What does it mean when a fire is contained?

As the  Dixie Fire sits at more than 960,000 acres and 86 percent contained, some questions that commonly come up are what exactly does containment mean? When will the fire be contained? Once it’s contained, it’s out, right?

The Lassen and Plumas National Forests recently shared some insight on what it means for a fire to be contained.

Essentially, contained means the measure of fire line that can be reasonably expected to stop the fire’s spread, whereas controlled means the fire is truly out.

“Containment is a measure of the amount of line around a wildfire that can reasonably be expected to stop the fire’s spread. It’s as much a measure of linear footage as it is confidence.

“While it might seem to take several days before there’s significant containment on any given fire, that number oftentimes grows rapidly as plans come together in several ways to build both line and confidence.

“First, the line must be established. Whether built by men and women on hand crews using shovels, axes, saws and Pulaskis or bulldozers, excavators and masticators, a solid line free of consumable vegetation and down to unburnable mineral soil is what stops a fire’s growth.

“Many times, the line must be constructed some distance away from the fire’s edge in order to protect the life and safety of crews on the ground. This indirect line then can be used as a starting point for strategic firing operations. These operations are coordinated with multiple personnel groups and done only under the most conducive conditions in order to ensure success and safety. Firing operations are intended to take fuel away from the advancing fire, reducing the severity of the fire’s impact and building a larger line by blackening the available fuels on firefighters’ terms. It is, quite literally, fighting fire with fire.
Once a fire reaches a high percentage of containment, it might stay at that level for weeks, even months, as pockets of unburned fuels inside the lines continue to burn. Again, containment is just as much a measure of confidence as it is miles of line on the ground.

“Now that the fire is 100 percent contained, it’s out, right?  Unfortunately, no.  Contained and controlled are two different things.  Controlled is totally out, not coming back, no flames, no smoke. Some fires can linger at 100% containment until winter rains or snow arrive and bury any and all smoldering logs, embers or ash. And even then, under the right conditions, fires can show themselves once spring comes, snow melts and the tiniest of hot ember finds just enough air and fuel to show smoke. Rare as it might be, it does happen.”