From The Fort Collins Coloradoan (Jacy Marmaduke):
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.”
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.”