The RCI Project Team, composed of experts in the fields of fire behavior and suppression, geographic information systems (GIS), and forest and rangeland ecology, collaborated to complete a Community Risk/Hazard Assessment for each of the identified communities in Lincoln County. The RCI Field Teams included a Fire Specialist with extensive working wildland fire experience in Nevada, and a Resource Specialist experienced in the natural resource environments in Nevada.
The RCI Project Team used standardized procedures developed from the Draft Community Wildland Fire Assessment For Existing and Planned Wildland Residential Interface Developments in Nevada (Nevada’s Wildland Fire Agencies, Board of Fire Directors, April 2001; revised 2002). This approach incorporates values for hazardous fuels and landscape features, hazardous structural features, community design, and fire protection capabilities into an overall community rating. A glossary of wildland fire terms frequently used in describing assessment results and recommendations is included in Appendix A.
Geographic Information System (GIS) Specialists on the RCI Project Team compiled and reviewed existing statewide geospatial data to create maps for recording baseline data and data verification in the field. Data sources for the maps were the Nevada Fire Safe Council, the Nevada Department of Transportation, the US Forest Service, and the Bureau of Land Management. Datasets and sources utilized are summarized in Table 2-1.
Spatial Dataset | Data Source |
---|---|
Land Ownership | BLM Nevada State Office Mapping Services |
Vegetation Communities | Nevada Gap Analysis Program Data, Utah Cooperative Fish and Wildlife Research Unit, Utah State University |
Topography | US Geological Survey Digital Elevation Models and Topographic Maps |
Fire Suppression Resources | Field Interviews |
Roads | “TIGER” Census data 2000 |
Current Aerial Photographs | USGS Digital Orthophoto Quadrangles (1994, 1996, or 1998) |
Fuel Hazard Classes | BLM Nevada and Utah State Office Fire Hazard Potential Data |
Fire History | BLM Nevada State Office Mapping Services USFS Humboldt-Toiyabe Supervisor’s Office National Interagency Fire Center - Boise, Idaho |
Recorded wildfire history was mapped using Bureau of Land Management and US Forest Service datasets and GIS databases that identify wildfire perimeters on federally administered lands during the past 24 years. Fire perimeters were mapped by agency personnel using Global Positioning System (GPS) data and screen digitizing from source maps with a minimum detail level of 1:250,000. The datasets have been updated at the Bureau of Land Management Nevada State Office and Humboldt-Toiyabe Supervisors Office at the end of each fire season from information provided by each BLM Field Office and Humboldt-Toiyabe Ranger District. The datasets are intended to be central sources of historical GIS fire data to support fire management efforts and land use planning on federal lands.
In addition to the fire perimeter information, point data for all recorded fire ignitions within Nevada from 1980 to 2003 was obtained from the National Interagency Fire Center (NIFC) database in Boise, Idaho. This dataset includes an ignition point coordinate and an acreage component as reported to NIFC through a variety of agencies. This data is included in Table 3-2 and provides the ignition point locations for the maps in this report. In many cases, the ignition point location is only accurate within the section; in such cases, the point coordinate is located in the section center on the maps.
The wildfire history and ignition history data were used to formulate risk ratings and to develop recommendations specific to areas that have been repeatedly impacted by wildland fires. Observations made by the RCI Project Team and comments from local fire agency personnel were used to develop recommendations in areas without recent wildfire activity where a significant buildup of fuels or expansion of urban development into the interface area represents a growing risk.
The wildland-urban interface is the place where homes and wildland meet. This project focuses on identifying risks and hazards in the wildland-urban interface areas countywide by assessing each community individually. Site-specific information for each Lincoln County community was collected during field visits conducted between September 13 and 15, 2004. The predominant conditions recorded during these site visits were used as the basis for the community risk and hazard assessment ratings.
The Fire Specialist on the RCI Project Team assigned an ignition risk rating of low, moderate, or high to each community assessed. This rating was based on four sources of information: interpretation of the historical record of ignition patterns and fire polygons provided by the National Interagency Fire Center, Bureau of Land Management, and US Forest Service databases, interviews with local fire department personnel and local Fire Management Officers, field visits to each community, and the professional judgment of the RCI Project Team Fire Specialists based on their experience with wildland fire ignitions in Nevada.
The Community Risk/Hazard Assessments were completed using methodology outlined in the Draft Community Wildland Fire Assessment For Existing and Planned Wildland Residential Interface Developments in Nevada. This system assigns hazard ratings of low through extreme based on the scoring system shown in Table 2-2 and detailed in Appendix B.
Hazard Category | Score |
---|---|
Low Hazard | < 41 |
Moderate Hazard | 41-60 |
High Hazard | 61-75 |
Extreme Hazard | 76+ |
To arrive at a score for the community, five primary factors that affect potential fire hazard were assessed: community design, construction materials, defensible space, availability and capability of fire suppression resources, and physical conditions such as fuel loading and topography. A description of each of these factors and their importance in developing the overall score for the community is provided below. Individual community score sheets presenting the point values assigned to each element in the hazard assessment are provided at the end of each community assessment.
Aspects of community design account for 26 percent of the total assessment score. Many aspects of community design can be modified to improve community fire safety. Factors considered include:
The type of building materials used for construction account for sixteen percent of the total assessment score. While it is not feasible to expect all structures in the wildland-urban interface area to be rebuilt with fire-resistant materials, there are steps that can be taken to address specific elements that strongly affect structure ignition potential in the interface area. Factors considered in the assessment include:
Defensible space accounts for sixteen percent of the assessment score. Density and type of fuel around a home determines the potential fire exposure and potential for damage to the home. A greater volume of trees, shrubs, dry weeds, dry grass, woodpiles, and other combustible materials near the home will ignite more readily, produce more intense heat during a fire, and increase the threat of losing the home. Defensible space is one of the factors that homeowners can most easily manipulate in order to improve the chances that a home or other property avoids damage or complete loss from a wildfire.
The availability and capability of fire suppression resources account for sixteen percent of the total assessment score. Knowledge of the capabilities or limitations of the fire suppression resources in a community can help the residents take action to maximize the resources available. Factors considered in the assessment include:
The physical conditions that influence fire behavior account for 26 percent of the hazard rating. Physical conditions include slope, aspect, topography, fuel type, and fuel density. With the exception of changes to the fuel composition, the physical conditions in and around a community cannot be altered to make the community more fire safe. Therefore, an understanding of how these physical conditions can influence the behavior of a fire is essential to planning effective preparedness activities, such as fuel reduction treatments. Physical conditions considered in the assessment include:
Fuel hazard maps were initially prepared by the BLM (Nevada and Utah State Offices) using wildfire hazard delineations derived from vegetation data (Nevada GAP Analysis Program satellite dataset at 30-meter resolution). A total of 65 vegetation types were mapped statewide and classified into four wildfire hazard categories (low, moderate, high, and extreme) based on the anticipated fire behavior for each vegetation cover type. For example, pinyon-juniper cover types were generally rated as extreme fuel hazards, while sparse shadscale cover types were rated as low fuel hazards.
The RCI Project Teams visited high and extreme hazard communities and verified the BLM fuel hazard information by comparing the hazard ratings on the existing fuel hazard map to vegetation, slope, and aspect conditions directly observed in the field. Where necessary, changes to the ratings were drawn on the maps and used to update the fuel hazard layer of the project database. Photo points were established in high and extreme fuel hazard areas to monitor future changes in fuel hazard conditions. Fuel hazard mapping was completed for the Lincoln County communities of Eagle Valley/Ursine, Mt. Wilson, and Pioche. Photos of representative fuel types in Lincoln County are included in Appendix C.
The Fire Specialists on the RCI Project Team described a worst-case scenario for each community based on an analyses of the severe fire behavior that could occur given a set of weather conditions, observed fuel load conditions, and minimal fire suppression resources. The worst-case scenario does not describe the most likely outcome of a wildfire event in the interface, but it illustrates the potential for damage if a given set of conditions were to occur simultaneously. The worst-case scenarios described in this document are for public education purposes and are part of the basis for the fuel reduction recommendations.
The Fire Specialists on the RCI Project Team interviewed local fire department personnel and local area Fire Management Officers to obtain information on wildfire training, emergency response time, personnel, equipment availability, evacuation plans, pre-attack plans, and estimates of possible worst-case scenarios. Local fire personnel reviewed maps showing the history of wildfires to ensure that local information on wildland fires was added to the dataset when possible. A list of fire agency personnel contacted for information used in the assessments is included in Appendix D.
A wide variety of treatments and alternative measures can be used to reduce ignition risks, mitigate fire hazards, and promote fire safe communities. Proposed recommendations typically include physical removal or reduction of flammable vegetation, increased community awareness of the risk of fires and how to reduce those risks, and coordination among fire suppression agencies to optimize efforts and resources. The RCI Project Team met repeatedly to analyze community risks, treatment alternatives, and treatment benefits. Treatment recommendations to reduce existing risks were formulated based upon professional experience, quantitative risk assessment, and information developed inconjunction with the “Living With Fire” publications, National Fire Plan, and FIREWISE resources (National Fire Plan website: www.fireplan.gov/reports/7-19-en.pdf; FIREWISE website: www.firewise.org; and Nevada Cooperative Extension publications). The recommendations included in this report are considered high priorities for individual communities and are presented in a relative order of importance.