Dam-clearing efforts prove effective

Volunteers help clean culverts as alternative to beaver-culling plan

Posted: Sunday, December 28, 2008

Perhaps the Dredge Lake area beavers were displeased to note the humans that arrived each day this summer to unplug the culverts and tear down the dams they had so carefully blocked and built up. But those beavers are lucky to be alive.

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Brian Wallace / Juneau Empire
Brian Wallace / Juneau Empire

The U.S. Forest Service held off on a plan to let trappers cull the beavers, and allowed volunteers this summer to undo the beavers' work.

So far, so good, admits the agency. The culverts in Steep Creek, Dredge Lake and the nearby holding pond are clear, meaning the nearby trails are in less danger of flooding and the dams are open enough that fish can pass through.

"I learned a lot from this effort - not about beavers, but about how to work with people and the public," Juneau District Ranger Pete Griffin said in a statement. "To manage resources we need to ask the right questions, and in asking sometimes the public comes up with a possible solution that we hadn't considered."

The solution was hauling sticks.

"I'm the only certified 70-year-old culvert crawler in the world," joked Mary Willson.

She and Bob Armstrong, both retired biologists in their 70s, came to the Forest Service with the alternative to beaver-culling in late 2007.

Armstrong and Willson guess - nobody has studied the beavers much - that the beaver population is about 15 active beaver families, perhaps at its peak now. They eat cottonwoods, willow and alder bark.

They are as industrious as stereotyped. They're vulnerable on land, but near-invincible in the water, so they build dams and canals that keep water deep enough for them to work and play in.

"You'd be amazed at what beavers can put in," Armstrong said. "Sometimes they'll put in a tree that takes two people to lift."

Beaver dams blocked culverts. Fish couldn't get through and trails flooded.

But beavers' structures also help other species. Armstrong, a retired fisheries biologist, said studies show young fish grow faster and more abundantly behind beaver dams. In other parts of the Pacific Northwest, managers are considering stocking beavers to help fish populations.

Armstrong and Willson believe that removing the beavers from the area would ultimately harm the coho, sockeye and Dolly Vardens in the area - and all the birds and creatures that rely on them.

So they frustrated the beavers' efforts, instead.

The effort started with clearing the six-foot-wide Steep Creek culverts.

"It took many people several days, because they were stuffed absolutely full," Willson said. "When we took the last bits out, the fish went right underneath us."

From there, a core group of five people - Jenny Pursell, Pat O'Brien and Lorraine Murray - rotated beaver duty each week. Other volunteers came in, including kids with Juneau Youth Services. At one point, Willson hired three high school football players.

There were some hitches. For one, the work was harder than it would be if the culverts were all in good shape. Two of them are faulty, Willson said.

Also, the Forest Service had put in beaver bafflers, which are fences around the culverts to keep the beavers out and fish going through. But somebody cut them, perhaps by someone who felt the fish couldn't get through, and the beavers had no problem swimming through and building around them.

Meanwhile, children with Discovery Southeast and the Forest Service day camp came to learn about the beavers. That's part of these creatures' value, say the volunteers.

Armstrong and Willson, too, learned about the creatures they were helping all summer long. They watched them groom, touch noses and play with each other.

"I've had a tremendous amount of fun watching them," Armstrong said.

As a result they're publishing a book on the local beavers, which they intend to sell at the Mendenhall Glacier Visitors' Center this spring.

For now, the beavers have ceased plugging culverts with such alacrity. They have hunkered down in their lodges for the winter, with piles of sticks nearby if they get hungry.

But next spring, they'll likely be back. And the question is how much longer the septuagenarians Willson and Armstrong will continue slithering into culverts to pick out the sticks.

"To really fix the problem, it will require money," Armstrong said.

Willson said that the Forest Service and Trail Mix Inc., Juneau's nonprofit trail-building organization, were drafting a plan to rebuild the trails higher and put in new culverts and beaver bafflers. That could lessen the need for beaver duty, and the pressure to kill them, Willson said.

"The beavers themselves are just doing what beavers do," Willson said. "They respond to flowing water in an innate way; it says to them, build a dam."

• Contact reporter Kate Goldenat kate.golden@juneauempire.com.

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