How Wildfires Impact Our Local Fisheries
Wildfires and smoke have become an annual reality for Portland residents. As anglers and frequent patrons of public wildlands, we feel the impact on multiple levels.
There's the physical reality, of course. Heavy smoke makes outdoor recreation less pleasant in some cases, and downright hazardous to our health in others. But we also watch anxiously as fire lines move toward our favorite river canyons and alpine lakes, hoping they're spared. We cringe when the roads to popular destinations close, and wonder how long it will be before we can visit once again.
Fire, however, is more than just a destructive force — particularly as it relates to our local fish populations. It's more of a mixed bag. Below, we'll discuss the types of habitats that are most adversely impacted by fire, and those that benefit.
Benefits
Fire, for all the damage it does, is a critical source of regeneration for the natural world. It encourages new growth and creates fertile habitats. And those road closures, as much as they might inconvenience us humans, give nature a chance to reassert itself in areas we've perhaps invaded at an unsustainable scale.
I vividly remember returning to the Collawash River canyon for the first time after 2020's Riverside Fire. A bald eagle had made its nest directly over the road. The fish were bigger and more plentiful. Deer, bears, and cougars were sighted more frequently in the surrounding areas for two years after the closure area reopened. Time away from humanity is never a bad thing for plants and animals.
Aside from a lack of foot traffic, fire can also create food-rich environments for trout depending on a few critical factors. Bigger rivers with a high volume of cool, well-oxygenated water retain the refuge trout require even when riparian cover along the banks has burned. In these instances, we often see the average size of trout go up significantly downstream of burn zones.
Fires create instability, which sends rock, mud, and soil into the rivers, chock full of worms, terrestrials, and nutrients. Fires also encourage low, shrubby growth along the river's edge, which countless other insects make into a temporary home — until spring floods jump over the banks and wash them all into the river below. Everything that lives in the water, from the trout we pursue to the crawdads and baitfish they eat, benefits from all that food. The Lower North Santiam, which suffered significant fire damage in 2020, is a good example of a fishery that has been improved by increased food availability.
Similarly, smaller creeks with high canyon walls — the kind that cast ample shade regardless of tree cover — also seem to benefit from the same phenomenon. Ditto for streams that run through areas of patchwork fire damage — cover and shade in one stretch, followed by high food availability in the next. We've seen this play out in the Gorge, in the aftermath of the 2017 Eagle Creek Fire, and all along the Upper Clackamas. In streams like these, where steelhead smolt exist in high numbers, we've also noticed a significant increase in the size and number of resident rainbow trout. There's enough food in the system to discourage out-migration.
Downsides
Fire tends to have an adverse impact on fish populations at high altitudes, where summertime water levels run perilously low in creeks and streams. Fish in alpine lakes, which tend to be shallow and have modest inflow sources, also suffer.
The Olallie Basin, for example, is home to dozens of lakes that had long been favorite fishing destinations for local anglers. Now, after a series of fires that destroyed nearly the entire basin, many of the lakes stand barren — shallow, warm and coverless. Those with enough depth to retain cool water, like Olallie Lake itself, still hold fish. But the numbers of wild and holdover trout to catch between plantings have dwindled. Other lakes in the basin have experienced full fish kills.
For anglers, fire — and all of the land instability it causes — presents ongoing safety risks that have to be taken into consideration for years after an area has burned. Nature has a miraculous capacity for recovery, but all of that new growth and ground cover often hides how truly scarred the landscape below has been left. Deep ravines and holes where large stumps have burned out might be completely hidden until you've stepped right into them. Thick blackberry brambles will stop you in your tracks when it looks like there's a perfectly clear path down to the water, or back up to the road.
What's Being Impacted Now?
As of now, the active fires are threatening three waterways we guide — Pine Hollow Reservoir, Rock Creek Reservoir, and Badger Creek. The two reservoirs are deep enough for their resident fish to survive and thrive. Badger Creek is a notoriously skinny, shallow tributary and could be in for a difficult recovery, depending on how badly the area burns and whether the fire reaches its namesake lake above.
We will bring you updates as we know more about specific locations. In the immediate term, our priority for the affected areas is to do what we can to support recovery. That means assisting the people who live nearby, many of whom have lost their homes and land or are struggling to access fresh water, and staying away from areas that pose active danger. The last thing any of our overtasked fire and rescue crews need is a stranded fly fisher to save.