Res 2018-025/adopting the 2018 Hays County, Texas Hazard Mitigation Plan as the official plan of the City; authorizing the inclusion of the City of San Marcos Hazard Mitigation Plan as an appendix; designating the City Manager as the official authorized

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Dam/Levee Failure Dam/Levee Failure: Description According to the 2013 State of Texas Hazard Mitigation Plan Update, a dam failure is defined as a systematic failure of the dam structure resulting in the uncontrolled release of water, often resulting in floods that could exceed the 100-year floodplain boundaries. The US Army Corps of Engineers (USACE) defines levees as an earthen embankment, floodwall, or structure along a water course whose purpose is flood risk reduction or water conveyance. Dam/Levee Failure: Extent Scale Risk Assessment The extent of dam failures can be measured in terms of depth of flooding within the inundation area. Additionally, it can measured in terms of loss of life, economic impact, and volume of water overtopping into the inundation areas. The Texas Commission on Environmental Quality (TCEQ) provides metrics that classify dams based on this criteria, as seen on Tables 2.28 and 2.29. Human and Economic Impact No loss of life expected (no lives or permanent habitable structures in the inundation area); Low Minimal economic loss (failure may cause damage to occasional farms, agricultural improvements, and minor highways). Loss of life is possible (1 to 6 lives or 1 to 2 permanent habitable structures in the inundation area); Significant Appreciable economic loss (failure may cause damage to isolated homes, secondary highways, minor railroads, or cause interruption of public services). Loss of life is expected (7 or more lives or 3 or more permanent habitable structures in the inundation area); High Excessive economic loss (failure may cause damage to public, agricultural, industrial, or commercial facilities or utilities, and main highways or railroads.) Size Impoundment Maximum Storage (Ac-ft)Height (ft) At Least 15 & Less Than 1,000At Least 25 & Less Than 40 Small At Least 50 & Less Than 1,000At Least 6 & Less Than 40 IntermediateAt Least 1,000 & Less Than 50,000At Least 40 & Less Than 100 LargeAt Least 50,000At Least 100 Jurisdiction-specific data for location, previous occurrences, extent, probability, impact, and vulnerability are found in jurisdiction annexes. 57