Beavers react to Hallam Lake dredging project: Dam it!

When the team at Aspen Center for Environmental Studies started a project last fall to restore Hallam Lake to past glory, they weren’t 100% certain how wildlife would react.

The lake was drained to a low level so that hundreds of cubic yards of Chara algae, goose poop and sediment could be dredged by heavy equipment. Now that the first phase of the project is coming to a close, it appears the work had limited impact on the wild side.

“You would think there would be no wildlife here, that they would just disappear during the construction project, but the beavers have relocated (within the property), the bear is under our deck, the deer come through every day,” said Chris Lane, ACES’ CEO. “The wildlife is still coming through. There’s still ducks in the upper pond every night. It’s just interesting to see that wildlife didn’t totally vacate.”

The beaver had the most interesting reaction to the project. A beaver lodge on the lake has been occupied for as long as anyone remembers. When the water was drained, they relocated to a different part of the property and strategically created habitat to suit them, according to Adam McCurdy, ACES’ forest and climate director.

The beaver dammed a channel running along the berm that creates the lake. The water was diverted to an old channel that traditionally has held a smaller level of water. As the water level rose, they collected “a ridiculously large food cache” and apparently took advantage of large tree roots in the channel bank to create a new lodge. (For a more detailed description of the beavers’ work, see a blog written by ACES naturalist program director Jim Kravitz at AspenNature.org.)

McCurdy said the series of steps the beaver took to create a new home was interesting for the staff to observe.

“I don’t know that planning is necessarily the right word, but their kind of intuitive understanding of water and where they need to build dams to get water from one place or another or prevent it from going, it’s just fascinating,” he said.

The first phase of the rewilding project is coming to an end. The heavy equipment will depart the sanctuary by the end of February.

At the eastern end of the lake, a longer stream has been created with riffles and pools to expand trout spawning habitat. Small gravel lining the stream bottom will create spaces where eggs won’t get crushed or swept away in the current.

Soil pulled from that end of the project will be used as the foundation for expanded wetlands lining the stream.

“Most of our species depend on wetlands at some point in their life cycle, and it makes up a small fraction of our land, so increasing wetlands is a good thing,” McCurdy said.

Once the full water flow is restored, the stream banks might have to be tweaked by hand, and the wetlands will be planted with seedlings, seeds and willow cuttings. Some 11,000 seedlings are being grown in Idaho greenhouses for replanting later this year at the Aspen preserve.

“This is going to be a work in progress for the next two to three years,” McCurdy said.

Beyond the stream and wetlands, water will fill the now-deeper lake to bolster the habitat that makes the spot so popular with waterfowl and vast array of wildlife. Some of the sandy material pulled from the lake bottom was used to expand and strengthen the berm. Coves were created on the lakeshore to create additional places for waterfowl and fish.

The goal of the project is to create habitat that will last for generations. Hallam Lake was manmade during Aspen’s silver boom, and it served a multitude of functions. A smaller dredging and restoration project was undertaken in the 1980s after the site was dedicated as a nature preserve.

“And here we are doing it, again,” McCurdy said. “We don’t want to do it in our lifetimes, again. The goal is to really do it right and make it last. This is the last time people are going to see big yellow machines in Hallam Lake.”

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