Significance Recent wildfire events throughout the world have highlighted the consequences of residential development in the wildland-urban interface (WUI) including hundreds to thousands of homes burned during a single wildfire to, more tragically, firefighter and homeowner fatalities. Despite substantial investments in modifying wildland fuels near populated areas, losses appear to be increasing. In this article, we examine the conditions under which WUI wildfire disasters occur and introduce a wildfire risk assessment framework. By using this framework, we examine how prefire mitigation activities failed to prevent significant structure loss during the Fourmile Canyon fire outside Boulder, CO. In light of these results, we suggest the need to reevaluate and restructure wildfire mitigation programs aimed at reducing residential losses from wildfire.

Wildfires can result in significant, long-lasting impacts to ecological, social, and economic systems. It is necessary, therefore, to identify and understand the risks posed by wildland fire, and to develop cost-effective mitigation strategies accordingly. This report presents a general framework with which to assess wildfire risk and explore mitigation options, and illustrates a process for implementing the framework. Two key strengths of the framework are its flexibility-allowing for a multitude of data sources, modeling techniques, and approaches to measuring risk-and its scalability, with potential application for project, forest, regional, and national planning. The specific risk assessment process we introduce is premised on three modeling approaches to characterize wildfire likelihood and intensity, fire effects, and the relative importance of highly valued resources and assets that could be impacted by wildfire. The spatial scope of the process is landscape-scale, and the temporal scope is short-term (that is, the temporal dynamics of succession and disturbance are not simulated). We highlight key information needs, provide guidance for use of fire simulation models and risk geo-processing tools, and demonstrate recent applications of the framework across planning scales. The aim of this report is to provide fire and land managers with a helpful set of guiding principles and tools for assessing and mitigating wildfire risk.

Over the last two decades wildfire activity, damage, and management cost within the US have increased substantially. These increases have been associated with a number of factors including climate change and fuel accumulation due to a century of active fire suppression. The increased fire activity has occurred during a time of significant ex-urban development of the Wildland Urban Interface (WUI) along with increased demand on water resources originating on forested landscapes. These increased demands have put substantial pressure on federal agencies charged with wildfire management to continue and expand the century old policy of aggressive wildfire suppression. However, aggressive wildfire suppression is one of the major factors that drive the increased extent, intensity, and damage associated with the small number of large wildfires that are unable to be suppressed. In this paper we discuss the positive feedback loops that lead to demands for increasing suppression response while simultaneously increasing wildfire risk in the future. Despite a wealth of scientific research that demonstrates the limitations of the current management paradigm pressure to maintain the existing system are well entrenched and driven by the existing social systems that have evolved under our current management practice. Interestingly, US federal wildland fire policy provides considerable discretion for managers to pursue a range of management objectives; however, societal expectations and existing management incentive structures result in policy implementation that is straining the resilience of fire adapted ecosystems and the communities that reside in and adjacent to them.