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City of Pleasanton 2023-2031 (6th Cycle) Housing Element Update Errata Final EIR 3-28 FirstCarbon Solutions https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480022/EIR/4 - Final EIR/21480022 Sec03-00 Errata.docx Model and/or other methodologies acceptable to the City), and reduce VMT impacts to less than the applicable VMT thresholds. Section 3.15—Utilities and Service Systems Page 3.15-2, Fifth Full Paragraph In response to ZONE 7-7, the following paragraph has been revised: Potable Water Source and Supply Purchased Surface Water Zone 7 currently derives approximately 80 90 percent of its water supply from the State Water Project, with water from the South Bay Aqueduct, surface runoff collected in the Del Valle Reservoir, with local groundwater representing the remaining supply (20 percent). The remaining 10 percent is local rainfall captured in Lake Del Valle. Water delivered to Pleasanton comes primarily from the State Water Project. The 2020 UWMP concluded that Zone 7 can supply 100 percent of water demand in all conditions, including drought, up to the 2045 projections as shown in Table 3.15-2. Zone 7 is also engaging in future water supply projects, including the Bay Area Regional Desalination Project, Delta Conveyance Project, Potable Water Reuse, and the Proposed Sites Reservoir. These projects are projected to provide a cumulative additional water supply of over 1,500,000 acre-feet per year (AFY) (Appendix H).4 Page 3.15-4, Before Third Full Paragraph In response to ZONE 7-2, the following paragraph has been added: Per- and Polyfluoroalkyl Substances It has since been determined that all groundwater supply wells for the city may be taken out of commission no later than the first quarter of 2023. Currently, groundwater makes up approximately 20 percent of the total water supply for the City, and, if the existing groundwater supply wells are taken out of commission, this 20 percent will not be available to the City without treatment or additional supply sources. As noted, the City is evaluating options to replace or restore this supply. 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 to be taken offline because they can no longer meet the PFHxS response levels without treatment and blending capability. Zone 7 is currently developing PFAS treatment facilities for two affected well fields and will continue to develop plans for meeting groundwater production needs as PFAS regulations evolve. Zone 7 expects to be able to meet the City’s increased demands in the short-term, and Zone 7 will continue to work with the City to evaluate this alternative as a long-term option. 4 Watearth. 2022. City of Pleasanton Water Supply Assessment (WSA) for 2023-2031 Housing Element Update. October.