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- 4.8.1 Wildfire Risk in Valley County
- Table 59: Wildfire Hazard Risk Assessment
- 4.8.2 Wildfire History in Valley County
- Table 60: Wildfire Data from National Centers for Environmental Information for 1/1/1964 to 1/1/2015
- 4.8.3 Presidential Declared Disasters forWildfires
- Figure 21: WUI for Montana
- 4.8.6 Fire and Climate Change
- 4.8.7 Relationship to Other Hazards
4.8 WildfireWildfires were identified and included in the prior and current hazard mitigation plan for Valley County. An analysis is included in this plan update to include a more in-depth look at what wildfires are, the history of wildfires, and the potential they have to impact county residents. A wildfire is an uncontrolled fire spreading through vegetative fuels, exposing and possibly consuming structures. Wildfires often begin unnoticed, spread quickly, and are usually signaled by dense smoke that may fill the area for miles around. Wildfires can be human-caused through acts such as arson or campfires, or can be caused by natural events such as lightning. Wildfires can be categorized into four types. The first type is wildfires, which are fueled primarily by natural vegetation in grasslands, brushlands, and forests. The second types are extreme fire behavior, which occurs during extreme weather (e.g., high temperatures, low humidity, and high winds) with such intensity that fire suppression is virtually impossible. These events typically burn until the conditions change or the fuel is exhausted. The third types are interface or intermix fires, which occur in areas where both vegetation and structures provide fuel. The fourth and final type are prescribed fires and prescribed natural fires which are intentionally set or natural fires that are allowed to burn for beneficial purposes. 4.8.1 Wildfire Risk in Valley CountyThe overall probability that wildfires will occur each year in Valley County is highly likely and its relative impact is moderate and thus the overall risk for Valley County is moderate. The risk for wildfire for each of the cities is different based on the data available by individual city. In assessing wildfire data for the 2015 update, data from 2009 to 2014 was used to determine the risk. The table below provides the name of each of the cities in the county, the probability that wildfires will have an impact on that jurisdiction, the impact potential, as well as the overall risk calculated by the determined probability and impact ratings. Most notable are Glasgow, Fort Peck, and Nashua, as well as the unincorporated areas of Valley County. Table 59: Wildfire Hazard Risk Assessment
The 2015 update utilized the Risk =Frequency x Consequence (R = FC) formula and each jurisdiction has its own unique risk score based on the 28 points of data analyzed. The risk determined for the 2015 update represents a change from the previous plan. This update indicated the overall risk for Valley County is moderate. Whereas the last plan update completed in 2008 indicated that wildfire posed a high risk for Valley County. 4.8.2 Wildfire History in Valley CountyValley County has a long history of small and large wildfires which have caused no to minimal to severe damages. The extent of damages often depends on the fire spread rate, the effectiveness of suppressionand mitigation measures, and the property and infrastructure in the fire’s path. The history of wildfires can be difficult to compile because of the various firefighting entities involved and a variety of recordkeeping measures utilized over the years. The Valley County Emergency Operations Plan, Wildfire Annex, estimates close to 200 fire starts occur annually in the county. The table below outlines the historical wildfires which have taken place in Valley County from the National Centers for Environmental Information. Since 2003, there have been six major wildfireincidents reported for Valley County. The most recent wildfire was reported in 2010 which produced $75,000 in property damage. Table 60: Wildfire Data from National Centers for Environmental Information for 1/1/1964 to 1/1/2015
4.8.3 Presidential Declared Disasters forWildfiresThere have been numerous statewide declared disasters related to wildfires in Montana, however, none which has been specific to Valley County in the last five years. 4.8.4 Mitigation Actions in the Past Five YearsWildfire remains a high priority in this iteration of the mitigation plan. Education, surveillance, and prevention projects identified in the previous plan will remain. A focus in this iteration of the plan is to improve capacities such as the speed of response and the area served. 4.8.5 VulnerabilityTopography and weather are factors that contribute significantly to wildfire behavior: Topography is related to slope of land. As slope increases the rate of wildfire spread increases. South facing slopes are also subject to greater solar radiation, making them drier and thereby intensifying wildfire behavior. Ridge tops may mark the end of wildfire spread, since fire spreads more slowly or may even be unable to spread downhill. Weather is also one of the most important variable factors affecting wildfire behavior. Important weather variables are temperature, humidity, the wind, and lightning. Weather events ranging in scale from localized thunderstorms to large fronts can have major effects on wildfire occurrence and behavior. Extreme weather, such as high temperatures and low humidity, can lead to extreme wildfire activity. By contrast, cooling and higher humidity often signal reduced wildfire occurrence and easier containment. Structures in jurisdictions that mix with forests, peat bogs, and prairies are vulnerable to damages to wildfires. According to the 2013 State of Montana Multi-Hazard Mitigation Plan, increased population growth over the past two decades in Montana has resulted in an expanded Wildland Urban Interface (WUI). Fires in these WUI areas have become much larger and burned with greater intensity. A Communities At-Risk Analysis was completed across the state, identifying fire risk factors immediately around Montana communities (Dannenberg, 2004). Data was collected on vegetation, slope, aspect, weather factors, development density, and building materials within a 5-mile radius of 622 towns and cities in Montana. The results of the BLM communities risk assessment showed that 213 of the 622 communities in Montana (34%) were rated with an extreme or high fire danger rating. As residential areas expand into relatively untouched forest land, people living in the WUI are increasingly threatened by forest fires. An estimated 360,000 people live in homes in the WUI in the Northern Rockies that are directly vulnerable to wildfire. The value of their homes is estimated at $21 billion. Fires in WUI areas pose anextreme risk to human life and property, increase the cost of fire suppression activities, endanger the lives of firefighters, and have significant social, economic, and natural resources impacts. Montana Department of Natural Resources and Conservation (DNRC) fire report data shows that through the direct protection program, 50 percent more fires occurred in WUI than non-WUI areas between 1996 and 2006. Within the WUI areas, 64 percent of the fires were human-caused, with the majority of the causes being campfires and debris burning. Outside the WUI, only 27 percent of the fires were human-caused. The following figure depicts the Wildland Urban Interface (WUI) in Montana as compiled from completed Community Wildfire Protection Plans as consolidated by Montana DNRC. Figure 21: WUI for Montana
The wildland-urban interface is a very popular place to live in Montana. Development in the hazard areas has increased in recent years and has amplified the vulnerabilities in the unincorporated parts of the State. Regulating growth in these areas is a delicate balance between protecting private property rights and promoting public safety. Some counties have growth policies recognizing the wildfire threat and emphasizing defensible space, inspection of new development, water supplies, fuels mapping, and Firewise programs. The2008 Valley County Pre-Disaster Mitigation Plan indicated problems with wildfire occur when combined with the human environment. People, structures, property, rangelands, and croplands near wildfires can be threatened unless adequately protected through evacuation, mitigation, or suppression. The Wildland-Urban Interface (WUI) is defined as the zone where structures and other human development meet or intermingle with undeveloped wildland or vegetative fuel. In northeast Montana, the WUI typically is where the edge of local communities adjoin agricultural and non‐irrigated fields. Specifically, those Valley County communities designated as “Communities at Risk” in the Federal Register include: ▪ Baylor ▪ Fort Peck ▪ Glasgow ▪ Glentana ▪ Hinsdale ▪ Nashua ▪ Opheim ▪ Richland ▪ Tampico ▪ Theony ▪ Vandalia Source: US Bureau of Land Management, 2004
Major factors in the increased frequency and severity of fires include significantly earlier snowmelt and hotter summer temperatures and associated reduced soil moisture. The longer fire season and the expanded vulnerable areas of high-elevation forests are combing to produce the increase in frequency and severity of wildfires. 4.8.7 Relationship to Other HazardsWildfires and structural fires are associated with other hazards such as summer storms, drought, flood, and winter storms. As a natural hazard, a wildfire is often the direct result of a lightning strike that may destroy personal property and public land areas, especially on thestate and national forest lands. Drought is an associated hazard because drought conditions cause high temperatures and dry conditions, which can increase the risk of fires. Summer storms are related because lighting strikes may ignite a structural fire. Windstorms that damage structures can cause a fire direct or result inan increase the fuel load for a wildfire increasing the risk of a structural fire. Flood, tornado, and high winds may also cause structural fires in their aftermath. Downed power lines, natural gas leaks or other sources of ignition initiated by natural hazards may spark afire in structures. Routes to structures may be restricted due to flooding or debris from storms. Winter storms, such as blizzards or ice storms, may impair the movement of response vehicles and decrease response time to structural fires. The reduced response time could potentially increase the amount of damage. Download 4.32 Mb. Share with your friends:
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