DATE: November 19, 2025
TO: Honorable Mayor and City Councilmembers
FROM: Water Utilities Department
TITLE: ACCEPTANCE OF THE REPORT ON WATER QUALITY RELATIVE TO PUBLIC HEALTH GOALS
RECOMMENDATION
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Staff recommends that the City Council receive public comment and accept the report on water quality relative to Public Health Goals.
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BACKGROUND AND ANALYSIS
California public water systems are highly regulated by State and Federal regulations to ensure drinking water quality and protect public health. The California Environmental Protection Agency Office of Environmental Health Hazard Assessment (OEHHA) establishes Public Health Goals (PHGs), and the U.S. Environmental Protection Agency (USEPA) establishes Maximum Contaminant Level Goals (MCLGs) for drinking water contaminants. The PHGs/MCLGs are guidelines and are not requirements for any public water system. Maximum Contaminant Levels (MCLs) set by the State or Federal EPA are the mandatory limits for all public water systems, while PHGs/MCLGs are recommendations and are frequently much lower than the MCLs.
Under provisions of the California Health and Safety Code (HSC § 116470), once every three years, the City is required to prepare a special report (Attachment 2) identifying water quality measurements that have exceeded PHGs or the MCLGs. Additionally, the City must provide an estimate of the cost to reduce the contaminant(s) to the PHG or MCLG. When applicable, in order to reduce the contaminant(s) to the or MCLG, the City will use Best Management Practices (BMP) and/or the Best Available Technology (BAT). The Code also requires that a public water system conduct a public hearing and receive comments from the public relative to the report.
Analysis
For the years 2022, 2023, and 2024, the report shows that Oceanside’s drinking water continues to meet all State Water Resources Control Board Division of Drinking Water (DDW), and USEPA drinking water standards set to protect public health. The City’s drinking water, however, exceeded the PHGs/MCLGs for arsenic and radiologicals such as gross alpha particles, gross beta particles, uranium, and combined radium (radium 226 and radium 228). Additionally, a review of Oceanside’s imported water from the Metropolitan Water District of Southern California (MWDSC), the San Diego County Water Authority (SDCWA), and the Carlsbad Desalination Plant show PHG exceedances for the following constituents: bromate, hexavalent chromium, and radiologicals, including gross alpha, gross beta, combined radium, and uranium. However, it’s important to note that the detected levels for these constituents were well below their respective regulatory MCLs, therefore, this does not constitute a violation of drinking water regulations or indicate the water was unsafe to drink.
Radiologicals
Monitoring results indicate the presence of small amounts of radiologicals in our drinking water; however, those concentrations are well below the MCL and are described in more detail in Attachment 2. Radiologicals are commonly found in ground and surface water due to the natural occurrence in geological formations. The MCL, PHG or MCLG, and the range of detections for each radiological is listed in the table below:
|
Constituent |
MCL |
PHG/MCLG |
Detection Range |
|
Gross Alpha (pCi/L) |
15 |
0 |
ND - 5.5 |
|
Gross Beta (pCi/L) |
50 |
0 |
ND - 8 |
|
Uranium (pCi/L) |
20 |
0.43 |
ND - 5 |
|
Combined Radium (pCi/L) |
5 |
[0.05 & 0.019] |
ND - 2.76 |
The Best Available Technology to treat all radiological constituents is reverse osmosis, which is estimated to cost between $2.2 million per year for Mission Basin Groundwater Purification Facility, to upwards of $14.9 million per year at the Weese Filtration Plant. Staff do not recommend this option due to the cost of treatment.
Arsenic
Arsenic is naturally occurring and can be found in different media such as air, water, soil, and food. Arsenic was detected above the PHG of 0.000004 mg/L but below the MCL in one sample in 2022, and two samples each in 2023 and 2024 from treated water at Weese Filtration Plant, Mission Basin Groundwater Purification Facility, and supplied by Twin Oaks Valley Water Treatment Plant (TOVWTP). The City of Oceanside is in compliance with the MCL of 0.010 mg/L for arsenic.
The approximate cost of arsenic treatment via coagulation-filtration and/or adsorption is estimated to be $11.9 million per year, not including the cost of disposing the waste streams (sludge, backwash) from the treatment facility or the cost of pipelines to consolidate the flows to one location for treatment. However, because the City’s water supply meets MCL standards, this option is not recommended.
Bromate
Bromate has a Public Health Goal (PHG) of 0.1 μg/L and was detected at a range of non-detect to 6.0 μg/L. It is a disinfection byproduct formed during the ozonation of drinking water. According to OEHHA there is no direct epidemiological evidence linking human exposure to bromate compounds with carcinogenic health effects, but bromate is heavily theorized to be linked to cancer due to its chemical properties.
The most effective Best Available Technology for reducing bromate is optimizing the ozonation treatment process. For the City of Oceanside, bromate originates from imported water supplied by the Metropolitan Water District (MWD) and the San Diego County Water Authority (SDCWA). Based on cost estimates provided by the Association of California Water Agencies (ACWA), ozonation treatment would cost approximately $0.17 to $0.36 per 1,000 gallons of water. The City of Oceanside imports about 20,000 AFY of water and based on this quantity, ozonation optimization could cost up to $2.3 million dollars per year.
Chromium VI
Hexavalent chromium has a Public Health Goal (PHG) of 0.02 μg/L. Hexavalent Chromium was detected in imported waters ranging from non-detect to 0.32 μg/L. This heavy metal is found both as a naturally occurring element and as a byproduct of industrial processes. Hexavalent chromium (Chromium-6) is known to be toxic to the liver and carcinogenic.
For the City’s water system, the Best Available Technology to treat hexavalent chromium would be ion exchange. The estimated capital and annual operation and maintenance (O&M) costs for implementing ion exchange at our Robert Weese Filtration facility are projected to range from $0.67 to $1.47 per 1,000 gallons. Based on annually imported water for FY 24/25, the costs would be estimated to cost the city up to $9.6 million dollars.
The City is meeting all Federal and State MCLs required by the EPA and the Division of Drinking Water. Meeting Public Health Goals does not impact the continued compliance of the City’s water quality and safety. As noted above, there is no recommendation by staff to construct or operate facilities to meet theoretical values set by the Public Health Goals.
FISCAL IMPACT
There is no fiscal impact from this report. Should Council direct staff to implement any changes or technological improvements, there could be a significant fiscal impact as previously described in this staff report.
COMMISSION OR COMMITTEE REPORT
The Utilities Commission reviewed staff’s recommendation at its regularly scheduled meeting on July 15, 2025.
CITY ATTORNEY’S ANALYSIS
The referenced documents have been reviewed by the City Attorney and approved as to form.
end
Prepared by: Jordan Alejo, Management Analyst
Reviewed by: Frederick Mayo, Water Utilities Director
Submitted by: Jonathan Borrego, City Manager
ATTACHMENTS:
1. Staff Report
2. Public Health Goals Report