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1839662v3 Page 2 broader groundwater supply context. Specifically, it should be noted that PFAS contamination also adversely affects Zone 7’s groundwater production capacity; most recently, perfluorohexane sulfonic acid (PFHxS) regulations issued in November 2022 have resulted in two of Zone 7’s wells being taken offline as they can no longer meet the PFHxS response levels without treatment and blending capability. Zone 7 is developing PFAS treatment facilities for two affected well fields, and will continue to develop plans for meeting groundwater production needs as PFAS regulations evolve. The DEIR should acknowledge this broader context, which impacts all well operators’ ability to access groundwater supply without additional treatment, and which may require the imposition of treatment systems throughout the supplied area. As the DEIR notes, the City is currently studying alternative water supply sources in lieu of the City’s groundwater production, including receiving additional water supply from Zone 7. While Zone 7 expects to meet the City’s increased demands in the short-term, Zone 7 will be working with the City to evaluate this alternative as a long-term option. In summary, the DEIR should adequately describe regional PFAS contamination issues and the City’s efforts to identify potential sources of supply based on the outcome of the City’s current alternative water supply study. Within that context, we offer the following additional comments: x Page 3.15-35, Water Supply and Groundwater Contamination: The DEIR states that if the City’s current wells (which supply 20% of the City’s water) are decommissioned, that 20 percent of supply “will not be available to the City without treatment or additional supply sources.” The DEIR further represents that Zone 7 has not identified any impacts to Zone 7’s water supply for the city as a result of the elevated pollutants of concern in groundwater. While it is true that Zone 7 has not identified impacts on its water supply for the City based on the values presented in the 2020 UWMP, state regulations concerning PFAS continue to evolve, and have the potential to impact Zone 7’s well production just as they have the City’s. Zone 7 will therefore continue to evaluate PFAS impacts on water supplies, and will keep the City apprised of any new developments. x Page 3.15-36, Water Supply and Groundwater Contamination: The DEIR suggests that “[a]lthough Zone 7 has sufficient supplies available,” because the City is still evaluating options for alternative supply, the water supply deficiencies identified in the document are deemed significant for the purposes of CEQA analysis. As indicated elsewhere in these comments, Zone 7 is also evaluating the impacts of PFAs on water supplies, and that analysis is likely to inform its planning into the future. This representation about the sufficiency of Zone 7’s supplies to meet the City’s deficiencies is too general without context or time parameters, and the =RQH 3DJHRI &217