Shaded Fuel Breaks Will Not Deliver a Fire Adapted Future in the WUI, but Strategic Placement of Treatments (SPLATs) Can Help

In the face of unprecedented wildfire loss and an increasingly uncertain insurance market, resources and attention have been directed to reducing the wildfire risk facing our WUI communities. Understanding that public attention and budgets are fickle, it is critical that these resources be used in the most effective manner to achieve measurable outcomes. In many WUI communities, including my own, fuel breaks, particularly shaded fuel breaks have become the primary risk reduction measure. Having been involved in the construction of several shaded fuel breaks in the WUI, I have come to believe we are inappropriately and unwittingly applying controversial techniques developed for landscape level management of natural resources in an inefficient and potentially ineffective manner. 

For review, a fuel break is an area of modified fuels designed to reduce fire intensity and provide a location from which suppression efforts can be successful. Traditionally, fuel breaks included the clearance of trees and ground fuels and were constructed in a manner designed to allow for the passage of vehicles. Perhaps the greatest example of this type of fire control measure was the Ponderosa Way, an 800 mile fuel break constructed as part of the New Deal in 1933 and 1934. As an aside indicating how much has changed, this project was undertaken to prevent foothill brush fires from burning into valuable Sierra timber. 

For a fuel break to work as designed, by providing a location from which suppression efforts can be successful, it must include access for firefighting resources and there must be an effective force of available firefighters to make use of the location. All of which includes a temporal component as the opportunity to hold the fire will be lost once fire is over the line. 

Which raises the question of shaded fuel breaks, which are areas of modified fuels designed to reduce fire intensity, but critically, do not include access. In the absence of access, a shaded fuel break becomes a strip of modified fuels, over which fire will inevitably cross as firefighters are unable to rapidly access the critical points in time to make a difference. Early reference to shaded fuel breaks suggests widths of 400’ or less are not effective without suppression efforts and “defensible fuel profile zones” of up to ¼ mile are more effective. When constructed with sufficient depth as roadside clearance, shaded fuel breaks can be very effective since access is assured and fuel modifications build upon the inherent fire control qualities of the existing road. However, many shaded fuel breaks are being built far from roadways and it is unclear how these projects will reduce the probability of wildfire loss in the communities they surround.  

All fuel breaks must be located on the right topography to be effective, and ridge tops are often the most effective place for their construction. However, many communities are not located on or near ridgetops, leading to either fuel break placement far from WUI communities or sub-optimal mid-slope fuel breaks.

Fuel breaks are fixed linear features that have no value if the fire starts and or burns in a location that does not cross the fuel break. As a Marine Corps infantry officer, I look no further than the Maginot Line’s performance in 1940 for the definitive critique of a fixed fortification’s value. Defensive measures of this nature simply lack the adaptability to address dynamic threats.

Critically, there does not appear to be a body of evidence supporting the efficacy of fuel breaks, shaded or otherwise.

In the absence of quantifiable reductions in the potential for wildfire loss, we cannot show our communities the value of the work we have completed and lack a mechanism to link our efforts to insurance access and affordability. Recent studies have shown the potential for up to 75% reduction to the average annual loss calculation used for community level insurance rate setting based on mitigations. However, these benefits can only be achieved through projects carried out in an effective manner. 

This raises the question of what we should be doing instead of fuel breaks. 

In his 2001 paper, Design of Regular Landscape Fuel Treatment Patterns for Modifying
Fire Growth and Behavior, Dr Mark Finney outlined a concept to model and implement “treatment patterns reduce the spread rate or fireline intensity over much of the area burned, even outside the treatment units where the fire was forced to flank”. These have since been implemented at test scale in the Tahoe Basin as Strategic Placement of Treatment (SPLATS).

SPLATS can be created through a variety of fuel treatments to include grazing, prescribed fire, and thinning of vegetation to create a varied fuel mosaic, mimicking the natural state in fire adapted and dependent landscapes such as the American West. This varied mosaic serves as a labyrinth through which fire must find its way, thus slowing its advance and buying time for a firefighting response to protect homes and communities. The additional time gained through a reduced rate of spread, also opens opportunities to manage a naturally occurring fire for beneficial outcomes. Further, by virtue of their distributed nature, SPLATS can be used to minimize disruptions in environmentally sensitive areas. 

When combined with defensible space in the form of rigorous fuel reduction efforts within 100’ of homes and thoughtful home hardening retrofits at actuarially significant levels of adoption, the combination of mitigations sets the stage for significant reductions in potential wildfire loss experience. 

This is no secret weapon, the New Yorker featured them in a 2019 article, yet we keep putting in shaded fuel breaks without any validation that they will work. 

As fire service professionals, we are charged with protecting our community from a number of perils, one of which is wildfire. Part of protecting a community is ensuring the limited resources available to mitigate risk, in the area of our expertise, are used in the most effective manner. Another part of protecting our communities is ensuring our work is focused on beneficial outcomes and not performative acts which may provide a false sense of security. It is time to follow the science through advocacy and implementation of risk reduction measures that will work.