Eagle River Watershed Council: How fires impact our rivers
Fire is in the headlines these days, with more than 4 million acres burned to date this year on the West Coast. Our fire season here in Colorado has seen the two largest fires in state history with the Cameron Peak Fire on Wednesday surpassing the Pine Gulch Fire in acreage burned.
Locally, the White River National Forest saw its largest fire in history, with the Grizzly Creek fire that has burned more than 32,000 acres in and surrounding Glenwood Canyon. Thanks to the efforts of first responders, fire crews and management teams, I-70 has since reopened, Shoshone Powerplant has been spared and life has resumed to a somewhat normal buzz. Well, as normal as 2020 can be.
As a headwaters community, there’s a lot at stake when it comes to our local rivers — from a multi-billion-dollar impact on the economy to a river that provides water to 40 million people downstream throughout the West. So, how will a fire like Grizzly Creek impact our rivers and beyond?
Forest ecosystems and fires have a complicated relationship. Fire is a natural process and can provide benefits to watersheds, such as clearing dead materials, sprouting new growth and releasing nutrients into the soils. Some species rely on instances of fire for survival, such as lodgepole pine. But with today’s fires burning bigger and hotter than ever, they can pose a threat to the rivers flowing near those forests.
Fires burn inconsistently, leaving a wide range of burn types throughout each area, but it is those areas with severe burns that often prove most detrimental to watershed vitality. Bill Hoblitzell, a watershed scientist with Lotic Hydrological, shared that in those areas, “you can get a hydrophobic layer on top of the soil that actually repels water for a little while after the fire comes through. And, you’re also losing all your vegetation that holds soil in place over time.”
This combination can cause flash floods, debris flows and sedimentation in the rivers and smaller streams, especially when heavy precipitation events occur. They pose large risks to stream health and safety of the community, damaging infrastructure, choking out a stream and harming the aquatic species. These effects do not necessarily occur right after a fire, but can happen years into the future until ground cover can regrow.
Eventually, those areas of larger rivers, such as the Upper Colorado, that were affected by debris and fine ash will experience dilution of the debris, but Hoblitzell says that “it tends to be a bigger problem for small streams,” such as Grizzly and No Name Creeks.
In Glenwood Canyon, communities and human infrastructure are threatened by debris flow events, including drinking water intakes for the City of Glenwood Springs. Addressing these concerns can be challenging and costly.
Impacts of fire retardants
Fire retardants, which are often applied via aircraft, are a critical piece of fire fighting and help tremendously to slow and stop the movement of fire. Containing phosphates, sulfates, clay, thickening agents, water and trade-secret performance additives, retardants dilute the combustible gases of the fuels (wood, debris, etc.) and coat them to create a barrier that limits the release of flammable gases.
These chemicals linger in the environment after the fire, but break down with time. Timm Paxson, a retired chemist and past board member for the Watershed Council says that, “once broken down, these compounds are useful to the plants. Phosphates are essential to plant life.”
However, too many phosphates can cause algae blooms within a river system, depleting the oxygen and sunlight available to other species. Thus, fire retardants are not allowed to be dropped within 300 feet of a body of water, such as a river.
Beyond the fire
Eagle County faced fire recovery in 2018, with the Lake Christine fire in the hills above El Jebel and Basalt. Though much smaller and impacting a different landscape, we can use the post-fire response in that area as a test case for what steps to take with the Grizzly Creek burn area. The successes here were largely from collaboration with many stakeholders — something local groups, including the Watershed Council, are already working on in the Grizzly Creek area.
A source of hope that Hoblitzell points out is that “these natural systems are very resilient, they have been operating for millennia … and they do bounce back.”
After a year like 2020, perhaps that is a lesson we can learn from our local rivers and streams — resiliency and the ability to rebound.
James Dilzell is the education and outreach coordinator for Eagle River Watershed Council. He can be reached at firstname.lastname@example.org. The Watershed Council has a mission to advocate for the health and conservation of the Upper Colorado and Eagle River basins through research, education, and projects. Contact the Watershed Council at (970) 827-5406 or visit erwc.org.