City of Corona • 400 S. Vicentia Ave. Corona, CA 92882 • (951) 736-2400 City of Corona Utilities Department
Report on Water Quality
Relative to Public Health Goals
For 2022-2024
1. IntroducƟon
Under the Calderon-Sher Safe Drinking Water Act of 1996 public water systems in California serving greater than 10,000 connecƟons must prepare a brief report every three years providing informaƟon on any consƟtuents that exceed a Public Health Goal (PHG) in the preceding three years.
The report must contain informaƟon on detecƟon of any contaminant in drinking water at a level exceeding a Public Health Goal, esƟmate of costs to remove detected contaminants to below the PHG using Best Available Technology (BAT), and the health risk for each contaminant exceeding a PHG. This report has been prepared to address the requirements set forth in SecƟon 116470 of the California Health and Safety Code. It is based on water quality analysis during calendar years 2022, 2023, and 2024. There are no regulaƟons detailing the requirements for the preparaƟon of Public Health Goal reports. The AssociaƟon of California Water Agencies Water Quality CommiƩee has prepared suggested guidelines for water uƟliƟes to use in preparing Public Health Goal Reports. These guidelines were used in the preparaƟon of this report.
2. California Drinking Water Regulatory Process
California Health and Safety Code SecƟon 116365 requires the State to develop a Public Health Goal for every contaminant with a primary drinking water standard or for any contaminant California is proposing to regulate with a primary drinking water standard. PHGs are set by the California Office of Environmental Health Hazard Assessment (OEHHA) and are based solely on public health risk consideraƟons. None of the pracƟcal risk-management factors that are considered by the United States Environmental ProtecƟon Agency (USEPA) or the California Division of Drinking Water (DDW) in seƫng drinking water standards are considered in seƫng the PHGs. These factors include analyƟcal detecƟon capability, available treatment technology, benefits, and costs. The PHGs are not enforceable and are not required to be met by any public water system. Maximum Contaminant Level Goal (MCLG) is the federal equivalent to PHG.
City of Corona • 400 S. Vicentia Ave. Corona, CA 92882 • (951) 736-2400
3. IdenƟficaƟon of Contaminants
SecƟon 116470(b)(1) of the Health and Safety Code requires public water systems serving more than 10,000 connecƟons to idenƟfy each contaminant present in drinking water that was above the Public Health Goal. The consƟtuents presented in this secƟon were detected at one or more locaƟons in our drinking water system at levels that exceeded the PHG or the MCLG. Arsenic: It is a chemical naturally occurring in groundwater due to erosion; runoff from orchards; glass and electronics producƟon wastes. The PHG for arsenic is 0.004 parts per billion (ppb) and the Maximum Contaminant Level (MCL) is 10 ppb. Arsenic was detected above the PHG in the local groundwater: Wells 7A, 8A, 9A, 11A, 12A, 15, 17A, 19, 22, 25, 26, 28, 29, 31, and 33. Average Arsenic detected in groundwater was 2.06 ppb.
Gross Alpha ParƟcle AcƟvity (gross alpha): It is a measure of the total amount of radioacƟvity in a water sample aƩributable to the radioacƟve decay of alpha-emiƫng elements. It naturally occurs in groundwater due to erosion. The MCLG is zero and the MCL is 15 picocuries per liter (pCi/L). Gross alpha was detected in the local groundwater: Wells 8A, 9A, 17A, 19, 22, 25, 26, 31, and 33. Average gross alpha detected in groundwater was 4.36 pCi/L.
Coliform Bacteria: Coliform bacteria are a group of indicator organisms that are ubiquitous in nature and are not generally considered harmful. Coliform bacteria are oŌen referred to as “indicator organisms” because they indicate the potenƟal presence of disease-causing bacteria in water. They are used because of the ease in monitoring and analysis. The MCLG is zero and the MCL is 5% of the samples collected monthly. The City collects between 120 and 150 rouƟne coliform bacteria samples every month.
During 2022, no more than 1% of these samples were posiƟve in a month. During 2023, no more than 1% of these samples were posiƟve in a month. During 2024, no more than 0% of these samples were posiƟve in a month. The UƟliƟes Department maintains an effecƟve cross connecƟon control program, a disinfectant residual throughout the system, an effecƟve monitoring and surveillance program, and posiƟve pressure in all parts of the distribuƟon system.
Hexavalent Chromium: Hexavalent chromium is a toxic form of the element chromium. Hexavalent chromium compounds are man-made and widely used in many different industries. The PHG for Hexavalent chromium is 0.02 ppb, there is currently no MCL set. Hexavalent Chromium was detected above the PHG in the local groundwater: Wells 7A, 8A, 9A, 11A, 12A, 15, 17A, 19, 22, 25, 28, 29, 31, and 33.
Average hexavalent chromium detected in groundwater was 0.885 ppb. Perchlorate: Perchlorate is a chemical that can occur naturally in the environment and also may be released by fireworks, improper handling or disposal of rocket fuel, and various industrial processes. The PHG for Perchlorate is 1 ppb, the MCL is 6 ppb.
Perchlorate was detected above the PHG in the local groundwater: Wells 7A, 8A, 9A, 11A, 12A, 14, 17A, 19, 22, 25, 27, 28, 29, 31, 33. Average Perchlorate detected in groundwater was 5.12 ppb.
City of Corona • 400 S. Vicentia Ave. Corona, CA 92882 • (951) 736-2400 Uranium: Uranium is a radioacƟve compound that naturally occurs in varying amounts in the earth’s crust. The PHG for Uranium is 0.43pCi/L, the CA MCL is 20 pCi/L.
Uranium was detected above the PHG in the local groundwater: Wells 8A, 9A, 11A, 15, 17A, 19, 25, 26, 31, 33. Average Uranium detected in groundwater was 5.7 pCi/L. 1,2,3-Trichloropropane (1,2,3-TCP): 1,2,3-TCP is a manmade chemical found at industrial or hazardous waste sites. It has been used as a cleaning and degreasing solvent and is also associated with pesƟcide products. 1,2,3 TCP is likely to either leach from soil into groundwater or evaporate from soil surfaces. The PHG for 1,2,3-TCP is
0.0007 ppb, the CA MCL is 0.005 ppb. 1,2,3-TCP was detected above the PHG in the local groundwater: Wells 8A, 17A, 19, 33. Average 1,2,3-TCP detected in groundwater was 0.12 ppb.
Fluoride: Fluoride is a naturally occurring element, dissolved into drinking water via erosion of natural deposits. The PHG for fluoride is 1,000 ppb, the CA MCL is 2,000 ppb. Fluoride was detected above the PHG in the local groundwater: Wells 26. Average Fluoride detected in groundwater was 2,000 ppb.
Perfluorooctanoic Acid (PFOA): A type of compound that is part of the PFAS family, for many years PFOA were widely used in industrial applicaƟons and consumer products.
The PHG for PFOA is 0.000007 ppb, there is no CA MCL. PFOA was detected above the PHG in the local groundwater: Wells 7A, 8A, 9A, 11A, 15, 17A, 19, 22, 25, 26, 28, 29, 31, and 33. Average POFA detected in groundwater was 3.3 ppb. Perfluorooctane Sulfonic Acid (PFOS): A type of compound that is part of the PFAS family, for many years PFOS were widely used in industrial applicaƟons and consumer products. The PHG for PFOS 0.001 ppb, there is no CA MCL. PFOS was detected above the PHG in the local groundwater: Wells 7A, 8A, 9A, 11A, 15, 17A, 19, 22, 25, 26, 28, 29, 31, and 33. Average PFOS detected in groundwater was 3.8 ppb. Tetrachloroethylene (PCE):Tetrachloroethylene (PCE) is most oŌen used for dry cleaning and texƟle processing as a chemical intermediate, and for vapor degreasing in metal cleaning operaƟons. The PHG for PCE is 0.06 ppb, the CA MCL is 5 ppb. PCE was detected above the PHG in the local groundwater: Wells 19 and 25. Average PCE detected in groundwater was 0.69 ppb.
Thallium: Thallium is a natural element found in ores deep underground. In the environment, thallium is found joined with other elements such as bromine, chlorine, fluorine and iodine. Thallium is used in the producƟon of electronics, glass, and pharmaceuƟcals. The PHG for Thallium is 0.1 ppb, the CA MCL is 2 ppb. Thallium was detected above the PHG in the local groundwater: Well 12A. Average Thallium detected in groundwater was 0.67 ppb.
4. Numerical Public Health Risks
City of Corona • 400 S. Vicentia Ave. Corona, CA 92882 • (951) 736-2400 SecƟon 116470(b)(2) of the Health and Safety Code requires disclosure of the numerical public health risk determined by the OEHHA associated with the maximum contaminant levels, acƟon levels, public health goals, and maximum contaminant level goals. Arsenic: The OEHHA has determined that the health risk associated with the PHG is one excess case of cancer in a million people and the risk associated with the MCL is 2.5 excess cases of cancer in 1,000 people exposed for a 70-year lifeƟme. Gross Alpha ParƟcle AcƟvity (gross alpha): The USEPA has determined that the health risk associated with the MCLG is zero and the risk associated with the MCL is one excess case of cancer in 1,000 people over a lifeƟme exposure. Coliform Bacteria: Coliform is only a surrogate indicator of the potenƟal presence of pathogens; it is not possible to state a specific numerical health risk. While USEPA normally sets MCLGs “at a level where no known or anƟcipated adverse effects on persons would occur,” they indicate that they cannot do so with coliforms. The reason for the coliform drinking water standard is to minimize the possibility of the water containing pathogens which are organisms that cause waterborne disease. Hexavalent Chromium: The California Department of Public Health and USEPA have determined that Chromium Six is a health concern at certain levels of exposure. The category of health risk associated with Chromium Six is that conƟnued exposure to Chromium Six could result in allergic dermaƟƟs (skin reacƟons) and has been found to cause gastrointesƟnal tumors in rats and mice. The numerical health risk for cancer aƩached to levels above the PHG is 1x10−6 which means one excess cancer case per million people exposed.
Perchlorate: Perchlorate is a chemical that can occur naturally in the environment and also may be released by fireworks, improper handling or disposal of rocket fuel, and various industrial processes. Perchlorate is known to block the thyroid’s ability to take in and process iodide, which is a nutrient essenƟal to brain development, growth, heart funcƟon, and other systems.
Uranium: Uranium is a radioacƟve compound that naturally occurs in varying amounts in the earth’s crust. People who drink water containing uranium in excess of the MCL over many years may have kidney problems or an increased risk of geƫng cancer. The cancer risk associated with drinking water with uranium greater than the MCL of 20 pCi/L is 5x10-5, or five surplus cancer cases per hundred thousand people who drink water in excess of the MCL over a lifeƟme. The cancer risk for uranium at the PHG of
0.43 pCi/L is 1x10-6, or one surplus cancer case per million people drinking water in excess of the PHG over a lifeƟme.
1,2,3 – Trichloropropane (1,2,3-TCP): It is a manmade chemical, typically found at industrial or hazardous waste sites. The PHG developed is based on carcinogenic effects observed in animals, significant tumors have been observed in a number of Ɵssues in male and female mice and rates administered 1,2,3-TCP by the oral route.
City of Corona • 400 S. Vicentia Ave. Corona, CA 92882 • (951) 736-2400 Fluoride: Fluoride can be disƟnguished from other chemicals for which PHGs are developed in that it can be present as an intenƟonal addiƟve rather than a “contaminant.” Fluoride is added to drinking water at levels close to 1 mg/L in order to protect children and adults against dental caries. When administered orally to laboratory animals, fluoride has adverse health effects on bones and teeth as well as the kidneys and stomach. Oral administraƟon of fluoride at high levels affects survival and body weight gain. Excess oral exposure to fluoride can lead to dental fluorosis. Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS): For more than a half-century, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were widely used in industrial applicaƟons and consumer products, notably, PFOA in nonsƟck cookware and PFOS in stain and water-repellant fabrics and in firefighƟng foams. ScienƟfic studies show adverse health effects of PFOA and PFOS in people exposed at environmental levels, and similar effects in laboratory animals. There is evidence from epidemiologic studies that exposure to PFOA increases the risk of kidney cancer. PFOS is associated with immune system toxicity and increased total cholesterol in humans, with suggesƟve evidence of an associaƟon with risk of preeclampsia and pregnancy-related hypertension. The effects seen in humans are supported by studies in laboratory animals, which show that PFOA and PFOS can cause liver toxicity, immunotoxicity, thyroid toxicity, developmental/reproducƟve toxicity, and cancer.
Tetrachloroethylene (PCE): A public health goal (PHG) was established for tetrachloroethylene (PCE, also known as perchloroethylene) in drinking water. The PHG is based on carcinogenic effects observed in experimental animals. Exposure to PCE is carcinogenic for rodents, inducing liver cancer in mice by inhalaƟon or ingesƟon, and leukemia in rats by inhalaƟon.
Thallium: The PHG is based on a noncancer health endpoint observed in female rats administered thallium daily by gavage for 90 days. In the study, alopecia, or hair loss, was observed in both male and female rats which is a classic sign of thallium poisoning.
5. IdenƟficaƟon of Risk Categories
SecƟon 116470(b)(3) of the Health and Safety Code requires idenƟficaƟon of the category of risk to public health associated with exposure to the contaminant in drinking water.
6. DescripƟon and Cost of Best Available Technology.
SecƟon 116470(b)(4) of the Health and Safety Code requires a descripƟon of the best available technology to remove or reduce the concentraƟons of the contaminants idenƟfied in this report as exceeding the set parameters. SecƟon 116470(b)(5) of the Health and Safety Code requires an esƟmate of the addiƟonal cost and addiƟonal cost per customer if uƟlizing the best available technology to reduce the concentraƟon of a contaminant to a level at or below the PHG or the MCLG. Both the USEPA and DDW adopt best available technologies, BATs, which are the City of Corona • 400 S. Vicentia Ave. Corona, CA 92882 • (951) 736-2400 best-known methods for reducing contaminant levels to the MCL. Many MCLGs and PHGs are set to a numerical value far below the respecƟve DetecƟon Limit for Purposes of ReporƟng (DLRs).
This makes it difficult to know if a consƟtuent was actually lowered to zero.
The Best Available Technology (BAT) to lower the level of arsenic, gross alpha, hexavalent chromium, uranium, and Fluoride below the PHG is reverse osmosis (RO). Current levels are already below the MCL; reverse osmosis is one opƟon in trying to lower the levels even further to below the PHG. Cost esƟmaƟng guides from the AssociaƟon of California Water Agencies (ACWA) guidance report were used in determining the esƟmated cost to implement addiƟonal RO. Please note cost esƟmates are theoreƟcal. According to the cost esƟmates, provided by ACWA, to install and operate an RO system it would cost anywhere between $2.28 - $8.99 per 1,000 gallons of water treated. The esƟmated annualized capital, operaƟon, and maintenance costs for the City to install, run, and maintain would range from $23 million/year to $90 million/year. The cost per customer connecƟon would range from $511 to $2,016 per year.
The Best Available Technology (BAT) to lower the level of Perchlorate, PFOA, PFOS, and Thallium below the PHG is Ion Exchange (IE). Cost esƟmaƟng guides from the AssociaƟon of California Water Agencies (ACWA) guidance report were used in determining the esƟmated cost to implement addiƟonal IE. Please note cost esƟmates are theoreƟcal. According to the cost esƟmates, provided by ACWA, to install and operate an IE system it would cost anywhere between $0.98- $2.68 per 1,000 gallons of water treated. The esƟmated annualized capital, operaƟon, and maintenance costs for the City to install, run, and maintain would range from $9.8 million/year to $27 million/year. The cost per customer connecƟon would range from $220 to $601 per year.
The Best Available Technology (BAT) to lower the level of 1,2,3 TCP and PCE below the PHG is AcƟvated Carbon (AA). Cost esƟmaƟng guides from the AssociaƟon of California Water Agencies (ACWA) guidance report were used in determining the esƟmated cost to implement addiƟonal AA. Please note cost esƟmates are theoreƟcal. According to the cost esƟmates, provided by ACWA, to install and operate an AA system it would cost anywhere between $0.36 - $3.03 per 1,000 gallons of water treated. The esƟmated annualized capital, operaƟon, and maintenance costs for the City to install, run, and maintain would range from $3.6 million/year to $31 million/year. The cost per customer connecƟon would range from $80 to $680 per year.
The BAT for inacƟvaƟng coliform bacteria in drinking water as determined by the State is the protecƟon of wells from coliform contaminaƟon, maintenance of a disinfectant residual throughout the distribuƟon system, proper maintenance of the distribuƟon system, and filtraƟon and/or disinfecƟon of surface and groundwater. The City already disinfects all water served to the public. The City adds chloramines, and maintains a chloramine residual, to the distribuƟon system used to deliver drinking water to ensure the water is microbiologically safe. The chloramine residual levels are carefully controlled to provide the best health protecƟon without causing the water to have undesirable taste and odor or increasing the DisinfecƟon By Product (DBPs) levels.
Other equally important measures that have been implemented include: an effecƟve crossconnecƟon control program, an effecƟve monitoring program, a successful tank cycling program, rouƟne dead-end flushing program, and maintaining posiƟve pressure in our distribuƟon system.
City of Corona • 400 S. Vicentia Ave. Corona, CA 92882 • (951) 736-2400
7. RecommendaƟons for Further AcƟon:
SecƟon 116470(b)(6) of the Health and Safety Code requires a brief descripƟon of any acƟons the water purveyor intends to take to reduce the concentraƟon of the contaminant and the basis for that decision. The drinking water quality for the City of Corona meets all drinking water standards set to protect public health. To further reduce the levels of the consƟtuents idenƟfied in this report that are already significantly below the health-based Maximum Contaminant Levels established to provide "safe drinking water", addiƟonal costly treatment processes would be required. The effecƟveness of the treatment processes to provide any significant reducƟons in consƟtuent levels at these already low values is uncertain. The health protecƟon benefits of these further hypotheƟcal reducƟons are not at all clear and may not be quanƟfiable. Therefore, no acƟon is proposed.
Table 1
Average Range
Arsenic ppb 0.004 10 1.86 ND – 4.3 C one per million 2.5 per thousand AA,C/F,IE,LS,RO
Gross Alpha
Particle Activity pCi/L 0 15 11.6 3.1 - 19.3 C zero one per thousand RO Total Coliform % samples
positive 0 5 0 0 NA NA NA RO
Hexavalent
Chromium μg/L 0.02 none 0.75 .029 - 3.35 C one per million NA C/F, IE, RO Perchlorate ug/L 1 6 5.50 1.9 - 9.1 NA NA NA IE
Uranium pCi/L 0.43 20 9.7 0.84 - 20.5 C one per million one per
hundred
thousand
C/F, IE, RO, LS
1,2,3-TCP ppb 0.0007 0.005 0.012 ND - 0.01 C one per million seven per million AA
Fluoride ppm 1 2 2.000 0.1 - 2.3 NA NA NA RO
PFOA ppb 0.000007 NA 3.30 ND - .243 NA NA NA AA,IE
PFOS ppb 0.001 NA 3.80 ND - .285 NA NA NA AA,IE
PCE ppb 0.06 5 0.69 N - 1 C one per million
eight per
hundred
thousand
AA
Thallium ppb 0.1 2 0.67 ND - 0.67 NA NA NA IE
Table 2
Arsenic RO $23,003,449 $90,702,196 $511 $2,016
Gross Alpha
Particle Activity RO $23,003,449 $90,702,196 $511 $2,016 Hexavalent
Chromium RO $23,003,449 $90,702,196 $511 $2,016
Perchlorate IE $9,887,447 $27,039,142 $220 $601
Uranium RO $23,003,449 $90,702,196 $511 $1,144
1,2,3-TCP AA $3,632,124 $30,570,373 $80 $680
Fluoride RO $23,003,449 $90,702,196 $511 $2,016
PFOA IE $9,887,447 $27,039,142 $220 $601
PFOS IE $9,887,447 $27,039,142 $220 $601
PCE AA $3,632,124 $30,570,373 $80 $680
Thallium IE $9,887,447 $27,039,142 $220 $601
RISK CATEGORIES TREATMENT TECHNOLOGIES
AA: Activated Carbon
C/F: Coagulation/Filtration
ABBREVIATION IE: Ion Exchange
PHG: Public Health Goal LS: Lime Softening
MCL: Maximum Contaminant Level RO: Reverse Osmosis
MCLG: Maximum Contaminant Level Goal
μg/L: Micrograms per liter
pCi/L: picoCuries per liter
ND: No Detection
PARAMETER Annualized Capital and O&M Costs
Ranges
TREATMENT
TECHNOLOGY
*Results shown are from raw groundwater samples. The Utilities Department (UD) treats and blends groundwater before it is delivered to customers. The UD has five blending facilities that blend treated groundwater sources with raw groundwater sources and treated surface water to deliver safe, reliable drinking water to customer’s tap.
C (Carcinogen): A substance that is capable of producing cancer
Ranges
Additional Costs per Connection per Year
2025 PUBLIC HEALTH GOAL REPORT
City of Corona Utilities Department
PARAMETER
CONCENTRATION
CATEGORY OF RISK
CANCER RISK
AT PHG or
MCLG
CANCER RISK
AT MCL
BEST AVAILABLE
TECHNOLOGIES
UNITS OF
MEASUREMENT
PHG OR
(MCLG) MCL