People have been musing about Northern Colorado’s “next High Park Fire” for eight years, since the devastating wildfire scorched 87,000 acres in the Poudre Canyon in June 2012.
Its successor arrived on Labor Day weekend, in an acreage sense, when heat and gusting winds catapulted the Cameron Peak Fire from merely a “really big” fire to the largest in Larimer County's recorded history and the fifth-largest in Colorado history.
The blaze more-than-quadrupled in size from about 24,000 acres on Friday, Sept. 4, to about 103,000 acres on Tuesday, its footprint now almost three times the size of Fort Collins.
Now environmental and water quality experts are bracing for more substantial impacts on the Poudre River and the people who depend on it for drinking water, farming, industry and recreation. Degraded water quality, enhanced flood risk and threats to aquatic wildlife are all distinct possibilities as the blaze takes its toll on a delicate, far-branching river ecosystem that had largely recovered from the impacts of the High Park Fire.
The coming weeks and months will bring more news about what the Cameron Peak Fire will mean for the Poudre River. Until then, some staff of the agencies that monitor the river are in a similar position to the rest of us: Stuck in an anxious waiting game as the blaze continues, temperatures warm up and many details about the fire remain obscured in the ever-present haze.
“There are still so many uncertainties,” said Jen Kovecses, executive director of the Coalition for the Poudre River Watershed. “We’re certain about how big the fire is, but we’re not certain about its intensity on the landscape and what it will look like. That’s going to be the missing puzzle piece that we need to understand the full suite of post-fire impacts from this event.”
MAP: Timelapse shows Cameron Peak Fire exploding over Labor Day weekend
The aftermath of the High Park Fire offers a glimpse, albeit not an ironclad preview, of some impacts that could come from the Cameron Peak Fire. It all starts with the fire burning away the carpet of leaves, twigs, branches and other vegetation on the forest floor, known as “duff.”
“The fire can consume both the forest canopy and the material on the ground, which is a big problem, because now we have bare soil exposed,” said Pete Robichaud, a research engineer with USDA Forest Service's Rocky Mountain Research Station. “That forest floor duff layer is like a big sponge. It absorbs the water when it rains, it allows the water to percolate slowly into the soil — it’s great. Well, now the fire removes that, and when the rain comes, there’s no sponge.”
The other problem is smoke, which can seep into the forest floor and cling to soil particles as it cools and condenses, making them hydrophobic — or water repellent.
The two forces combined can leave the soil vulnerable to even a mild afternoon thunderstorm. Water reverbs off the forest floor and travels downslope to the river, dragging soil, sediment and ash along for the ride.
That’s what happened after High Park, which infamously turned the Poudre black in summer 2012.
“Without the ability to soak up water and temper the intensity of rain events, the system overall became a much flashier system,” said Jill Oropeza, director of sciences for Fort Collins Utilities’ Water Quality Services Division. “You’d see water levels rise really quickly; you’d see material from the hillslopes move into the river channel really quickly, and then the quality would change really quickly as well. You just had tons and tons of ash and sediment that got mobilized into the stream channel and then eventually conveyed downstream.”
The gush of sediment and ash turbocharged turbidity (cloudiness) in Poudre River water, which threatened Fort Collins Utilities’ drinking water supply. Utilities, which typically gets about half its water from the Poudre River and half from Horsetooth Reservoir, shut off its Poudre intake for about 100 days after the High Park Fire.
They did the same on Monday as the Cameron Peak Fire exploded in size, a precautionary measure that is expected to stay in place through the weekend, said Mark Kempton, Utilities’ interim deputy director of water resources and treatment. Water quality staff are unsure how the 14-plus inches of snow that fell on the fire this week will affect the river. On the bright side, snow has less potential than rain to pull a sudden influx of material into the river because snowmelt happens over time.
Utilities staff will be closely monitoring water quality as the fire situation evolves. Their usual alternative won't be available in October and November, though, because of the Horsetooth Outlet Project. The city won't have access to its Horsetooth Reservoir outlet during the long-planned maintenance project on Soldier Canyon Dam but can use an emergency pumping station to access Horsetooth water if needed, Kempton said. As part of the project, the city is asking residents to stop lawn-watering and other outdoor water use from Oct. 1 through the duration of the project.
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Comparing Cameron Peak and High Park
This week's surreal September snowstorm is one of several things that has set the Cameron Peak Fire apart from the High Park Fire. Two other key differences are location, with Cameron Peak burning higher up the canyon than High Park, and time of year. High Park started and was contained in June, allowing for ample summer thunderstorms to send runoff rushing through the Poudre. This time around, we’re heading into the driest part of the year, and then the snow season.
That doesn’t mean the erosion and water quality impacts won’t happen, but it could affect the timing.
“Pretty much anything that burns the tributary to the river is going to affect us,” Kempton said. “It’s just a matter of when. We’ll see it at some point, but are we going to see it really quickly, or are we going to see it in two years?”
The September 2013 flood that followed High Park came over a year later, underlining the potential lag time of fire impacts. The Big Thompson River area bore the brunt of the flood, which began seven years ago on Sept. 11, but the Poudre Canyon also saw significant damage in some areas of the High Park burn scar.
Despite the flood’s devastating impacts, it did one good thing for the Poudre: “It just rinsed it out like a dirty pot in your sink,” recalled LeRoy Poff, a Colorado State University biology professor who's conducted research on the river. “All that ash that was deposited in the river — it was just gone. It was amazing.”
How the fire could impact river life
It’s far too soon to say if something like that will happen in the aftermath of the Cameron Peak Fire, said Poff and others. But Poff did offer a few ecological predictions.
“I expect we’ll see a lot of material accumulating in the streams, and that tends to smother out aquatic life. The streams and rivers are actually pretty resilient, and they can bounce back pretty quickly once that ash gets flushed out. It’s sort of a question of how long that will take.”
If the runoff happens in the fall and spring, when there’s less water in the river to flush it out, it could pose a bigger threat to the many trout species that live and spawn in the Poudre, added Colorado Parks and Wildlife aquatic biologist Kyle Battige. Ash and sediment could cover up fish spawning habitat, lower dissolved oxygen levels or even coat fish’s gills, hurting their chance of survival, he said.
“It’s just harder for the fish to breathe” in that post-fire environment, he said.
The impacts to aquatic life, like everything else, will depend on how exactly the fire burns across the forest. A Burned Area Emergency Response (BAER) team will soon begin the considerable task of assessing the fire footprint. Using a toolbox of satellite imagery and exploration on the ground, the team will feed information into complex models to predict the hydrologic and erosion impacts of the fire and target the most vulnerable areas for post-fire treatment.
The BAER process will demystify the fire’s threat to the surrounding environment and downstream resources, said Robichaud, who conducts research on the models used by BAER teams and the effectiveness of post-fear treatments. Often, that recovery work involves dropping mulch on vulnerable hillsides to prevent erosion after the fire. Agencies and municipalities teamed up to do that kind of recovery work after High Park, zeroing in on the areas most prone to erosion.
The details illuminated through the BAER work — where the fire burns, how intense it is, and the soil type and steepness of terrain in the burn areas — will fill in some of the blanks about how the fire will influence the Poudre River, Kovecses said. Then comes weather, which — if this week is any indication — reliably proves to be a wildcard.
The potential magnitude of the fire’s impacts, combined with its sudden and explosive growth, feels almost like a spiritual affront to the Northern Coloradans who had looked to the watershed as a source of solace during the COVID-19 outbreak, Kovecses said.
“Our communities have been through so much already, between the High Park Fire, the floods, the pandemic, and now this fire,” she said. “It feels like a lot.”
“But if there’s one silver lining, it’s that we have really strong collaborations in this watershed,” she added, noting the ties between community groups, land management agencies, water utilities and others that were strengthened after the High Park Fire. “That will really serve as a foundation to pick up the pieces from this particular wildfire and do what we can to have better outcomes for our communities and for the watershed.”
Jacy Marmaduke covers government accountability for the Coloradoan. Follow her on Twitter @jacymarmaduke. Support stories like this one by purchasing a digital subscription to the Coloradoan.
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As Cameron Peak Fire reaches historic acreage, experts predict damage to Poudre River - Coloradoan
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