BLM Tristate Fuel Break Project aids in fire suppression efforts

The Tristate Fuel Break Project, constructed jointly between the BLM and cooperators, was designed with the goal of enhancing wildfire suppression capabilities near the borders of Idaho, Nevada, and Oregon. On the afternoon of July 13, 2024, the fuel break was put to the test by the Mary Fire, located south of Bruneau, Idaho near Highway 51.

This lightning-caused fire was initially reported at 1,500 acres and was rapidly growing due to extreme fire behavior driven by dry vegetation, high temperatures, and windy weather conditions.

“Dry grass and brush and strong outflow winds from passing thunderstorms resulted in intense fire behavior and rapid growth on the Mary Fire,” said Fire Management Officer for the BLM Idaho Boise District Chris Cromwell. “Firefighters on scene knew they were in for an uphill battle catching the fire due to the observed fire behavior, rugged terrain, and the lack of initial attack reinforcements due to other lightning ignited fires in the area.”

The Tristate Fuel Break, a collaborative effort by BLM Nevada, BLM Oregon, BLM Idaho, Idaho Department of Transportation, and Owyhee County was implemented as a proactive management strategy to establish an interconnected network of fuel breaks along existing road systems at the landscape level. Designed to compartmentalize and catch wildfires at smaller sizes, fuel break treatments modify existing fuels through the strategic removal or replacement of vegetation by mowing, discing, chemical spraying or seeding. The purpose of these treatments is to reduce fire intensity, giving firefighters the ability to suppress wildfires more quickly and safely while protecting critical natural resources on the landscape.

The Mary Fire burned across a 6,227-acre perimeter in an area with an exceptionally high density of sage-grouse leks; there were five leks within the fire boundary and two nearby. This area represents one of the largest intact strongholds of greater sage-grouse habitat within the Northern Great Basin sagebrush-steppe ecosystem. This critical habitat faces significant threats, particularly from post-wildfire conversion to invasive annual grasses. The remoteness of the region further exacerbates the risk, as wildfires can rapidly expand over thousands of acres within a matter of hours.

The fuel breaks on the Mary Fire proved to be effective when the flame front approached Highway 51 and crews were directed to hold the fire on the east side. Firefighters used the fuel break along the highway to burn out ahead of the fire, one engine working from the north and another working from the south.

The fire's behavior changed when it moved into the mow line. By reducing the fuel load, the flame lengths dropped significantly. This allowed crews to safely engage along the highway and burn out in front of the approaching wildfire. The two engines were able to hold the fire along three miles of road with the help of the fuel break.

Well after the main flame front hit the highway, a roughly two-acre spot fire was discovered on the west side of the road in the mow line, most likely due to high winds blowing embers across the line from an area of brush that was too rocky to mow. Crews were able to get around the spot quickly and kept it at around five acres. The rate of spread and flame lengths of the spot fire were lower due to the mow treatment, allowing crews to suppress it quickly and contain it to a mere five acres.

“This fire ending up being caught at 6,227 acres, but it had the potential to be a much larger and more destructive wildfire,” said Cromwell. “The Mary Fire is a great example of how the collaboration, planning and implementation of hazardous fuel breaks before a fire ignites can make a difference by giving firefighters a better opportunity to catch wildfires at smaller sizes in a safer manner.”