Development in the WUI - A Collection of Resources
Consider several of the most devastating fire disasters of the last century. In August 2023, the wildfire-initiated urban conflagration of Lahaina, Hawaii, damaged or destroyed more than 2,200 structures and killed 98 people. In December 2021, the Marshall Fire sparked conflagrations in Superior and Louisville, Colorado, destroying 1,084 structures and killing two. In September 2020, the Almeda Drive Fire in the communities of Talent and Phoenix, Oregon, destroyed 2,600 homes and killed three. In November 2018, the Camp Fire initiated ignitions in Paradise, California, destroyed 18,804 buildings, and killed 85. In November 2016, fires spread through Gatlinburg and Pigeon Forge, Tennessee, destroying 2,460 structures and killing 14. These fire disasters burned in vastly different environments. But all had human causes (power lines contributed to at least three), were near communities, occurred during extreme wind events, then inflicted their damage as urban conflagrations. Almost all destruction occurred within the first 12 hours after ignition. These fires immediately overwhelmed wildland and structural firefighting efforts, which were largely ineffective during the initial and extreme phase of the fire. Further, all these fires occurred since 2016. It’s clear that structures and whole communities were vulnerable to ignition and burning—irrespective of what initiated the fires.
Our results show that 57% of structures (homes, schools, hospitals, office buildings, etc.) are located in hazard hotspots, which represent only a third of CONUS area, and ∼1.5 million buildings lie in hotspots for two or more hazards. These critical levels of exposure are the legacy of decades of sustained growth and point to our inability, lack of knowledge, or unwillingness to limit development in hazardous zones. Development in these areas is still growing more rapidly than the baseline rates for the nation, portending larger future losses even if the effects of climate change are not considered.
Description: As communities across the U.S. face increasing threats from wildfire, there is also a growing interest in land use planning as a strategy to reduce risk and foster more resilient outcomes. Land use planning provides a variety of tools, such as growth management plans, subdivision regulations, or wildland-urban interface (WUI) codes that can be applied in wildfire-prone areas. These tools can support public safety and emergency response, direct growth away from high hazard areas, and can complement other fire adapted activities such as vegetation management. However, selecting the appropriate tools and integrating them with other approaches often takes consideration of many factors—such as existing state requirements, potential shifts in demographic and development patterns, political will, and enforcement capacity. This webinar will provide a brief history of planning in the WUI for context, and highlight different planning tools and implementation strategies available to state and local governments—including examples from across the West.
Presenter: Molly Mowery, AICP, Executive Director, Community Wildfire Planning Center
Wildfire across the western US has increased in size, frequency, and severity since the 1950s. These changes are closely linked with increases in temperature and an increased frequency and intensity of drought. Historically, frequent low to moderate-severity fires dominated the fire regime in many western forests, maintaining low-density forests with larger trees. A history of fire exclusion, logging activity, grazing, and invasive species has led to an uncharacteristic build-up of forest fuels in many areas, increasing the susceptibility to large-scale, high-severity wildfire. The US has a history of fire suppression efforts that has exacerbated the problem by increasing the density of trees and fuel availability, and reduced the overall area burned by wildfires to levels that are below those that occurred before the beginning of the 20th century.
The western US is also experiencing larger, more severe fires that are often near communities. In recent decades, the build-up of forest fuels, a warmer and drier climate, and expansion of the wildland-urban interface (WUI) into forested areas has changed western landscapes and increased wildfire hazard. Federal policy and management have primarily focused on fire suppression and more recently on fuels reduction on some federal lands. Forest restoration and fuels reduction projects have had positive ecological impacts; however, the pace and scale of forest treatments is not keeping up with heightened wildfire activity across the West.
The WUI is often synonymous with fire risk to buildings, but this research suggests that this is not the case in all fire-prone states. While fire outreach was often present near areas where buildings are destroyed by wildfire, many communities are established after major fires.
View research brief.
We have been studying the WUI in the U.S. for more than 10 years, looking at where WUI areas were once located, where they are now, and where we expect them to be in the coming decades. Our new data set provides the first high-resolution data on WUI change from 1990 to 2010, revealing how housing growth and wildland vegetation have combined over time. We developed new algorithms that converted the decennial Census standalone data into a consistent dataset on housing growth across the conterminous U.S.
The WUI in the United States grew rapidly from 1990 to 2010 in terms of both number of new houses (from 30.8 to 43.4 million; 41% growth) and land area (from 581,000 to 770,000 km2; 33% growth), making it the fastest-growing land use type in the conterminous United States. The vast majority of new WUI areas were the result of new housing (97%), not related to an increase in wildland vegetation. Within the perimeter of recent wildfires (1990–2015), there were 286,000 houses in 2010, compared with 177,000 in 1990. Furthermore, WUI growth often results in more wildfire ignitions, putting more lives and houses at risk. Wildfire problems will not abate if recent housing growth trends continue.