Alpine County Draft Wildfire Risk Mitigation Plan December 2020 Alpine County Draft Wildfire Risk Mitigation Plan December 2020 Prepared for: Alpine County Community Development Department 50 Diamond Valley Road Markleeville, CA 96120 530-694-1371 [email protected] Prepared by: Scott Conway; Jason Moghaddas, RPF Spatial Informatics Group 2529 Yolanda Ct. Pleasanton, CA 94566 Tania Treis Panorama Environmental, Inc. 717 Market Street, Suite 650 San Francisco, CA 94103 650-373-1200 Cover Photo Credit: (Monti, 2020; Paulus, 2020) www.panoramaenv.com TABLE OF CONTENTS Table of Contents Acronyms and Abbreviations ..................................................................................................................................... v 1 Introduction ......................................................................................................................................................... 1 1.1 Background ..................................................................................................................................................... 1-1 1.2 Goals and Objectives ..................................................................................................................................... 1-2 1.3 Scope of Wildfire Risk Mitigation Plan ...................................................................................................... 1-2 1.4 Existing Fuel Management Planning, Projects, and Regional Capabilities ........................................ 1-4 1.5 Plan Development Process .......................................................................................................................... 1-6 2 Technical Analyses ....................................................................................................................................... 2-1 2.1 Key Terms ........................................................................................................................................................ 2-1 2.2 Introduction ..................................................................................................................................................... 2-1 2.3 Fire Hazard Analysis ...................................................................................................................................... 2-2 2.4 Susceptibility Analysis – HVRA Analysis ................................................................................................ 2-29 2.5 Wildfire Risk Assessment ........................................................................................................................... 2-36 3 Wildfire Risk Mitigation Projects .............................................................................................................. 3-1 3.1 Development and Prioritization of Potential Projects ............................................................................. 3-1 3.2 Projects Included in the WRMP by Tier .................................................................................................... 3-2 3.3 Environmental Review Considerations for Risk Mitigation Projects ................................................. 3-20 4 Implementation Plan ..................................................................................................................................... 4-1 4.1 Methods and Tools ........................................................................................................................................ 4-1 4.2 Project 1: Markleevillage .............................................................................................................................. 4-6 4.3 Project 2: Manzanita ...................................................................................................................................... 4-6 4.4 Project 3: Bear Valley .................................................................................................................................... 4-7 4.5 Environmental Considerations and Review .............................................................................................. 4-8 4.6 Estimated Cost and Funding Sources ........................................................................................................ 4-1 4.7 Implementation of Other Projects Identified in the WRMP ................................................................... 4-6 5 Community Access Risk Assessment ....................................................................................................... 5-1 5.1 Ingress/Egress and Community Evacuation Area Identification .......................................................... 5-1 5.2 Community Access Risk Report .................................................................................................................. 5-5 Alpine County ●Draft Wildfire Risk Mitigation Plan ● December 2020 i TABLE OF CONTENTS 6 References ...................................................................................................................................................... 6-1 List of Tables Table ES-0-1 HVRA Accounting for Alpine County ........................................................................................... 6 Table ES-0-2 Typical Vegetation Treatments................................................................................................... 10 Table 2-1 Aspect Data for Alpine County by Percent ............................................................................ 2-6 Table 2-2 Elevation Data for Alpine County by Percent ......................................................................... 2-7 Table 2-3 Slope Data for Alpine County by Percent ............................................................................... 2-8 Table 2-4 Land Cover Types within Alpine County Planning Areas .................................................. 2-10 Table 2-5 Vegetation Condition Class Definitions ................................................................................. 2-12 Table 2-6 Fuel Model Type by Percent ................................................................................................... 2-14 Table 2-7 Stand Heights by Percent ........................................................................................................ 2-15 Table 2-8 Canopy Cover by Percent ........................................................................................................ 2-16 Table 2-9 Canopy Bulk Density by Percent ............................................................................................ 2-17 Table 2-10 Canopy Base Height by Percent ............................................................................................ 2-18 Table 2-11 Spatial Distribution of Flame Length Classes ...................................................................... 2-24 Table 2-12 Percent of Each Classification of Integrated Hazard ......................................................... 2-27 Table 2-13 HVRA Accounting for Alpine County ..................................................................................... 2-31 Table 2-14 Results of Surveys Determining Response to Wildfire ...................................................... 2-34 Table 2-15 Results of Surveys Determining Relative Importance ....................................................... 2-35 Table 2-16 Additional Filter by Slope ......................................................................................................... 2-38 Table 2-17 Additional Filter by Land Ownership ...................................................................................... 2-38 Table 2-18 Areas of Risk and Acres of Opportunity by Land Management or Ownership ............. 2-50 Table 3-1 Projects Included in the Wildfire Risk Mitigation Plan by Tier........................................... 3-4 Table 3-2 Options for Project Environmental Review under CEQA ................................................... 3-20 Table 4-1 Personnel Needed to Implement Treatment Methods ........................................................ 4-5 Table 4-2 Potential Special Status Species Found in Alpine County .................................................. 4-1 Table 4-3 Estimates of Cost by Treatment Types .................................................................................... 4-1 Table 4-4 Potential Grant Opportunities for Fuel Management Projects ........................................... 4-3 Table 4-5 Development of Future Projects ............................................................................................... 4-7 Table 4-6 Outreach Actions and Timing ................................................................................................... 4-9 Table 5-1 Safety Zone Rules for Safe Separation Distances .............................................................. 5-4 Table 5-2 Acreages of the Highest 50th Percentile Risk around Ingress and Egress Routes ........ 5-5 List of Figures Figure 1-1 Land Ownership and Communities in Alpine County ........................................................... 1-3 Figure 1-2 Summary of WRMP Development Process ........................................................................... 1-6 Figure 2-1 Components of Wildfire Risk Analysis .................................................................................... 2-2 Figure 2-2 Fire Behavior Modeling Workflow ..........................................................................................