Hallam Lake – Back in Action!

ACES Staff

March 31, 2022

Hallam Lake – Back in Action!

In September 2021 ACES undertook a major repair and restoration project at Hallam Lake. After five months of work, all the heavy equipment has left the Lake, and the preserve is once again open to the public. As the lake refilled much of the wildlife has started to return. Over the next two years, ACES will be focused on continuing the restoration work by vegetating newly created wetlands and revegetating areas that were disturbed during the work.

September 27, 2021

January 4, 2022

What was accomplished

After months of work, we were able to accomplish many of the goals that we set at the start of the work. We’ve added almost one acre of emergent wetlands to the preserve. Wetlands only account for 2% of Colorado’s land area but 75% of species depend on them for some part of their life cycle. Much of the land around Hallam Lake is classified as wetlands but there aren’t many emergent wetlands. Emergent wetlands have soils that remain fully saturated throughout much of the year but aren’t underwater. In addition to improving terrestrial habitat, the restoration work also focused on aquatic habitat.

We improved aquatic habitat by significantly increasing the depth diversity in Hallam Lake and increasing the length of trout spawning channels. Before the restoration work, much of the lake was the same depth. Additional depth diversity promotes increased biodiversity of aquatic invertebrates and plants and provides additional habitat for fish. In the upper ponds, we doubled the length of the trout spawning habitat. Like most salmonids, trout swim upstream to reproduce. The increased availability of spawning habitat at Hallam Lake will help maintain healthy fish populations.

The final goal of the project was to reinforce and repair the earthen berm that creates Hallam Lake. In the late 1880s miners built Hallam Lake by constructing an earthen berm to back up the many natural springs in the area. While Hallam Lake isn’t natural it has become an important part of the ecosystem with many species depending on it. The work accomplished during this project will ensure Hallam Lake persists for years to come.


There’s no denying that restoration work at Hallam Lake had a significant impact on wildlife. While the lake was drained much of the wildlife that inhabits Hallam Lake left the area. Beavers that lived in Hallam Lake had to abandon their historic lodge, fortunately, they were able to establish a new lodge in some of the wetlands between Hallam Lake and the Roaring Fork River. Read more about the beavers’ new habitat here. Less than a week after Hallam Lake was filled we found beaver tracks going from those wetlands into Hallam Lake, later a wildlife camera captured a beaver beginning to explore the newly refilled Hallam Lake.

The restoration project decreased the fish population of Hallam Lake. We were able to move many of the fish to ponds that weren’t impacted, some of the fish moved into the wetland towards the Roaring Fork River, and others found areas of the lake that held water and weren’t impacted, and some died when the water level was dropped. Based on a similar project that was done in 1988 we’re confident that the fish population will fully recover in the next five years. Hallam Lake has always been an extremely productive fishery and with the added depth and increased spawning habitat, we expect this to improve.

Waterfowl and other birds that frequent the lake are once again being seen in the area. The Great Blue Herons which nested at Hallam Lake last year have been spotted again. Additionally, King Fishers, Bald Eagles, Ring Neck Ducks, Hooded Mergansers, Northern Pintails, Green-winged Teals, Mallards, and Cinnamon Teals have all been seen at Hallam Lake since the end of construction.

Great Blue Heron at Hallam Lake
Great Blue Heron at Hallam Lake
Mule Deer at Hallam Lake
Mule deer in Hallam Lake

What is left to do?

The heavy construction has ended but the restoration work is only just beginning. As the snow melts around Hallam Lake the new wetlands we constructed over the winter will begin to emerge. Right now these areas are barren soils, left alone they could erode or become home to invasive species. Over this summer we’ll be working with a team to plant these areas ensuring a robust and diverse community of plants establish these new wetlands. We’ll monitor fish populations and determine if any additional steps are needed to ensure their continued recovery. 

Change in nature is often very slow, there are trees in the Roaring Fork Valley that germinated before Europeans arrived in the Americas. But after a disturbance change happens rapidly, for example after a fire, an avalanche, or a flood. At these times change can happen at the scale of weeks or years rather than decades or centuries. While the restoration work at Hallam Lake isn’t natural, it is a once-in-a-lifetime chance to see an ecosystem change at a rapid pace. We encourage you to come see Hallam Lake over the next several years as the new wetlands and disturbed areas evolve from barren soil into a fully functional ecosystem.


Adam McCurdy

Forest & Climate Director

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