What’s the Largest Wildfire in Idaho’s History?

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the Largest Wildfire in Idaho's History

The 2019 Idaho wildfire season was relatively mild compared to recent years, but the Pacific Northwest is no stranger to wildfires.

Idaho, in particular, has seen its share of massive wildfires. Regular bouts of dryness combined with beautiful but rough terrain and shrubby steppes make Idaho especially vulnerable to wildfires.

While you can see all of the current fires on a frequently updated Idaho wildfire map, one wildfire stands out above all others as the largest wildfire in Idaho’s history: The Great Fire of 1910.

the Largest Wildfire in Idaho's History


The Largest Wildfire in Idaho’s History

The Great Fire of 1910

The Great Fire of 1910 was the largest wildfire in Idaho’s history. It is also believed to be the largest wildfire in U.S. history, raging unchecked across three million acres in northern Idaho and western Montana. To put this into perspective, that’s approximately the size of the state of Connecticut. The loss of timber alone was worth an estimated billion dollars.

According to the Forest History Society, the wildfire killed at least 87 people, mostly firefighters on the front lines, and destroyed entire towns along the way. Most of the devastation occurred in a single six-hour period.

It occurred in the summer of 1910 when a devastating series of forest fires swept over Idaho, Montana, and Washington, culminating on August 20-21 in what is known as the “Big Blowup.” Many books have been written about this tragic event, with eyewitness accounts recording forever the horror of that experience first-hand.

The Cause

While no one single cause was ever officially established, a combination of events played into what eventually became the largest wildfire in Idaho’s history.

To begin with, 1910 was the driest year anyone could recall at that time, setting the stage for what was to come.

The first fire of the 1910 wildfire season broke out in the Blackfeet National Forest in northwestern Montana on April 29. By June there were up to 100 small fires in several locations. On the night of July 15, an electrical storm touched off more fires.

Additional contributing factors included accidental fires started by homesteaders, loggers, and campers.

The greatest contributor, however, is believed to have been the then-new Chicago, Milwaukee and Puget Sound Railway. The new train followed the St. Joe River east from St. Maries to Avery, Idaho, winding through the densely timbered Bitterroot Mountains, and coming out near Taft, Montana. A 1911 report later estimated there were more than 100 fires ignited by the red-hot cinders that flew into bone-dry forests. The railway hired “spotters” to douse the flare-ups along the tracks, but it quickly became too much for them.

the Largest Wildfire in Idaho's History

By August 19 between 1,700 and 3,000 fires were burning in northern Idaho and western Montana. Then, on Saturday afternoon, August 20, “all hell broke loose.”

Hurricane-force winds roared across eastern Washington and into Idaho and Montana forests, fanning the embers and causing flames to spread rapidly. “Trees by the millions became exploding candles,” the U.S. Forest Service said. “Millions more trees, sucked from the ground, roots and all, became flying blowtorches.”

By noon on the 21st, darkness from the smoke reached north to Saskatoon, Saskatchewan, south to Denver, and east as far away as Watertown, New York. To the west, it was so dark that ships 500 miles out to sea were unable to navigate by the stars. According to the Weather Service, the smoke from the Great Fire spread a third of the way around the world.

The extreme scorching heat of the sudden blowup is attributed to the Western white pine forests that covered much of northern Idaho at the time. Hydrocarbons in the trees’ resinous sap boiled out and created a cloud of highly flammable gas that blanketed hundreds of square miles, which then spontaneously detonated dozens of times, each time sending tongues of flame thousands of feet into the sky and creating rolling waves of fire that utterly destroyed everything in its path.

After what must have seemed like an eternity in those two days of terrifying and uncontrollable devastation, the fire was finally stopped by rain.

The Aftermath

Coming only five years after the U.S. Forest Service’s establishment, the Great Fire of 1910 made a deep and lasting impact on the agency. Three future Forest Service chiefs were directly involved in the Big Blowup, as were several other men who would later influence the agency’s fire protection policy. It brought forest fire issues into the public arena and led to new fire prevention and suppression policies, policies that still influence fire management around the world today.

In the aftermath of the fire, the U.S. Forest Service received considerable recognition for its firefighting efforts, along with a much larger budget. The outcome was to highlight firefighters as public heroes while raising public awareness of national nature conservation.

the Largest Wildfire in Idaho's History

Idaho Soda Fire

The 2015 wildfire season was a record for the U.S. as a whole, and in Idaho, which suffered its worst fire season in nearly 90 years, the Soda Fire was one of the largest.

During the summer of 2015, the Soda Fire burned nearly 280,000 acres of entire ecosystems just southwest of Boise, Idaho, along the border of southern Idaho and eastern Oregon. It spread rapidly, affecting vegetation, wildlife, ranchers, and local communities.

The Cause

The Soda Fire was caused by a lightning strike on August 10, 2015. The wildfire quickly burned its way across southwest Idaho and eastern Oregon, feeding on dry sagebrush, cheatgrass and mountain mahogany. The greatest expansion occurred on August 12, when it grew from 78,000 acres to 120,000 acres.

When it was over, it had burned through:

  • over a quarter-million acres of sagebrush,
  • 41 grazing allotments,
  • important habitat for many species,
  • a wild horse management area, and
  • recreation areas.

Ongoing cooperative partnership efforts to rehabilitate and restore these rangelands have served as an outdoor laboratory to understand what it takes to restore the land.

the Largest Wildfire in Idaho's History

The Aftermath

The biggest threat in the aftermath of wildfires in sagebrush country is the takeover of invasive, non-native annual grasses. Invaders like cheatgrass also dry out faster than native plants and can, therefore, extend the fire season.

The spread of invasive annual grasses has several negative effects, including:

  • disrupting water cycles,
  • degrading wildlife habitat,
  • reducing the resiliency of the landscape to withstand future threats,
  • degrading outdoor recreation opportunities, and
  • reducing forage production for livestock.

Since the Soda Fire affected both public and private lands, a collaborative effort was vital to restore the ecosystem balance.

The Bureau of Land Management developed an Emergency Stabilization and Rehabilitation plan to treat the areas damaged by the Soda Fire. The agency assembled a team of natural resource specialists from multiple disciplines to assess the damage. They could then design and implement a variety of treatments to restore the altered ecosystem balance.

The ESR plan targeted the resistance and resilient concept to ensure the burned areas are resistant to invasive annual grasses and more resilient to future droughts or wildfires.

According to Brandon Miller of the USFWS Partners Program, “The ongoing cooperative monitoring is one of the biggest successes of the Soda Fire. It allows us to be surgical in applying the right treatments in the right areas, and also make sure the treatments are working.”

Lasting Impact

In the wake of both devastating and record-setting wildfires in Idaho, important new initiatives were born. The challenges are ongoing and multi-faceted, but the common goals of prevention as well as managing the land after a fire remain the focus.

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