Riverside Fire Erosion Threat Assessment/Reduction Team (ETART) Extended Report December 2020 ETART Extended Report – Riverside Fire This page intentionally left blank. DR-4562-OR | EROSION THREAT ASSESSMENT/REDUCTION TEAM ETART Extended Report – Riverside Fire Table of Contents Executive Summary ................................................................................................................... 1 1. Overview .................................................................................................................................. 3 1.1. Burned Area Characterization ........................................................................................ 3 1.2. Post-fire Watershed Condition ........................................................................................ 8 Risk Assessment and Recommendations .............................................................................. 13 1. Human Life and Safety Summary ........................................................................................ 13 1.1. Hazard Trees ................................................................................................................. 13 1.2. Debris flow, Rock fall, and Landslides ........................................................................ 14 1.3. Post-Fire Flooding, Floating Debris, and Others ......................................................... 15 2. Property Summary ................................................................................................................ 16 3. Natural Resources Summary ............................................................................................... 20 3.1. Soil and Water .............................................................................................................. 20 3.2. Fish and Wildlife Habitat .............................................................................................. 20 3.3. Native Plant Communities Summary .......................................................................... 24 3.4. Cultural Resources Summary ...................................................................................... 28 4. Monitoring and Management Recommendations ............................................................... 29 4.1. Watershed Response and Hydrologic Analysis - Monitoring Recommendations ..... 30 4.2. Geologic Hazards - Management Recommendations................................................ 30 4.3. Roads and Travel Routes - Management Recommendations ................................... 31 4.4. Fish/Aquatic Habitat - Management Recommendations and Monitoring ................ 31 Resource Reports.................................................................................................................... 32 1. Weeds Specialist Report ...................................................................................................... 32 2. Engineering Report ............................................................................................................... 55 2.1. Objectives ..................................................................................................................... 55 2.2. Values at Risk ............................................................................................................... 55 2.3. Observations ................................................................................................................. 56 2.4. Reconnaissance Methodology and Results ................................................................ 56 DR-4562-OR – December 2020 i ETART Extended Report – Riverside Fire 2.5. Findings ......................................................................................................................... 57 2.6. Recommendations ....................................................................................................... 57 2.7. Management Recommendations ................................................................................ 58 2.8. References .................................................................................................................... 58 3. Heritage and Cultural Resources ......................................................................................... 59 3.1. Setting ........................................................................................................................... 59 3.2. Background ................................................................................................................... 60 3.3. Critical Values and Proposed Treatments .................................................................. 62 3.4. Assessment Methodology ............................................................................................ 62 4. Soil Resources ...................................................................................................................... 64 4.1. Summary ....................................................................................................................... 64 4.2. Resource Condition and Setting .................................................................................. 65 4.3. Assessment Methodology ............................................................................................ 67 4.4. Findings ......................................................................................................................... 68 4.5. Recommendations ....................................................................................................... 70 5. Hydrology Resources ............................................................................................................ 73 5.1. Objectives ..................................................................................................................... 73 5.2. Critical Values ............................................................................................................... 73 5.3. Resource Condition and Setting .................................................................................. 74 5.4. Assessment Methodology and Modeling .................................................................... 79 5.5. Findings ......................................................................................................................... 79 5.6. Recommendations ....................................................................................................... 82 5.7. References .................................................................................................................... 83 6. Geologic Hazards ................................................................................................................. 84 6.1. Introduction .................................................................................................................. 84 6.2. Assessment Methodology ............................................................................................ 86 6.3. Findings ......................................................................................................................... 87 6.4. Recommendations ....................................................................................................... 88 6.5. Mitigation and Further Evaluation ............................................................................... 90 6.6. References .................................................................................................................... 91 DR-4562-OR – December 2020 ii ETART Extended Report – Riverside Fire 7. Hazard Trees ........................................................................................................................ 94 7.1. Objectives ..................................................................................................................... 94 7.2. Danger/Hazard Trees Described ................................................................................. 94 7.3. Recommendations ....................................................................................................... 98 7.4. Danger Tree Guidelines ............................................................................................. 101 7.5. References .................................................................................................................. 108 8. Fish and Wildlife Resources ............................................................................................... 111 8.1. Objectives ................................................................................................................... 111 8.2. Assessment Methodology - Field and Modeling ....................................................... 111 8.3. Resource Setting ........................................................................................................ 111 8.4. Critical Values, Results, Risk Assessment, and Recommendations ....................... 111 8.5. Recommended Monitoring ........................................................................................ 112 Riverside ETART Members .................................................................................................... 113 Appendix A – Road Treatment Cost Estimates ..................................................................... 115 Appendix B – Supporting Botany Information ...................................................................... 117 Appendix C – Supporting Soil Information ...........................................................................