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2025 URBAN WATER MANAGEMENT PLAN <br /> MAY 2026/FINAL DRAFT/CAROLLO <br /> additional contaminants of concern to monitor the safety of its waters (MET, 2025). MET's supplies <br /> originate primarily from the CRA and from the SWP.A blend of these two sources, proportional to each <br /> year's availability of the source, is then delivered throughout MET's service area. <br /> Although the CRA and SWP have different water quality characteristics, MET has implemented effective <br /> treatment and management strategies to maintain high-quality water.The CRA water source contains <br /> higher total dissolved solids (TDS) and the SWP contains higher levels of naturally occurring organic <br /> matter, lending to the formation of disinfection byproducts.To remediate the CRA's high level of salinity <br /> and the SWP's high level of organic matter, MET blends CRA and SWP supplies and has upgraded all its <br /> treatment facilities to include ozone treatment processes. In addition, MET has been engaged in efforts to <br /> protect its Colorado River supplies from threats of uranium, perchlorate, and chromium VI while also <br /> investigating the potential water quality impact of the following emerging contaminants: <br /> N-Nitrosodimethylamine, pharmaceuticals and personal care products, microplastics, per- and <br /> polyfluoroalkyl substances (PFAS), and 1,4-dioxane (MET, 2025). <br /> PFAS is a group of widely used man-made "forever chemicals"that include both perfluorooctanoic acid <br /> (PFOA) and perfluorooctane sulfonate (PFOS). MET has voluntarily monitored PFAS in its source and <br /> treated waters since 2017. Most samples have shown non-detect (ND) for all tested PFAS, including PFOA <br /> and PFOS.A limited number of other PFAS—such as PFHxA, PFBA, PFPeA, PFDoA, PFTA, and PFBS, have <br /> been detected only at trace levels below their method detection limits. PFOA and PFOS have not been <br /> detected in Metropolitan's imported or treated water supplies. Some member agencies, however, have <br /> detected these compounds in local groundwater wells,which may require treatment or source <br /> management to comply with emerging Division of Drinking Water (DDW) regulations.As DDW and <br /> United States (US) Environmental Protection Agency (EPA) establish enforceable maximum contaminant <br /> levels (MCLs) for PFOA and PFOS, some agencies may supplement their local supplies with increased <br /> purchases of MET water (MET, 2025). <br /> The EPA finalized the first national drinking water standards for six PFAS compounds in April 2024.These <br /> standards include enforceable MCLs for PFOA and PFOS set at 4 parts per trillion (ppt). In May 2025, the <br /> EPA announced that it would extend the compliance deadline for PFOA and PFOS from 2029 to 2031 to <br /> provide additional time for testing, planning, and installation of treatment technologies.While MET and <br /> its member agencies continue to monitor and test PFAS in imported and local sources, the delay in the <br /> federal compliance date allows additional time to evaluate treatment options, coordinate funding, and <br /> plan system upgrades necessary to meet forthcoming federal PFAS standards. <br /> The presence of quagga mussels in water sources is a water quality concern. Quagga mussels are an <br /> invasive species that was first discovered in 2007 at Lake Mead on the Colorado River.This species of <br /> mussels forms massive colonies in short periods of time, disrupting ecosystems and blocking water <br /> intakes.They can cause significant disruption and damage to water distribution systems. MET has had <br /> success in controlling the spread and impacts of the quagga mussels within the CRA; however,the future <br /> could require more extensive maintenance and reduced operational flexibility than current operations <br /> allow. It also resulted in MET eliminating deliveries of CRA water into Diamond Valley Lake (DVL) to keep <br /> the reservoir free from quagga mussels (MET, 2025). <br /> In addition, golden mussels, another invasive species capable of disrupting pipelines and altering <br /> ecosystems,were detected in the Delta in October 2024 and are now spreading through the SWP.These <br /> mussels pose similar concerns due to their ability to obstruct raw water conveyance facilities and <br /> negatively affect aquatic environments.Although their presence does not typically result in violations of <br /> CITY OF SANTA ANA <br />