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Farmington Wildland Urban Interface
OVERVIEW
Wildland Urban Interface (WUI) is defined by the United States Fire Administration as a zone of transition between unoccupied land and human development. This can also be described as an area where structures and other land development intermingle with vegetation such as trees, plants, and native wildlife. Increased urban development in WUI areas combined with changes in wildfire behavior, record breaking heat and drought, and climate change has intensified the need to better understand and manage the wildland urban interface area. The impacts of wildfires vary by size and location, typically resulting in devastating losses.
PRIMARY THREATS TO HOMES DURING WILDFIRE
Embers (firebrands) and small flames are the primary ignition source for the majority of WUI home fires. Embers are burning pieces of airborne wood and/or vegetation that can be carried more than a mile through the wind. These can cause spot fires and ignite homes, debris and other objects.
Wildland fires can ignite buildings within a WUI in a number of ways and depend greatly on the characteristics of the wildland (fuels, terrain, weather), the characteristics of the community (construction materials, building designs, housing density, landscaping), and the characteristics of the interface (separation distance, physical barriers).
Farmington is among thousands of cities across the U.S. that are working to prevent wildfires in their communities. Based on data from the National Association of State Foresters and the U.S. Department of Homeland Security:
- More than 60,000 communities in the United States are at risk for WUI fires. (LINK)
- Between 2002 and 2016, an average of over 3,000 structures were lost to WUI fires each year in the U.S. (LINK)
- The WUI area continues to grow by approximately 2 million acres per year. (LINK)
- Relative to the total houses in the state, New Mexico has between 60.1 - 82.6% of houses in a WUI area. (LINK)
There are methods for homeowners to prepare their homes to withstand ember attacks and minimize the likelihood of flames or surface fires from touching the home or attachments. The National Fire Protection Association (NFPA) states that homes ignite due to the condition of the home and everything around it, up to 200' from the foundation, called the Home Ignition Zone (HIZ).
FARMINGTON WILDLAND INTERFACE MAP
By mapping Farmington's WUI areas, a spatial record has been created to represent areas where structures and other human development coincide with vegetation within and around the boundaries of the city. The Farmington Wildland Urban Interface Map can be used as a tool to help identify fire risks in order to assess and mitigate impacts of development on wildlands and for protecting homes from natural hazards. The map below was put together by the City of Farmington Planning Division with the contribution of several local and federal agencies including the Farmington Fire Department, San Juan County, and the Bureau of Land Management Farmington Field Office. The Farmington WUI map defines wildfire risks as either "low to moderate" and "high", based on a number of factors including structure density and vegetation levels. An additional surface management layer has been added to provide information on land ownership within and around Farmington.
-FARMINGTON WILDLAND URBAN INTERFACE MAP LINK-
WIU maps can be extremely helpful in tracking changes in wildfire over time. The Wildland-Urban Interface Change Map put together by Silvis Lab through the University of Wisconsin provides insightful data on how WUI areas have grown through the years.
Get Informed. Prepare your home for wildfires. Also available in Spanish
PROTECTION FROM WILDFIRE
Wildfire will find the weakest links in the defense measures you have taken on your property.
The primary determinants of a home's ability to survive wildfire are its roofing material and the quality of the "defensible space" surrounding it. Consider the following steps in setting up your home's defensible space. These precautions should certainly be taken in building a new residential home, however many can also be used to increase an existing home's resistance to wildfire.
- Use fire-resistive materials (class B or better rating, preferably Class A).
- Use a fire-resistant roofing material, not wood or shake shingles.
- Clearing or reducing fuels and vegetation around the home will not only slow the spread of wildfire towards the structure, but also provides room for firefighters to do their jobs in case of fire.
Additional information can be found here on creating and maintaining your home's defensible space: Creating Wildfire-Defensible Zones
THE HOME IGNITION ZONE
USDA Forest Service fire scientist Jack Cohen developed the concept of the home ignition zone in the late 1990s and is based on research into how homes ignite due to the effects of radiant heat. The Home Ignition Zone is divided into three zones.
IMMEDIATE ZONE - The immediate zone includes the home and the area 0-5' away from the furthest attached exterior point of the come. This is the most important zone to take immediate action on as it is the most vulnerable to embers. See Fact Sheet
- Clean roofs and gutters of dead leaves, debris and pine needles that could catch embers.
- Replace and/or repair loose or missing shingles and damaged or loose window screens to prevent ember penetration.
- Prevent ember passage through vents in the eaves and attic by installing 1/8 inch metal mesh screening.
- Move any flammable material away from wall exteriors- mulch, flammable plants, leaves and needles, firewood piles- anything that can burn. Remove anything stored underneath decks or porches. Keep flammable debris a minimum of 50 feet from the house, preferably on the uphill side.
- Choose fire resistant building materials whenever possible.
INTERMEDIATE ZONE - The intermediate zone expands 5-30' from the furthest exterior point of the home.
- Clear vegetation from under large stationary propane tanks.
- Create fuel breaks with driveways, walkways/paths, patios, and decks.
- Keep lawns and native grasses to a height of four inches.
- Remove ladder fuels (vegetation under trees) so a surface fire cannot reach the crowns. Prune trees up to six to ten feet from the ground.
- Space trees to have a minimum of eighteen feet between crowns with the distance increasing with the percentage of slope. Tree placement should be planned to ensure mature canopy is no closer than ten feet to the edge of a structure.
- Tree and shrubs in this zone should be limited to small clusters of a few each to break up the continuity of the vegetation across the landscape.
EXTENDED ZONE - The extended zone expands 30-100', out to 200'. The goal is not to eliminate fire but to interrupt fire's path and keep flames smaller and on the ground.
- Dispose of heavy accumulations of ground litter and debris.
- Remove dead plant and tree material.
- Remove vegetation adjacent to storage sheds or other outbuildings within this area.
- Thin trees so that trees 30-60 feet from the home have at least 12 feet between canopy tops and trees 60-100 feet from the home have at least 6 feet between the canopy tops.
FIREWISE PLANT MATERIALS
FIREWISE landscaping can be aesthetically pleasing while reducing potential wildfire.
Many native plants are highly flammable during different seasons of the year. Left unmanaged, they can accelerate the spread of wildfire. Plants that are more resistant to wildfire have one or more of the following characteristics:
- They have a high moisture content (the most important factor governing is volatility).
- They grow without accumulating large amounts of combustible dead branches, needles, or leaves.
- They have low sap or resin content.
- They grow slowly and need little maintenance.
- They are short and grow close to the ground.
Additional tips to follow when planning a Fire Wise landscape include:
- Landscape according to the recommended defensible space zones. Plants nearest your home should be more widely spaced and smaller than those farther away.
- Plant in small, irregular clusters and islands, not in large masses.
- Break up the continuity of the vegetation (fuel) with decorative rock, gravel, and stepping stone pathways. This will help modify fire behavior and slow its spread across your property.
- In the event of drought and water rationing, prioritize the plants you wish to save. Provide supplemental water to those nearest your home.
- The homes landscape and the plants in it must be maintained to retain their FIREWISE properties.
An extensive list of FIREWISE plants for New Mexico can be found here: FIREWISE Plant List for New Mexico