After the Flames: How Wildfires Reshape Western Fisheries

When wildfires sweep through the West, the damage doesn’t stop at the tree line. Burned slopes feed the rivers that hold our fisheries, and when fall storms hit those scars, they carry ash, sediment, and debris straight into the water. That surge can cloud rivers, strip out oxygen, and bury spawning beds, sometimes wiping out fish in a single event.

With some of the largest fires in recent memory still smoldering in Arizona, California, and Colorado, the question isn’t just what the land looks like after the flames. It’s what happens next in the rivers that flow below.

A Look at the Burn Zone

Three fires this summer stand out, not only for their size, but for their position above important watersheds:

1. Dragon Bravo Fire: Grand Canyon North Rim, AZ
   • ~145,500 acres burned
   • Ongoing closures on the North Rim
   • Tributaries at risk: Bright Angel Creek, Clear Creek, and Crystal Creek, all feeding directly into the Colorado River corridor
2.  Gifford Fire: Los Padres National Forest, CA
   • ~131,600 acres burned
   • One of California’s largest fires this year
   • Burned into the San Rafael Wilderness, upstream of the Sisquoc, Santa Maria, and Santa Ynez systems, critical habitat for endangered Southern California steelhead
3. Lee Fire: Rio Blanco County, CO
   • ~138,800 acres burned
   • Among the largest in Colorado’s history
   • Triggered fishing closures on sections of the White River, a major trout fishery in the Rockies

     

Fire and Fisheries

When rain falls on a fresh burn scar, water behaves differently. Instead of soaking into forest soil and filtering through plants, it races across bare ground, picking up everything in its path. That runoff delivers ash, fine sediment, organic carbon, and heavy metals straight into streams.

Here’s what that means in practice:

• Turbidity: Rivers can become thousands of times cloudier than normal, smothering gravels and making feeding nearly impossible for sight-oriented fish.
• Nutrients and algal blooms: Extra nitrogen and phosphorus spark algae growth. When algae die, they decay and consume oxygen.
• Organic carbon: Burned material leaches carbon into the water. As it breaks down, oxygen is stripped from the system.
• Dissolved oxygen (DO): Fish breathe oxygen in the water. When DO drops too low, they suffocate.

The 2022 McKinney Fire in Northern California illustrates this process. A post-fire storm sent a wall of ash and mud into the Klamath River, oxygen levels collapsed, and thousands of fish died across nearly 60 miles of river. Three years later, the Klamath is rebounding thanks to major dam removals, but the losses from that event remain part of its story.

Fisheries at Risk

Fires affect fisheries differently during the burn, immediately after, and in the years that follow:

• During a fire: Small creeks are the most vulnerable. Heat, falling debris, or ash pulses can wipe out entire populations in narrow channels. In larger rivers, survival odds improve. Fish can drop into deeper water or find refuge in cooler side channels.
• Immediately after a fire: The first storm is often the most destructive. Debris flows bury spawning gravels, cloud the water, and drop oxygen to lethal levels. Insects die off, leaving less food for fish, and young trout and salmon can be wiped out from whole reaches.
• Years later: Recovery is uneven. Some systems see lasting declines; others benefit from new woody debris and more light, which can increase productivity once water quality stabilizes.

This summer’s major fires highlight different vulnerabilities:

• Dragon Bravo (AZ) threatens high gradient creeks feeding the Colorado River, where flash floods could suffocate fish and smother gravels used for spawning.
• Gifford (CA) burned above the Sisquoc and Santa Ynez systems, some of the last remaining steelhead habitat in Southern California. Heavy sediment pulses could erase the very pools steelhead rely on.
• Lee (CO) has already forced closures on the White River, and its steep slopes make post-fire debris flows a looming concern for trout fisheries downstream.

While the details vary, the pattern is the same: fire reshapes fisheries, first in the headwaters, then downstream.

Resilience and Recovery

The good news: rivers can recover. Many western streams have burned before and bounced back, though the timeline depends on fire severity, storm timing, and restoration work.

Restoration approaches often include:

• Riparian planting to stabilize streambanks
• Sediment traps and erosion controls to slow runoff
• Barrier removals to improve fish passage
• Flow management to buffer heavy sediment loads

Organizations like Trout Unlimited have made post-fire restoration a priority, assisting with reseeding, riparian stabilization, and monitoring efforts following fires such as the Cameron Peak fire in Colorado and multiple California burns. Alongside USFS, watershed councils, and state wildlife agencies, they’re part of the slow, steady work that turns burned slopes back into functioning watersheds.

The Bottom Line

Wildfires increasingly shape the future of western rivers, alongside snowpack and drought. They decide which streams remain viable habitats and which collapse under sediment and oxygen loss. For anglers, recognizing that link is critical. Every fire season is also a fisheries story, and the health of the rivers we depend on is written in the recovery that follows.

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TIME | a reflection with Flip Pallot