Cherokee Indian legend says that God called on the beaver to help finish the Earth.

Archaeologists credit the animal with creating North America’s fertile prairies. Evidence of beaver dams dates back 55 million years.

Some scientists date the beginning of the decline of the continent’s great wildlife era to the killing of beavers for fur. Rampant beaver-trapping, which started with the opening of the Canadian West in the 1600s, all but eradicated the species from North America by the 1900s.

“Once we took them out of our system, the system went to hell,” Pence tells National Geographic. “Then we sat back and wondered what happened.”

He praises the return of beavers. Often, a pair will build dozens of dams, restoring parched meadows in as little as two years.

They can gnaw down trees in minutes and build a new dam in days - a helpful attribute when heavy rains change the course of a waterway overnight. “Concrete dams stay put,” says Pence, “But the beaver just moves with the creek.”

With few natural predators, such as otters and wolves, to pare their numbers, beavers are proliferating rapidly over much of North America, especially in wet coastal areas.

Not everyone is happy about that. The 40-to 60-pound rodent has a well-earned reputation as a pest in some places.

Denver has lost dozens of trees to beavers along its urban river parks.

Operators of golf courses with creeks running through them spend thousands of dollars each year trying to prevent the animals from reorganizing the fairways.

Animal-control officers in Fairfax County, Va., rate beavers as equal to deer as the No. 1 source of complaints.

Some ranchers are convinced that the animal they know as a varmint is more trouble than it’s worth. Some believe that beavers create unwanted wetlands and take food from their cattle.

“When you have beavers, you have to manage for beavers as well as cattle,” says John Shelly, a range conservation officer for the U.S. Forest Service in Idaho.

To assure beavers a source of building materials, he says, ranchers must prevent cattle from eating aspen, willow and cottonwood seedlings that grow near creeks.

But a growing number of ranchers now see beavers as a means to restore their lands and get environmentalists off their backs, Pence says.

“Ironic, isn’t it,” he asks, “that the little animals that opened the West might save it?”