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2025 Hazard Mitigation Plan <br />Kittitas Gounty, Washington <br />Moderate <br />(3) <br />Based on risk drivers, implement interim risk reduction <br />measures as appropriate. Verify risk information is current and <br />implement routine monitoring program; assure O&M is up to <br />date; communicate risk characteristics to the community in a <br />timely manner; verify emergency plans and flood inundation <br />maps are current; ensure community is aware of flood warning <br />and evacuation procedures; and recommend purchase of flood <br />insurance. Support risk reduction actions as a prioritv. <br />Likelihood of inundation due to <br />breach and/or system component <br />malfunction in combination with <br />loss of life, economic, or <br />environmental consequences <br />results in moderate risk. <br />Low <br />(4) <br />Verify risk information is current and implement routine <br />monitoring program and interim risk reduction measures if <br />appropriate; assure O&M is up to date; communicate risk <br />characteristics to the community as appropriate; verify <br />emergency plans and flood inundation maps are current; <br />ensure community is aware of flood warning and evacuation <br />procedures; and recommend purchase of flood insurance. <br />Support risk reduction actions to further reduce risk to as low as <br />practicable. <br />Likelihood of inundation due to <br />breach and/or system component <br />malfunction in combination with <br />loss of life, economic, or <br />environmental consequences <br />results in low risk. <br />Continue to implement routine levee monitoring program, <br />including operation and maintenance, inspections, and <br />monitoring of risk. Communicate risk characteristics to the <br />community as appropriate; verify emergency plans and flood <br />inundation maps are current; ensure community is aware of <br />flood warning and evacuation procedures; and recommend <br />purchase of flood insurance. <br />Likelihood of inundation due to <br />breach and/or system component <br />malfunction in combination with <br />loss of life, economic, or <br />environmental consequences <br />results in very low risk. <br />Very <br />Low <br />(5) <br />No <br />Verdict Not enough information is available to assign an LSAC <br />*Levee risk is the risk that exists due to the presence of the levee sysfem, and this is the risk used to inform the decision on the LSAC <br />assignment. <br />The information presented in this table does not reflect the overTopping without breach risk associated with the presence or operation of the <br />levee svstem. <br />Actions for Levee Systems and Leveed <br />Areas in this Class Risk Characteristics <br />of this ClassRisk <br />leveeactions to <br />Dam and levee failure may occur with little or no warning time. For a dam failure, warning time varies <br />depending on the cause of the failure. For example, in the event of extreme precipitation or massive <br />snowmelt, evacuations can be planned with sufficient time. On the other hand, in the event of a structural <br />failure due to earthquake, there may be no warning time. A dam's structural type also affects warning <br />time. Earthen dams tend to not fail completely or instantaneously, the time of breach formation ranges <br />from a few minutes to a few hours. Once a breach is initiated, discharging water erodes the breach until <br />either the reservoir water is depleted, or the breach resists further erosion. Concrete gravity dams also <br />tend to have a partial breach as one or more monolith sections are forced apart by escaping water. <br />Kittitas County and its planning partners have established protocols for flood warning and response to <br />imminent dam failure in the flood warning portion of adopted emergency operations plans. These <br />protocols are tied to EAPs created by the dam owners. Not all dams have EAPs; only those rated as high <br />hazard are mandated to do so by state and federal regulations. <br />Warning time for levee failures also depends on the cause of the failure. A levee failure caused by <br />structural failure can be sudden and occur with little to no warning. lf heavy rains are impacting a levee <br />system, communities located in the immediate danger zone can be evacuated before a failure occurs. lf <br />the levee failure is caused by overtopping, the community may or may not be able to recognize the <br />impending failure and evacuate. lf a levee failure occurs suddenly, evacuation may not be possible. <br />Chapter 4: Hazard ldentification and Risk Assessment 91