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<br />proposing to regulate with a primary drinking water standard. A PHG is the level of a <br />contaminant in drinking water that poses no significant health risk if consumed for a lifetime. <br />The process of establishing a PHG is a risk assessment based strictly on human health <br />considerations. PHGs are recommended targets and are not required to be met by any public <br />water system. <br />The State office designated to develop PHGs is the California Environmental Protection <br />Agency’s Office of Environmental Health Hazard Assessment (OEHHA). The PHG is then <br />forwarded to the State Water Resources Control Board, Division of Drinking Water (DDW) for <br />use in revising or developing a Maximum Contaminant Level (MCL) in drinking water. The MCL <br />is the highest level of a contaminant that is allowed in drinking water. State MCLs cannot be <br />less stringent than federal MCLs and must be as close as is technically and economically <br />feasible to the PHGs. DDW is required to take treatment technologies and cost of compliance <br />into account when setting an MCL. Each MCL is reviewed at least once every five years. <br />Two radiological contaminants (gross alpha particle activity and gross beta particle activity) <br />have MCLs but do not yet have designated PHGs. For these contaminants, the Maximum <br />Contaminant Level Goal (MCLG), the federal U.S. Environmental Protection Agency (USEPA) <br />equivalent of PHGs, is used in the 2025 PHGs Report. <br />3.0 Identification of Contaminants <br />Section 116470(b)(1) of the Health and Safety Code requires public water systems serving <br />more than 10,000 service connections to identify each contaminant detected in drinking water <br />that exceeded the applicable PHG. Section 116470(f) requires the MCLG to be used for <br />comparison if there is no applicable PHG. <br />The City of Santa Ana (City) water system has approximately 45,652 service connections. The <br />following constituents were detected at one or more locations within the drinking water system <br />at levels that exceeded the applicable PHGs or MCLGs: <br />Arsenic – naturally-occurring in local groundwater. <br />City of Santa Ana 2 2025 PHGs Report