Fire’s Role in Watershed Health


Wildfire in an overcrowded forest. Photo by Todd Heitkamp.

Being evacuated due to wildfires was a rather regular part of my childhood in the Colorado Rockies. The sight of the sun burning scarlet in a hazy sky and the thick smell of the smoky air are all too familiar. From the Buffalo Creek Fire (1996) to the Hayman Fire (2002) to the Lower North Fork Fire (2012) and more, my family and community have weathered many fires, some better than others. From my own experiences, I can empathize with the people who have had to evacuate for the Beaver Creek, Cold Springs, and Hayden Pass Fires that are all burning in Colorado right now. 

It wasn’t until I took ecology courses in college that I began to think about how different types of fires mean very different things for ecosystem health. The fact that wildfires have dramatic effects on watershed health may initially seem counterintuitive; it’s not immediately obvious how this relationship works unless you think of it in the context of wider ecosystems.

Lodgepole Pine Seedlings

Lodgepole pine seedlings and cone. Image courtesy of Yellowstone Digital Slide Files archives.

Fire is a natural and important part of ecosystem health. Beneficial fires are usually low-intensity surface fires, which stay close to the ground. They help remove dead vegetation and are a key component in the reproductive cycles of some trees. For example, lodgepole pines have evolved alongside fire and produce serotinous cones, which means they open to release their seeds in response to heat from fires. Thus, low-intensity ground fires help in the regeneration of forests, clearing out the dead and spurring the growth of new vegetation.

However, over a century of fire suppression practices and the subsequent pine beetle epidemic in the West have lead to a buildup of dead trees and other vegetation, which is perfect low-moisture fuel for more severe fires. Due to the lack of gradual fuel clearing by low-intensity fires, fuel density and the amount of ladder fuel in forests has increased. These are the right conditions for crown fires to wreak havoc.

Crown fires, as the name suggests, are high-intensity fires that burn into the upper canopy of forests. They are high-intensity and can spread much faster than ground fires, especially if the wind picks up. These are the fires that we tend to be more familiar with, since they have been increasingly frequent in Colorado and the West in recent decades.

When crown fires sweep through an area, they can destroy the hugely complex root systems of forests. These roots serve the ecological function of filtering water and slowing erosion. Without this filtration net, it becomes much easier for soils to wash away, doubly increasing the risk of water pollution, mudslides, and floods for those who are downstream. This includes wildlife, as polluted waters take a particularly heavy toll on aquatic species. According to Aaron Kimple of the Mountain Studies Institute and San Juan Headwaters Forest Health Partnership, the recovery of fish populations following a major fire depends on how much runoff is loading the river and what kind of refuge areas the fish have. Some fish have tributaries where they can maintain populations while runoff occurs and then more rapidly repopulate afterwards. Fish populations without refuges to escape heavy runoff can experience major die-offs, which have severe repercussions for local ecosystems and fishing economies.

These ripple effects often spread as far as urban centers, having major effects on cities’ water supplies. The ash, silt, and debris that washes into waterways due to increased erosion from wildfires increases the costs and slows the process of water treatment far into the future. It also becomes costly to repair and update water infrastructure, as Denver Water experienced in the wake of the Hayman Fire. The water provider had to spend “more than $26 million on fire-related restoration, maintenance, and dredging,” according to this article from National Geographic. Part of this fire mitigation initiative involved a partnership with the U.S. Forest Service on the Forests to Faucets project. This project “uses GIS to model and map the continental United States land areas most important to surface drinking water, the role forests play in protecting these areas, and the extent to which these forests are threatened by development, insects and disease, and wildland fire.” This information can then be incorporated into forest and watershed management plans across the state, in order to better allocate resources to the highest-impact areas.

Other Colorado communities are fostering similar partnerships and working together to manage their forests better and protect their water resources, as in the case of Pagosa Springs when they formed the San Juan Headwaters Forest Health Partnership. This group includes a variety of stakeholders that work together to manage forest health. “It’s important for communities to bridge traditional management boundaries for the overall health of the community and those downstream,” Kimple emphasized. Some of the partnership’s main forest management strategies include setting prescribed fires and thinning forests. These strategies used in tandem significantly reduce the risk of large, high-intensity fires. You can learn more about this community initiative from the video below by Christi Bode.

Fresh surface drinking water isn’t something that just comes out of our taps at home. It is a crucial common thread that weaves together all landscapes, from alpine forests to cities. Severe wildfires can be a significant threat to the quality of this precious ecosystem service, even when the destruction seems to be happening far away from major urban centers. Thus, it is crucial to reduce the risk of high-intensity crown fires before they happen, for the sake of entire ecosystems and our collective human well-being. Plenty more work still needs to be done in order to shift ecosystems closer to healthy fire regimes and the above-mentioned strategies implemented by committed, resilient Colorado communities are moving our landscapes closer to that goal.

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