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<br /> <br /> <br />City of Santa Ana 3 2025 PHGs Report <br /> <br /> Bromate – formed when naturally-occurring bromide reacts with ozone during the <br />disinfection process in treated surface water purchased from the Metropolitan Water <br />District of Southern California (MWDSC). <br /> Gross alpha particle activity (gross alpha) – naturally-occurring in local groundwater <br />and in treated surface water purchased from MWDSC. <br /> Gross beta particle activity (gross beta) – naturally-occurring in treated surface water <br />purchased from MWDSC; not required to be tested in local groundwater. <br /> Hexavalent Chromium – naturally-occurring in local groundwater. <br /> Perchlorate – industrial contamination in local groundwater. <br /> Perfluorooctanesulfonic acid (PFOS) – industrial contamination in local groundwater. <br /> Perfluorooctanoic acid (PFOA) – industrial contamination in local groundwater. <br /> Radium, Combined, is the sum of Radium-226 and Radium-228 – naturally-occurring in <br />treated surface water purchased from MWDSC. <br /> Uranium – naturally-occurring in local groundwater and in treated surface water <br />purchased from MWDSC. <br /> <br />The accompanying table shows the applicable PHG or MCLG and MCL for each contaminant <br />identified above. The table includes the maximum, minimum, and average concentrations of <br />each contaminant in drinking water supplied by the City in calendar years 2022 through 2024. <br /> <br />4.0 Numerical Public Health Risks <br /> <br />Section 116470(b)(2) of the Health and Safety Code requires disclosure of the numerical public <br />health risk, determined by OEHHA, associated with the MCLs, PHGs and MCLGs. Available <br />numerical health risks developed by OEHHA for the contaminants identified above are shown <br />on the accompany table. Only numerical risks associated with cancer-causing chemicals have <br />been quantified by OEHHA. <br /> <br />Arsenic – OEHHA has determined the health risk associated with the PHG is 1 excess case of <br />cancer in a million people and the risk associated with the MCL is 2.5 excess cases of cancer in <br />1,000 people exposed over a 70-year lifetime. <br /> <br />  <br />  <br />City Council 23 – 6 11/4/2025