Aspen’s Hallam Lake nature preserve has a new breed of temporary occupants

Heavy equipment dredging drained lake, rebuilding dam

Ducks surround the remaining water in Hallam Lake as it’s dredged at ACES in Aspen on Tuesday, Sept. 28, 2021. (Kelsey Brunner/The Aspen Times)

Instead of beaver, raccoons and raptors, visitors to Hallam Lake nature preserve in Aspen will spot front-end loaders, excavators and dump trucks over the next two and a half months.

But don’t fret, said Chris Lane, executive director of Aspen Center for Environmental Studies, Aspen’s sacred spot is being subjected to short-term pain for long-term gain.

“The idea here is to have this lake be a lake for the next 50 to 100 years so we can (maintain) all the biodiversity we talk about in education and wildlife benefit,” Lane said this week.

The lake has been drained and soon portions will be dredged of about 2,500 cubic yards of Chara algae, goose droppings and sediment that has accumulated since the last project of this type in the mid-1980s.

The dredging will increase the lake depth and improve aquatic habitat diversity, said Adam McCurdy, ACES’s forest and climate director. Some of the material scraped off the lake bottom will be used to fortify a dam built in the 1890s to bolster the wetlands area.

“Our engineer said weeks ago that with a shovel, in three weeks you could burst this,” Lane said of the dam. “It was coming undone partly because of dead and dying trees. The roots were rotting.”

The dredging project in 1987 or 1988 didn’t include bolstering the dam, McCurdy said. It has reached a point where it is essentially useless.

“The only thing that was keeping the lake there was the beavers,” he said.

The Hallam Lake Habitat Improvement Project will repair the dam, remove sediment to improve habitat for brown and brook trout as well as other aquatic life, expand and restore wetlands, and reroute a short stream between lakes for trout spawning. The cost is “hundreds of thousands of dollars,” Lane said. ACES’s fundraising for its 50th anniversary included the lake project.

McCurdy said the Chara was so thick in places of the lake that it went from the bottom to the surface and interfered with wildlife habitat. The macro-algae are already drying out now that the water has been drained.

The algae will return, which is beneficial because it provides habitat for macro-invertebrates that the fish feed on. The Chara will return, but it shouldn’t create a problem where the lake was dredged. In other places, mechanical means will be used to prevent the spread of the algae.

The lake is fed by numerous springs, so even though the lake’s water level was drawn down, many shallow pools exist. The smaller fish in the resident population of brown and brook trout are surviving in the pools. Some larger fish were transferred to the upper ponds but some fish are dead and dying because of the work. Blackbirds and magpies were feasting in the area Tuesday. Raccoon tracks also were spotted on the muddy lake bottom, McCurdy said.

The lake covers roughly 5 of the 25 acres at the ACES nature preserve. The site was a cultural center in Aspen’s silver mining era, and it has been ACES’ headquarters for 50 years. Thousands of school kids and countless other visitors stop by the area every year. Access must be restricted during the earth-moving project.

In the long run, the ACES staff expects the nature preserve to be more viable then ever as wildlife habitat. The dredged material won’t be hauled out until the ground is frozen. A carpet of thick wood chips has been laid down for the heavy equipment to use to access the lake. That will minimize soil compaction and allow vegetation to bounce back quicker, McCurdy said.

In addition, more than 10,000 plants adapted to the Rocky Mountain climate will be planted next spring to reinvigorate the numerous acres of wetlands on the property.

By next spring, public access will be restored to Hallam Lake. The nature preserve will again be thriving and kids will again be learning. Full recovery of the lake and surrounding lands will take awhile.

“We want Hallam Lake to be functional and recognizable to people as fast as possible so we’re putting a lot of effort into it,” McCurdy said. “It’s not going to be perfect right off the bat. This is going to take a couple of years for everything to come in.”


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