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Beavers Work Hard For River Ecosystems

Jul 24, 2019


Development and climate change are top threats to wildlife habitat and biodiversity, and in the arid west, water supply is a consistent concern for all kinds of life. But ecologists see a simple, natural way for ecosystems to be more resilient: beavers. 

When local ecologist Delia Malone walks along the Crystal River in Carbondale, she sees something missing. This footpath runs through an area that used to flood during spring runoff, but with the combination of development and climate change, it doesn’t anymore. Malone said it’s also in part because there are no beavers on this stretch of river. 

"When we lose beaver, we also lose the wetlands they create, we lose the water storage,” Malone said. “Beaver dams store tremendous amounts of carbon. When beaver dams dry out because the beaver have left, that carbon goes up and is contributing to global warming."  

People have aggressively pushed beavers out of some areas, especially when they damage irrigation systems, flood fields or roads and cut down trees on people’s property. 

The rodents also create natural water storage, even in dry years and restore wetlands. Malone wants to bring more of them to high elevation public lands in the Roaring Fork Valley. She’s working with researchers at the Colorado Natural Heritage Program on a computer model that will indicate suitable habitat for beavers. 

Delia Malone walks along the Crystal River, in an area that she says could benefit from beaver activity.
Credit Elizabeth Stewart-Severy / Aspen Public Radio

"Beaver can be a simple but really important strategy to remediate the impacts that we've caused by changing our climate," Malone said.    

A 2018 survey by Colorado Wildlife Science found that when beavers return to suitable places, the health of the river ecosystem improves.  The willows grow faster, there’s more food for other wildlife and there are more songbirds. 

Hallam Lake, a 25-acre nature preserve tucked into a hillside behind the Aspen post office, is a haven for diverse forms of life. Water pools and drops gently through several ponds, which are fed year-round by natural springs. Hallam Lake is home to the Aspen Center for Environmental Studies (ACES), and this beauty is possible because of a family who’s been living here for decades. 

"Beavers are maintaining this lake," said ACES’ naturalist programs director Jim Kravitz. 

The lake is full of life. A recent study found 20 mammal species, dozens of insects, as well as more than 150 plant species, including a carnivorous plant called the Lesser Bladderwort, and 15 species of lichen. 

"This is sort of this unique ecosystem here, because of the spring water, because of the beavers," Kravitz said.  

Beavers have lived under the roots of spruce trees along the banks at Hallam Lake for decades, and they work hard for the local ecosystem. 

"They slow down the water, they filter out pollutants, they slow down floods, they keep the water on the land,” Kravitz said. “They have so many benefits, especially in dry places and where water is going to be a concern in the future."

With climate change driving persistent drought, that means beavers could help out the entire western United States.