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Eugene -Springfield Area Natural Hazards Mitigation Plan <br />6. Appendices <br />The probability of catastrophic failure of these dams is impossible to estimate with any <br />accuracy, from present data. The Army Corps of Engineers indicates that Lane <br />County's Dams all meet seismic standards and flood standards and that the probability <br />of a dam failure is low, meaning that one incident is likely in a 75 to 100 year period. <br />The 2020 NHMP Steering Committees agree with this assessment. <br />H.4.3 Vulnerability Assessment <br />Eugene and Springfield are both highly vulnerable to inundation from a flood should <br />one of the dam's collapse. Both the Eugene and Springfield steering committees' rate <br />both cities as highly vulnerable to flooding events caused by dam failure, meaning that <br />more than 10% of the population or regional assets could be affected. <br />HAA Risk Analysis <br />Detailed loss estimates for possible failures of these dams are beyond the scope of this <br />mitigation plan. Detailed damage and casualty estimates have not been made for <br />catastrophic dam failures affecting Lane County. However, given the large inundation <br />areas, high water depths, and the logistical difficulties for evacuation, it is not difficult <br />to imagine that a truly catastrophic dam failure could potentially result in loss of life <br />and significant economic impact. <br />H.4.6 Existing Mitigation Activities <br />The Army Corps of Engineers and Eugene Water & Electric Board conducts annual <br />inspections of all dams that it owns, has completed Emergency Action Plans for all <br />dams should they fail, and completes thorough evaluations of each dam every five <br />years. All these actions help to significantly reduce the probability that a dam will fail. <br />The following tables (Table H-4 and H-5) detail significant historic dam and levee <br />failures. <br />6-136 January 2020 <br />