Should Colorado adopt a statewide wildland-urban interface code?

State preemption is at the center of a national debate on managing development

This week Colorado state senator Lisa Cutter (D) will introduce a bill that would preempt local control over land-use decisions to create a statewide building code for development in the wildland-urban interface (aka the WUI, or the ‘zone of transition between unoccupied land and human development). The law would empanel a statewide board to define the boundaries and characteristics of the wildland-urban interface in the state, and impose a statewide building code for development in different wildfire zones. This is not a new idea - policymakers in Colorado have been discussing the possibility of statewide WUI code for over a decade. A similar measure came close to passing in 2022, but was ultimately tabled after lawmakers reached a legislative impasse.

The Marshall Fire - which swept through Boulder County in late 2021 and destroyed 1,084 homes - has lent new urgency to the debate. The Marshall Fire was most destructive wildfire in state history and was just one of many large wildfires that Colorado has suffered over the past 15 years. Those disasters include the Fourmile Canyon Fire (168 homes destroyed), Waldo Canyon Fire (346 homes), Black Forest Fire (486 homes destroyed) and the East Troublesome Fire (366 homes).

A neighborhood in Superior, Colorado after the Marshall Fire in 2021. Photo by Kevin J. Beaty of Denverite

Scientists expect that Colorado will suffer more frequent and destructive wildfires in the future, for two fundamental reasons. First is the sheer volume and scale of new development in the WUI. Research from the University of Wisconsin Madison shows that the number of structures in Colorado in the WUI has more than doubled in the past 30 years, from 573k in 1990 to nearly 1.1 million in 2020. This trend is reflective of other states in the Mountain West. The other reason is climate change, which is expected to make Colorado hotter and drier for longer periods of time each year - all key ingredients in wildfire frequency, severity and duration.

Regulating WUI Development

There is a large body of research on reducing the impact of wildfires on development that draws on scientific studies and practical experience. I link a few recommended big-picture pieces in the ‘learn more’ section below. There are a few bottom-line findings:

• The best way to avoid a wildfire disaster is to not develop in areas prone to fire;

• The next best way to avoid a wildfire disaster is to build smartly in fire prone areas, using strategies like clustering development, avoiding topographical features like steep slopes, requiring ignition resistant materials and fire suppression technologies, and/or creating defensible space around structures.

• Another important consideration for governments is whether people living, working or recreating in WUI areas can access emergency services in the event of a fire, and whether emergency services can reach development.

WUI codes enshrine many of the bottom-line best practices described above. Like their cousins, floodplain development codes, WUI codes typically start by defining where wildfire risk is, and then requiring development in different ‘zones’ of risk to take specific steps. The National Institute of Building Sciences estimates that for every $1 invested in the adoption of a WUI code, communities would save $4 in eventual disaster losses.

How development density relates to WUI area identification. Source: Community Planning Assistance for Wildfire (CPAW).

Sounds great, right? We know where risk is highest, we know what steps we should take to reduce it, and we have a policy mechanism to spur action. Where things get tricky is with the question of who should decide whether to adopt a WUI code and what should be in it.

I will spare you the long lecture about the police power, the Standard Acts and the 10th Amendment. Suffice it to say that in the United States, states have the power to regulate land-use, and all of them have ceded that authority to local governments in one way or another - an arrangement we call local control. The exact arrangement varies by state, but a key point of contention everywhere is state preemption. That is, when can (or should) the state supersede local authority regarding land-use? For example, if a local government refuses to regulate development in the WUI according to basic hazard mitigation principles, can (or should) the state supersede their authority to ensure those standards are followed?

State preemption has been a hot topic in the housing world lately, after California and Oregon preempted local land-use planning to ban single-family zoning and as other states are considering similar laws in an attempt to increase housing production. Preemption shows up in other land-use conflicts as well. For example, the Texas State government preempted local control over the siting of oil and gas facilities in 2015, after the City of Denton voted to ban gas drilling within its municipal boundaries.

In the case of WUI codes, states like Colorado have thus far kept control with local governments, who critics of a statewide code argue are better able to create and enforce codes that suit their context. And many places in Colorado have done just that. For example, Boulder County has a decades long WUI code that was recently amended to include development everywhere, not just in the foothills and mountains (a change created after the Marshall Fire). The Town of Vail requires the use of non-combustible or ignition resistant materials in nearly all construction in its WUI areas and landscaping that is designed to minimize the spread of fire. The City of Colorado Springs similarly enforces a WUI code for development in its fire hazard areas, and those requirements supersede any less-restrictive HOA or neighborhood covenant requirements. And so on. There are at least a dozen towns, municipalities and counties in the state that have adopted a WUI code, and more that have community wildfire protection plans in-place.

Critics of a statewide code worry about other things, too: whether a ‘one-size-fits-all’ approach will work in a geographically diverse state like Colorado; the impact on construction costs; the administrative burden of adopting and enforcing a WUI code, especially for rural counties; and the precedent set by preempting local control over land use regulations, to a name a few.

Proponents of a statewide code argue that establishing minimum standards for the whole state is important, because many communities do not have any wildfire codes at all, or have adopted weakened codes that are not terribly effective. Adopting a statewide code should also bring down construction costs, they argue, because builders and their supply chains will adjust to a single statewide standard. There are also public safety arguments; that if local governments are not willing or able to protect public safety through the adoption of codes, then the state should ensure a minimum ‘floor’ of protection that applies equally. Lastly, proponents point to federal grant programs - most notably the Building Resilient Infrastructures and Communities (BRIC) grant program from FEMA - that reward states that have adopted standardized codes.

While we have plenty of evidence that wildfire building codes are effective, I haven’t seen studies that compare states with mandatory codes versus those with local control (if you know of any such studies, please message me!) For now, what do you think about state vs. local control over development regulations in the WUI? I welcome your thoughts or feedback, in the comments here or on Twitter.

Learn More

• The U.S. Fire Administration (2023) Wildfire and WUI Blog.

• The American Planning Association (2019) Planning in the Wildland-Urban Interface. PAS Report 594.

• Planning for Hazards (2023) Wildland-Urban Interface Code Profile and Webinar.

• Community Wildfire Planning Center WUI Planning Hub.

• Firetopia - a toolkit for using land-use planning to reduce wildfire risk.

• International Code Council’s 2021 International Wildland-Urban Interface Code (IWUIC).

• Intini, Paolo, Enrico Ronchi, Steven Gwynne and Noureddine Bénichou (2020). Guidance on Design and Construction of the Built Environment Against Wildland Urban Interface Fire Hazard: A Review. Fire Technology 56: 1853-1883.

What Else I’m Reading This Week

• Like all of you, I’m watching in horror as the death toll in Turkey and Syria continues to rise after the twin 7.8 and 7.7 magnitude earthquakes struck on February 6th. This is a global tragedy that will take years, or decades, to recover from. I’ll write more later as disaster scientists begin publishing research on the event, but so far I’m paying most attention to news about the building industry and lax enforcement of building codes and standards.

• One of the bigger and more abrupt changes at Elon Musk’s Twitter is changes to its application programming interfaces (APIs) - the connections that allow 3rd party software to communicate with the platform. In the disaster science corner of the world, researchers and practitioners use Twitter data for everything from data mining to producing real-time awareness of rescue efforts. Changes to the API will clearly impact these modes of engagement…after the Turkey earthquake, for example, volunteer ‘crisis mappers’ ran into a myriad of issues that limited their effectiveness.

• Anna Weber at the Natural Resources Defense Council, Inc. wrote this terrific piece on FEMA’s Building Resilient Infrastructure and Communities (BRIC) grant program and the ‘capacity gap’ between program availability and community uptake.