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FIRE FACTS: What is containment?

September 2, 2023
News article

Firefighters control a fire's spread by enclosing it within "containment lines" where there's no fuel to feed it. Find out how this helps stop wildfires.

The Tiger Island Fire is over 30,000 acres. That means the fire perimeter encompasses that acreage. It does not mean the acreage is all currently burning. In fact, most of the acres are "black."

But, fire usually burns in a mosaic pattern, so there are pockets of unburned fuel within the fire perimeter. Also, we are experiencing "needle cast," where green trees that have been scorched begin to shed their needles and leaves, providing additional fuel for the fire. So, if a hot area within the fire perimeter can reach any of those fuel sources, it can start to burn. If there is wind gust and if the new burning area is close to the control line, it can throw embers and start a "spot fire" outside the lines.

Portions of the fire perimeter are not considered contained until there is a high confidence the fire will not cross that section of line.

Because the chance of spot fires has been high (heat pockets, winds, and dry fuel), we have not felt confident enough to increase containment. That doesn't mean the situation is not improving though! Every day, we work hard putting water on hotspots and widening dozer lines, decreasing the chance anything gets through. We are adding "black" (contained sections) to the line, as we secure each section and build that confidence.

Right now, our goal is 100% containment.