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Balancing out the beavers

Local groups work to find compromise between Dredge Lakes wildlife, trails and area natural resources

Posted: June 16, 2011 - 5:00pm
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Tom Hanna, right, Jarvis Schultz, center, and Bob Shaw move a culvert pipe into place at Norton Lake in the Dredge Lakes area on Wednesday, June 8. The lake has been dammed by beavers and the culvert, also called a leveler, will help control the water level to reduce flooding on nearby trails. It is one of three now installed in the Dredge Lakes area.   Michael Penn / Juneau Empire
Michael Penn / Juneau Empire
Tom Hanna, right, Jarvis Schultz, center, and Bob Shaw move a culvert pipe into place at Norton Lake in the Dredge Lakes area on Wednesday, June 8. The lake has been dammed by beavers and the culvert, also called a leveler, will help control the water level to reduce flooding on nearby trails. It is one of three now installed in the Dredge Lakes area.

The perimeter of the pond smelled like low tide and earth. Mud, the color of dried seaweed and terra cotta, had begun to crack as moisture evaporated. It was clear water had ruled these banks only a day or two before.

Here, on the outskirts of Norton Lake, one of the many trails of the Dredge Lakes Trail system disappeared beneath a swath of knee-deep standing water. The trail was still impassable, despite the lowered water level.

An adjacent beaver dam proved to be the culprit of the flooding. But instead of the silence that comes with sitting lakeside, water could be heard running just beyond the stands of alder and horsetail.

“Flowing water just drives the beavers nuts,” Mary Willson said.

She led the way along the top of the dam, a raised pathway of mounded mud and sticks, until we reached the source of the running water.

Buried deep into the base of the dam was a black plastic culvert. Water flowed out the downstream end in a steady gush, blocked only by a wide, wire mesh screen. On the other side of the dam, the black of the culvert could be seen stretching deep into the lake. A large wire mesh cage marked its end.

Willson, who is a retired professor of ecology and co-leader of the Beaver Patrol, had been one of eight who worked last week to install the culvert. The group, who has worked since 2007 to preserve the resources, trails and animal residents of the Dredge Lakes area, spent a full day installing two of these apparatuses. Willson said they are called levelers and their installation will help lower and manage water levels in flooded areas and restore currently un-useable trails.

“It’s down over a foot from what it was,” Willson said.

She gestured toward the middle of the lake. Water lines on snags and horsetail showed a clear 12 inches of freshly exposed material. Willson then pointed to a mound of sticks on the bank. It looked like an abandoned woodpile.

“There’s the lodge. That one is pretty good size,” she said. “All the garbage out front is their winter cache.”

Similar “garbage” surrounded the culvert, as well as fresh black mud, weeds and grass.

“The beavers have added all this stuff on top,” Willson said. “In the last several nights they’ve added a lot of mud and all these sticks.”

Water continued to flow, despite the beavers’ efforts to dam the culvert further.

The goal, however, is not to drain the lake completely, Willson said. Doing so would expose entrances to the beavers’ lodge, which would make them prime targets for predators. Hence, the levelers are constructed to be adjustable. The downstream ends can be moved up or down as needed to maintain the ideal water levels.

Because besides maintaining the trails, the group also wants to create sustainable habitat for the beaver and for the anadromous fish runs that arrive each fall in Dredge Creek.

Both the Beaver Patrol and the Alaska Department of Fish and Game want to preserve what exists of the fishery in the Dredge Lakes area, Willson said. The ADF&G has made efforts in the past to stock area lakes, such as Crystal, but she said it’s hard for a natural population to take hold because many of the lakes are quite isolated and, in times of low rainfall, the fish have no way of accessing the water bodies of the Dredge Lakes area.

Since 2007, the beaver have been busy occupants of the area, Willson said. They arrived much earlier, probably around 1950, but their presence didn’t start raising eyebrows until the trails, which are frequented by dog-walkers, hikers and runners, became flooded as a result of the animal’s dam-building abilities.

She said the Beaver Patrol formed after the U.S. Forest Service talked of resolving the issue by trapping the beavers.

“We wanted to find a more civilized compromise,” Willson said.

Ed Grossman, recreation program manager on the Juneau Ranger District, said the group essentially took over the heavy task of beaver activity management. Since the land is owned by the Forest Service, the burden was originally on their shoulders.

“(The Beaver Patrol) learned a lot, including how much work it really is,” he said. “They have come to us over the last few years to talk about different ideas for the fish, the folks maintaining it and keeping the trails dry. It’s been a good partnership.”

But now, after three years of weekly manual labor, Willson said the volunteer-driven group sought a different solution.

They contacted Mike Callahan, a beaver control expert who had worked to control the animal’s activity in Massachusetts.

“He built these (levelers),” Willson said. “It was his job, his business to take care of beaver problems for people. We all chipped in for the plane fare and brought him out to look at the area.”

Willson said Callahan’s advice was valuable and the group installed a leveler in Crystal Lake last year to test its functionality. So far, that installation is working as planned.

“We had to adjust it two or three times, and now we just check it periodically,” she said. “It’s doing what it should and it’s exactly the same system (as those recently installed).”

But to continue installing levelers, the Beaver Patrol needed funding.

Pat O’Brien, co-leader of the Beaver Patrol, said they sought a grant through Holland America in August of 2010 for $1,900 — just enough to pay for materials.

The group won the grant, acquired materials and with the help of the Forest Service, stored the pieces until last week.

“We hauled the materials out for the group,” Grossman said, “then hauled out the remainder.”

For the eight volunteers doing the installation work, it was a muddy day filled with manual labor. Nearly all are retired and O’Brien said volunteers are driven to help because they see how valuable the creatures are to the ecosystem.

“We really have rich bird life largely because of the beavers,” O’Brien said.

Beavers also incidentally create habitat for aquatic insects, which in turn provide food for toads, fish and birds, to name a few. They also provide a rich habitat for coho salmon fry, which in turn support a wide diversity of critters that feed on them such as herons, dippers, mink, otters and Dolly Varden. From there, the list goes on, as the varieties of species that benefit from the presence of beavers lengthens.

For members of the Beaver Patrol, the levelers will help reduce work for the group. This, Willson said, is a welcome benefit.

“(We’ve been) coming out once a week, when there’s lots of water it means twice a week, to clear out culverts, keep it open for fish passage. It’s a sizable time commitment,” Willson said. “(The installation of these levelers) reduces the labor fantastically in the long run.”

She said the group will now turn to the Forest Service for help. Wilson said they’d like to see trails raised, or even re-routed, to allow passage in flooded areas, like those near Norton Lake, that are likely to remain submerged.

Grossman said that will likely happen, but the Forest Service first wants to see how successful the new levelers are.

“We’re going to watch to see if (they) work,” he said. “Raising the level of the trail, that is an attractive option because of the readily available fill in the ‘pit.’ But, we want to see how these things work, first.”

Still, he said the lowered water levels already offer benefits for winter users.

“Lower lake levels means less risk to skiers who may fall through,” he said. “Over the long term, we’re learning that a slight re-route might benefit beavers and users. But, (we’re hoping) the levelers will work well enough that we won’t have to do that.”

Overall, he said the Forest Service is grateful to have the help of the Beaver Patrol.

“We’re happy to have them out there. We’ve mutually benefitted and mutually learned,” Grossman said. “The area they’re tackling now is the last real problem zone. It’s been a good partnership that has given more options for the beavers. We look forward to keeping all the goals in place.”

Willson said the plan now for her group is to just keep watching the newly-installed levelers and to keep existing culverts and trails clear.

As she stood on the beaver dam, surveying the work the beavers had done since the installation of the new leveler, she went silent. She peered through the water. There, on the top of the culvert were chew marks.

“It certainly looks like somebody’s been chewing on it,” she said. “They’d have to take out that whole outer layer to get to the inner wall.”

Willson turned back toward the trailhead.

“That should be fun to watch,” she said.

 

• Contact Outdoors Editor Abby Lowell at abby.lowell@juneauempire.com.

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