SFPUC 2001 Alameda Watershed Management Plan

III. ENVIRONMENTAL SETTING AND IMPACTSG. FIRE MANAGEMENT20 percent slope, one-quarter has a greater than 40 percent slope, approximately 18 percent has a10-20 percent slope, and approximately 14 percent of the land is flat. The topographical featuresof the Watershed include the Calaveras rift valley (which trends northwest through the length ofthe Watershed), a major east-west valley (the La Costa Valley and San Antonio Creek Valley),“V”-shaped canyons formed by Watershed tributaries, and rugged terrain elsewhere. Suchrugged terrain mixed with steeply sloped topography can present firefighting problems andincrease fire intensity due to microclimates.In addition to the characteristics described above, weather is a physical variable that must beconsidered in the analysis of fire behavior. Weather conditions can influence the ignitionpotential of a fire as well as the intensity, rate, and direction of movement. Wind, temperature,and humidity are the more important weather variables used to predict fire behavior. Inparticular, wind conditions can affect the intensity of a fire by supplying oxygen to thecombustion process. Wind can also accelerate the movement of the fire front by angling flamesand transporting embers. In general, winds in the Bay Area blow from the west in the summerand southwest in the winter. Small-scale, terrain controlled winds can be expected atpronounced canyons such as Williams Gulch and the Arroyo Hondo drainage.The Watershed has warm, dry summers and cool, moist winters. Most measurable rainfall occursfrom mid-October to mid-April. May to October is the fire season, and July is the time of highestfire danger. The dry season is approximately 150 days per year, during which an average of 15days are considered to be extreme fire weather conditions.Fire Protection SystemThe physical properties of an area and the fire protection infrastructure available (equipment,personnel training, etc.) are important elements in determining the capacity of fire servicepersonnel to protect the resources at risk. Site characteristics (such as slope steepness) andinfrastructure (such as fire roads and trails) contribute to accessibility by firefighters, andconsequently are also an important part of fire hazard analysis. Fire defense improvementsinclude fuelbreaks, roads, water sources, gates, and helispots (or heliports) that can aid in theeffectiveness of fire suppression. All areas within the Watershed that appear to have other fireprotection problems, either due to equipment/accessibility constraints or significant danger to fireservice personnel, deserve special consideration.Access to the Watershed for fire suppression efforts is provided by I-680, SR 84, as well as byfour major county roads: Calaveras Road (Sunol Valley to Milpitas), Marsh Road (private landseast and southeast of the Watershed), Weller Road (private lands and communication facilitiesnear Monument Peak and Mt. Allison), and Welsh Creek Road (Calaveras Road to privateparcels north of Arroyo Hondo). In addition, numerous gravel/dirt roads and side roads provideaccess to parts of the Watershed.Developed water sources for fire suppression on the Watershed are limited. There are ninehydrants on the Watershed, all located on the valley floors. There are seven water tanks on theNOP 96.223E: Alameda Watershed Management Plan III.G-6 ESA / 930385January 2001