Yosemite Valley with a layer of dense smoke during controlled burns.

Yosemite Valley On Fire

By Jeff Fennell
11/10/2023, 04:22 AM

Yosemite National Park Management is afraid of forest fires, and understandably so. I can think of no more a devastating way to lose acres upon acres of some of the most beautiful forest scenery in the world than to have it all burn to a crisp, when it's well within human control to prevent that fate. Historically park management made efforts to prevent such a demise, monitoring and swiftly suppressing all fires within the park, manmade and natural.

Over time, this lack of fire led to overgrown forest areas accumulating an abundance of flammable material, leading scientists and park managers to realize the ecosystemic benefits of regularly occurring natural forest fires. In addition to clearing out dead, flammable vegetation, as a secondary benefit fires also enrich the soil with nutrients to encourage new growth.

In the 1970s, Yosemite implemented a Fire Management program which seasonally performs prescribed burns to cull dead vegetation, reducing the frequency and magnitude of naturally occurring forest fires.

The scope of these burns can vary depending on the time of the year and the area of the park, but I've happened to visit the park a few (2) times while burns were taking place in The Valley.

The first time was in May of 2022, when crews were performing pile-burns. Driving around The Valley, you could see evidence of the day's and week's burns, long trails of smoldering ash piles every 15-30 feet culminating in the current moment's flaming pile, and just beyond it, the queue of freshly aggregated fuel piles of dead branches and shrubbery awaiting their turn.

Yosemite National Park Fire Management about to set fire to a brush pile during controlled burns.
Crews spray water in advance of controlled burns.
Fire crew in Yosemite National Park sets fire to a fuel pile during controlled burns.
Spent fuel piles throughout Yosemite National Park during controlled burns.
Spent fuel piles throughout Yosemite National Park.
Fire crew in Yosemite National Park sets fire to a fuel pile during controlled burns.
Raging fire during controlled burns in Yosemite National Park.
Fire crews stood idly by, setting fire to each pile using this tiny red can, passively tending to it (from what I could tell, supervising more than anything), moving along to the next pile once the previous one reduced to an acceptable level.

The second time I was there during controlled burning was the last weekend of October, 2023.

Interestingly the strategy of the fire management team seemed much different this time. Rather than individual burn piles this time I witnessed man-made lines of fire slowly crawling along across the park floor in various places, more akin to how a natural fire would burn. As you can imagine, the fire management crews were out in greater numbers for these burns, and seemingly much more focused on keeping the fire under control. Some of these fires were set to allow individual trees (seemingly diseased and/or decaying) to burn while still standing.

While I didn't take too many photos in the valley during this trip, mostly because the smoke in the air caused my lungs to burn after only a few minutes outside of my car, what I did manage to capture this time around was the impact on the air quality in the Valley during these rounds of burns. I don't have any official metrics giving insight into the air quality for the day, but what I do have are some photos to give you a visual sense of just how much smoke was in the air:

Tunnel view at sunrise:

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El Capitan at 8 am

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Rays of sunlight poking through trees

Yosemite Valley Fire crews prepare for scheduled burns.

I don't know if the sheer quantity of material burned was higher during this trip, if I came towards the tail end of the burn cycle, so there was more residual particulate in the air, or if there are different acceptable amounts of particulate matter in the air depending on the time of the year and time of day that the burns take place, or entirely other factors altogether.

What I do know is that the natural role of forest fires reveals such an interesting dichotomy in nature - to burn is to beautify; to destroy is to protect and enrich; to inflame is to suppress; to kill off is to give new life. Above all, I find it fascinating that one of the greatest tools that man has in preventing devastating forest fires is fire itself.

For the sake of transparency in this new age of Generative AI, I'd like to note that none of the photos I've shared here were created or altered using generative AI.