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2021 Multijurisdictional Local Hazard Mitigation Plan 8.3.3 Environment The environment would be exposed to a number of risks in the event of dam failure. The inundation could introduce many foreign elements into local waterways, possibly destroying downstream habitat and exerting detrimental effects on many species of animals. 8.4 VULNERABILITY The vulnerability of people, property, and critical facilities was evaluated for the mapped dam failure inundation area. Detailed results by jurisdiction are included in Appendix E; countywide summaries are provided below. 8.4.1 Population Vulnerable populations are all populations downstream from dam failures that are incapable of escaping the area before floodwaters arrive. Impacts on persons and households for the combined dam failure inundation area were estimated through the Level 2 Hazus analysis. This population includes categories identified for the SoVI rating (see Section 7.2.2), as detailed by jurisdiction in Appendix E and summarized for the overall planning area in Table 8-4. Table 8-4. Distribution of Population Exposed to Dam Failure Hazard by SoVI Rating SoVI Rating Population Living in Exposed Areas Having the SoVI Rating Shown Number of People % of Total Exposed Population Very High 12,222 10.8% Relatively High 29,701 26.2% Relatively Moderate 40,010 35.4% Relatively Low 24,952 22% Very Low 6,301 5.6% Additional countywide results of the Hazus analysis are as follows:  Number of displaced households = 93,665  Number of persons requiring short-term shelter = 7,209 8.4.2 Property Vulnerable properties are those closest to the dam failure inundation zone. These properties would experience the largest, most destructive surge of water. Low-lying areas are also vulnerable since they are where the dam waters would collect. Properties in the dam failure inundation zone that are built to National Flood Insurance Program minimum construction standards may have some level of protection against dam failure inundation, depending on the velocity and elevation of the inundation waters. These properties also are more likely to have flood insurance. Table 8-5 summarizes the loss estimates for dam failure. 8.4.3 Critical Facilities Hazus estimated damage to critical facilities in the dam failure inundation zones as summarized in Figure 8-5. 8-10