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flooding and beach loss, and mobilization of subsurface contaminants. <br />Sea level rise will increase the exposure of communities, assets, services <br />and culturally important areas to significant impacts from coastal storms. <br />• Sea level rise will increase the frequency of coastal flooding events, <br />which occur when sea level rise amplifies short-term elevated water <br />levels associated with higher tides, large storms, El Niño events, or when <br />large waves coincide with high tides. California communities need to be <br />aware of and prepared for a likely rapid increase in the frequency of <br />coastal flooding in the next decade, even beyond the increases in coastal <br />flood frequency already occurring. <br />• Groundwater rise poses a threat to below-ground infrastructure and <br />freshwater aquifers under future sea level scenarios. In areas with <br />shallow unconfined groundwater, the water table will generally rise with <br />sea level, depending on local geomorphology. Rising groundwater may <br />mobilize subsurface contaminants in soils, expose underground <br />infrastructure to corrosive saltwater, and put freshwater aquifers at risk <br />of saltwater Intrusion. <br />2. <br />The Department of Toxic Substance Control (DTSC) adopted its Guidance <br />document on On October 2, 2024, to include its SLR Action Plan with the <br />following statement: <br />“Best available science, such as the State Sea Level Rise Guidance, <br />should be consulted to determine which scientifically based sea level rise <br />scenarios are most appropriate. <br />Different targets will likely be needed for vulnerability assessments and <br />adaptation <br />strategies associated with coastal ecosystems in order to assess how <br />these areas and <br />associated nature-based solutions might keep pace with rising sea levels. <br />Critical infrastructure (highways, bridges, water treatment plants, etc.) <br />should consider higher SLR scenarios, as appropriate, based on State <br />Guidance. New and <br />re-development in the coastal zone should utilize these targets as <br />consistent minimum <br />criteria for planning for the impacts of SLR. <br />“...SLR has the potential to significantly impact waste at a site by causing <br />groundwater levels to rise, by inundation, and by the subsequent <br />deterioration of the remedy and mobilization of contaminants. SLR can <br />also impede stormwater drainage, damage critical infrastructure, and <br />exacerbate erosion, all of which could negatively impact cleanup efforts <br />while increasing the cleanup complexity at the site.”