Report on Water Quality
Relative
to Public Health
Goals
June 2025
CITY OF STOCKTON
Q ,
MUNICIPAL UTILITIES DEPARTMENT
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TABLE OF CONTENTS
SEC
TION PAGE
BACKGROUND ....................................................................................................................... 3 PUBLIC HEALTH GOALS ....................................................................................................... 3 CITY OF STOCKTON WATER SOURCES ............................................................................. 4 WATER QUALITY DATA CONSIDERED ................................................................................ 4 GUIDELINES FOLLOWED ...................................................................................................... 4 BEST AVAILABLE TREATMENT TECHNOLOGY AND COST ESTIMATES .......................... 4
CONTAMINANTS DETECTED THAT EXCEED A PUBLIC HEALTH GOALS OR MAXIMUM CONTAMINANT LEVEL GOALS ............................................................................................. 4 Arsenic ........................................................................................................................ 5 Bromate ....................................................................................................................... 6 Radionuclides .............................................................................................................. 6 Gross Alpha ............................................................................................................ 7 Radium-228 ............................................................................................................ 7 Uranium .................................................................................................................. 8 Total Coliforms ............................................................................................................ 9 RECOMMENDATIONS FOR FURTHER ACTION ................................................................ 10
APPENDICES
APPENDIX A - MCLs, DLRs and PHGs for Regulated Drinking Water Contaminants APPENDIX B - Health Risk Information for Public Health Goal Exceedance Reports APPENDIX C - Cost Estimates for Treatment for Treatment Technologies EXHIBIT 1
CITY OF STOCKTON WATER SYSTEM
REPORT ON WATER QUALITY
RELATIVE TO PUBLIC HEALTH GOALS
June 2025
BACKGROUND
Provisions of California Health and Safety Code Section 116470(b) require that public water systems serving more than 10,000 service connections prepare a brief, written report by July 1, 2025 that provides information on water quality levels from the three previous years that exceeded any Public Health Goals (PHGs), published by the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA). The law also requires that where OEHHA has not adopted a PHG for a contaminant, water suppliers are to use the Maximum Contaminant Level Goals (MCLGs) set by the United States Environmental Protection Agency (USEPA). Only contaminants in a water system which have a level exceeding a PHG or MCLG are addressed in this report.
T
his report provides the following information as specified in the California Health and Safety Code Section 116470(b) for any contaminant detected in the City's water supply between 2022 and 2024 at a level exceeding a PHG or MCLG:
• N
umerical public health risk associated with the Maximum Contaminant Level (MCL), and the PHG or MCLG,
• Category or type of risk to health that could be associated with each contaminant level, • Best Available Treatment Technology that could be used to reduce the contaminant level, and
• Estimate of the cost to install that treatment.
P
UBLIC HEALTH GOALS
PHGs are set by the California OEHHA and are based solely on public health risk considerations. None of the practical risk management factors that are considered by the USEPA or the California State Water Resources Control Board (SWRCB) Division of Drinking Water (DDW) in setting drinking water standards are considered in setting the PHGs. These factors include analytical detection capability, treatment technology available, benefits, and costs. PHGs are not enforceable and are not required to be met by any public water system.
MCLGs are the federal equivalent to PHGs. Appendix A lists the regulated contaminants for which PHGs and MCLGs have been set.
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CITY OF STOCKTON WATER SOURCES
Most of the City’s drinking water is treated surface water produced through the Delta Water Treatment Plant (DWTP) or purchased from the Stockton East Water District (SEWD). Water is diverted from the Sacramento-San Joaquin Delta, and Mokelumne River water is purchased from Woodbridge Irrigation District for treatment at the City’s DWTP. SEWD imports surface water from New Melones and New Hogan Reservoirs for treatment and delivery to the City.
The City of Stockton’s water supply also consists of groundwater sources.
W
ATER QUALITY DATA CONSIDERED
All water quality data collected from the City’s treated surface water and groundwater between 2022 and 2024 for purposes of determining compliance with drinking water standards were considered for this report. In addition, water quality data from SEWD is also considered for this report. This data is summarized in the 2022, 2023, and 2024 annual Drinking Water Quality Reports (i.e., Consumer Confidence Reports) which are available on the City’s website. Copies of these reports may be viewed at the following location:
https://cms3.revize.com/revize/stockton/Documents/Services/Water,%20Sewer%20&%20St ormwater/Water/Water%20Quality/ccr.pdf
GUIDELINES FOLLOWED
Suggested Guidelines for Preparation of Required Reports on Public Health Goals (PHGs) to satisfy requirements of California Health and Safety Code Section 116470(b) by the Association of California Water Agencies was used in the preparation of this report.
P
HGs, MCLGs and DLRs
PHGs are based solely on public health risk considerations. They represent the level of a contaminant in drinking water below which there is no known or expected significant risk to health. None of the practical risk -management factors that are considered by the DDW or USEPA in setting drinking water MCLs are considered in setting PHGs. These factors include analytical detection capability, available treatment technologies, and benefits and costs of operating the treatment. MCLGs are the federal equivalent to PHGs, however, in cases where a contaminant is a known or suspected carcinogen, the MCLG is set to zero. PHGs and MCLGs are not enforceable and are not required to be met by any public water systems. A constituent’s DLR (Detection Limits for Purposes of Reporting) is the designated minimum level at or above which any analytical result for drinking water must be reported to DDW. PHG report guidance recommends considering results that are above their PHG or MCLG and less than their DLR to be zero. A list published by DDW of regulated constituents with the MCLs, DLRs and PHGs for Regulated Drinking Water Contaminants is included as Attachment 2.
BEST
AVAILABLE TREATMENT TECHNOLOGY AND COST ESTIMATES
Both the USEPA and SWRCB adopt Best Available Technologies (BATs) which are the best- known methods of reducing contaminant levels to the MCL. Costs can be estimated for such technologies. However, since many PHGs and all MCLGs are set much lower than the MCL, it is not always possible, nor feasible, to determine what treatment is needed to further reduce a contaminant to or near the PHG or MCLG, many of which are set at zero. Estimating the costs to reduce a contaminant to zero is difficult, if not impossible and costly. In some cases, installing treatment to try and further reduce to very low levels of one contaminant may have adverse EXHIBIT 1
effects on other aspects of water quality.1
CONTAMINANTS DETECTED THAT EXCEED A PUBLIC HEALTH GOALS OR MAXIMUM
CONTAMINANT LEVEL GOALS
The following is a discussion of contaminants that were detected in one or more of our drinking water sources at levels above the PHG, or if no PHG, above the MCLG. This report only provides information on contaminants that were found in the City’s drinking water system to have exceeded established PHG or MCLG. The City of Stockton consistently delivers safe water at the lowest possible cost to our customers. The levels of these contaminants were well below the MCLs, so this does not constitute a violation of drinking water regulations or indicate the water was unsafe to drink. These results could be considered typical for a California water agency. The health risk information for regulated contaminants with PHGs are provided in Appendix B.
Arsenic
The PHG for arsenic is 0.004 µg/L, and United States Environmental Protection Agency and State of California MCL is 10 µg/L. Arsenic is a naturally occurring element and is widely present in the environment. In certain geographical areas, natural mineral deposits may contain large quantities of arsenic and this may result in higher levels of arsenic in water. The main commercial use of arsenic in the United States is pesticides and in wood preservatives.
In humans, while ingestion of larger doses of arsenic may be lethal, lower levels of exposure may cause a variety of systemic effects including irritation of the digestive tract, nausea, vomiting, and diarrhea. In addition, arsenic ingestion can increase the risk of cancer in the digestive system, lungs, heart, and skin. The duration of arsenic exposure appears to be a key factor in determining the extent of the toxic effects.
The City of Stockton is required to monitor each of its drinking water wells for arsenic at least once every three years. In sampling conducted in 2022, 2023 and 2024, nine (9) samples were collected from a total of nine (9 ) active well sites. Arsenic values ranged from 2 µg/L to a maximum of 6.4 µg/L, with an average concentration of 4.5 µg/L over the three-year span. The MCL is 10 µg/L on a quarterly running average.
Samples collected from SEWD treated surface water had no detections of arsenic.
Health Risk Category
The health risk category for arsenic is carcinogenicity. People who drink water containing arsenic above the MCL throughout their lifetime could experience an increased risk of getting cancer.
Numerical Health Risk at MCLG
The numerical health risk for arsenic based on the PHG is 1 x 10 -6. This means one excess
cancer case per million people exposed.
1 The estimated service connection costs were derived from adjusting the 2022 Public Health Goals Report’s estimated service connection costs with respects to the Updated 2012 ACWA Cost of Treatment Table (Attachment A, Table 3).
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Best Available Technologies and Treatment Costs
The BAT to lower the level of arsenic below the MCL is the addition of ion exchange treatment units. The estimated annual cost to install and operate ion exchange treatment units at 9 of the City’s wells to reduce arsenic levels to below the PHG would be approximately $0.82 per 1,000 gallons of water treated, which includes annualized cost of construction, plus operation and maintenance costs. This translates into an additional annual cost of approximately $248 per service connection per year for the life of the treatment system.
B
romate
The PHG for bromate is 1 µg/L and MCL is 10 µg/L calculated on a quarterly running average.
Bromate is formed when naturally occurring bromide reacts with ozone in the surface water treatment process. The City uses ozone in the treatment process at the Delta Water Supply Treatment Plant.
I
n sampling conducted at the DWTP from 2022 to 2024, a total of thirty-six (36) samples were collected. Bromate values ranged from <5 µg/L to 24 µg/L with an average of <6.1 µg/L over the three-year span. The City is complying of the MCL, as the quarterly running average is below 10 µg/L.
H
ealth Risk Category
The health risk category for bromate is carcinogenicity. People who drink water containing bromate above the MCL throughout their lifetime could experience an increased risk of getting cancer.
Nu
merical Health Risk at MCLG
The numerical health risk for bromate based on the PHG is 1 x 10 -6. This means one excess cancer case per million people exposed.
B
est Available Technologies and Treatment Costs
The BAT to lower the level of bromate below the MCL is the addition of granular activated carbon treatment units. The estimated annual cost to install and operate a granular activated carbon treatment unit at the Delta Water Supply Treatment Plant to reduce bromate levels to below the PHG would be approximately $0. 77 per 1,000 gallons of water treated, which includes annualized cost of construction, plus operation and maintenance costs. This translates into an additional annual cost of approximately $174 per service connection per year for the life of the treatment system, assuming the treatment plant operates 365 days of the year.
Radionuclides
Many naturally occurring substances and a few man- made ones have the potential to emit ionizing radiation, and therefore, are referred to as radioactive. Of the radionuclides that have been observed in drinking water, most are naturally occurring. The naturally occurring contaminant of greatest concern in drinking water is uranium. Most of the naturally occurring radionuclides are alpha particle emitters.
C
ontamination by man-made nuclear materials can also occur. The man-made radionuclides, which are primarily beta and photon emitters, are produced by several activities that involve EXHIBIT 1
the use of concentrated radioactive materials. These include production of electricity; nuclear medicines used in therapy and diagnosis; and various commercial products such as, televisions and smoke detectors. The City of Stockton is only required to monitor its groundwater and surface water supplies for naturally occurring radionuclides.
Exposure to radionuclides from drinking water results in an increased risk of cancer. In addition to cancer, exposure to uranium has the potential to cause kidney damage. In California, the radionuclides currently regulated in drinking water are gross alpha particle activity, radium 226, radium 228, uranium, and beta and photon emitters. The City detected Gross Alpha Particles, Radium-228, and Uranium above the PHG or MCLG but well under the MCL.
Gross Alpha Particles
Radionuclides such as gross alpha particles in water supplies are predominantly from erosion of natural deposits. The term radionuclide refers to naturally occurring elemental radium, radon, uranium, and thorium with unstable atomic nuclei that spontaneously decay, producing ionizing radiation. Gross alpha is defined as the sum total of these radionuclides. The MCL for gross alpha is 15 picocuries per liter of water (pCi/L) and the MCLG is 0 pCi/L.
The City collected and analyzed samples for gross alpha particles during 2022-2024, with values that ranged from 1.50 pCi/L to 5.13 pCi/L, with an average value of 4.17 pCi/L, all sample results were below the MCL.
Health Risk Category
The category of health risk for gross alpha particles is carcinogenicity chronic toxicity.
Carcinogenic risk means capable of producing cancer. Chronic toxicity means that adverse effects may develop gradually from low levels of exposure over a long period of time.
Numerical Health Risk at MCLG
The numerical health risk based on USEA’s MCLG is zero therefore the cancer risk is zero.
Best Available Technologies and Treatment Costs
The best available technology (BAT) to lower the level of these compounds below the PHG is reverse osmosis. Since the levels are already below the MCL, reverse osmosis would be required to attempt to lower the levels to below the PHG. Please note that accurate cost estimates are difficult, if not impossible, and are highly speculative and theoretical. The estimated annual cost to install and operate reverse osmosis system at 13 of the City’s wells to reduce uranium levels to below the PHG would be approximately $5.31 per 1,000 gallons of water treated, which includes annualized cost of construction, plus operation and maintenance costs. This translates into an additional annual cost of approximately $1510 per service connection per year for the life of the treatment system.
Radium-228
Radium-228 is a naturally occurring radioactive element present in geological formations and the earth’s crust. It is introduced into groundwater and surface water through erosion. The MCL for Radium-228 is a combined total of Radium -226 + Radium-228 is 5 pCi/L and the PHG for Radium-228 is 0.019 pCi/L.
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The City collected and analyzed samples for Radium-228 during 2022-2024, with values that ranged from ND to 1.71 pCi/L, with an average result of 0.50 pCi/L, with all samples below the MCL.
He
alth Risk Category
The category of health risk for uranium is carcinogenicity chronic toxicity (kidneys).
Carcinogenic risk means capable of producing cancer. Chronic toxicity means that adverse effects may develop gradually from low levels of exposure over a long period of time.
Nu
merical Health Risk at MCLG
The numerical health risk for Radium-228 based on the PHG is 1 x 10-6. This means one excess cancer case per million people exposed.
B
est Available Technologies and Treatment Costs
The best available technology (BAT) to lower the level of these compounds below the PHG is reverse osmosis. Since the levels are already below the MCL, reverse osmosis would be required to attempt to lower the levels to below the PHG. Please note that accurate cost estimates are difficult, if not impossible, and are highly speculative and theoretical. The estimated annual cost to install and operate reverse osmosis system at 2 of the City’s wells to reduce uranium levels to below the PHG would be approximat ely $5.31 per 1,000 gallons of water treated, which includes annualized cost of construction, plus operation and maintenance costs. This translates into an additional annual cost of approximately $2 33 per service connection per year for the life of the treatment system.
U
ranium
U
ranium is a naturally occurring radioactive element present in geological formations and the earth’s crust. It is introduced into groundwater and surface water through erosion. The MCL for uranium is 20 pCi/L and the PHG for uranium is 0.43 pCi/L.
T
he City collected and analyzed samples for uranium during 2022-2024, with values that ranged from 1.03 pCi/L to 5.80 pCi/L, there were 4 detections above the PHG with an average of 3.93 pCi/L, with all samples below the MCL.
He
alth Risk Category
The category of health risk for uranium is carcinogenicity chronic toxicity (kidneys).
Carcinogenic risk means capable of producing cancer. Chronic toxicity means that adverse effects may develop gradually from low levels of exposure over a long period of time.
Nu
merical Health Risk at MCLG
The numerical health risk for uranium based on the PHG is 1 x 10 -6. This means one excess cancer case per million people exposed.
B
est Available Technologies and Treatment Costs
The best available technology (BAT) to lower the level of these compounds below the PHG is reverse osmosis. Since the levels are already below the MCL, reverse osmosis would be required to attempt to lower the levels to below the PHG. Please note that accurate cost estimates are difficult, if not impossible, and are highly speculative and theoretical. The EXHIBIT 1
estimated annual cost to install and operate reverse osmosis system at 4 of the City’s wells to reduce uranium levels to below the PHG would be approximately $5.31 per 1,000 gallons of water treated, which includes annualized cost of construction, plus operation and maintenance costs. This translates into an additional annual cost of approximately $ 466 per service connection per year for the life of the treatment system.
Total Coliform Bacteria
Total coliform bacteria are tested at sampling sites throughout the City’s water distribution system. No more than 5% of all samples collected in a month can be positive for total coliforms in order to comply with the MCL. Although there is no PHG for total coliform bacteria, the MCLG is 0% positive samples. The reason for the total coliform drinking water standard is to minimize the possibility of the water containing pathogens, which are organisms that cause waterborne diseases. Because total coliform analysis is only a surrogate indicator of the potential 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 anticipated adverse effects on persons would occur,” the USEPA indicates that this is not possible with total coliforms.
Coliform bacteria are an indicator organism that are ubiquitous in nature and are not generally considered harmful. They are used because of the ease in monitoring and analysis. If a positive sample is found, it indicates a potential problem that needs to be investigated and additional sampling is warranted. It is not at all unusual for a system to have an occasional positive coliform bacteria sample. It is difficult, if not impossible; to assure that a system will never get a positive sample.
During 2022, 2023 and 2024, between 145 and 186 samples were collected each month for coliform analyses. Occasionally, a sample(s) is found to be positive for coliform bacteria. Repeat samples for sites having positive coliform bacteria were taken as a follow-up, and in every case, the repeat samples were negative.
The City provides chlorine disinfection to ensure that the water served is microbiologically safe.
The chlorine residual levels are carefully controlled to provide the best health protection without causing the water to have undesirable taste and odor or increasing the level of certain compounds. This careful balance of treatment processes is essential to supplying our customers with safe drinking water.
Other equally important measures that we have implemented include: an effective cross - connection and backflow control programs; an effective monitoring and surveillance program; and maintaining positive pressures in our distribution system. The system has already taken all the steps described by DDW as “Best Available Technology” for coliform bacteria, which is regulated in Title 22, CCR, Section 64447.
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RECOMMENDATIONS FOR FURTHER ACTION
The City of Stockton’s drinking water quality for the contaminants discussed in this 2025 Public Health Goals Report meet all State Water Resources Control Board and USEPA drinking water standards set to protect public health. To further reduce the levels of the contaminants identified in this report that are already significantly below the health-based maximum contaminant levels established to provide “safe drinking water”, additional costly treatment processes at City water wells and DWTP would be required. The effectiveness of the treatment processes to provide any significant reductions in contaminant levels at these already low values is uncertain. The health protection benefits of these further hypothetical reductions are not at all clear and may not be quantifiable. Therefore, no action is proposed at this time.
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1 APPENDIX A
MCLs, DLRs and PHGs for Regulated Drinking Water Contaminants EXHIBIT 1
2025 PHG Triennial Report: Calendar Years 2022-2023-2024 MCLs, DLRs, and PHGs for Regulated Drinking Water Contaminants (Units are in milligrams per liter (mg/L), unless otherwise noted.) Last Update: September 14, 2021
(Reference last update 9/14/2021:
https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/documents/mclreview/mcls_dlrs_phgs.pdf) This table includes:
● DDW's maximum contaminant levels (MCLs)
● DDW's detection limits for purposes of reporting (DLRs) ● Public health goals (PHGs) from the Office of Environmental Health Hazard Assessment (OEHHA) ● PHGs for NDMA and 1,2,3-Trichloropropane (both are unregulated) are at the bottom of this table ● The federal MCLG for chemicals without a PHG, microbial contaminants, and the DLR for 1,2,3-TCP Constituent MCL DLR PHG or (MCLG) Date of PHG
Chemicals with MCLs in 22 CCR §64431 —Inorganic Chemicals Aluminum 1 0.05 0.6 2001
Antimony 0.006 0.006 0.02 1997
Antimony -- -- 0.001 2016
Arsenic 0.010 0.002 0.000004 2004
Asbestos (MFL = million fibers per liter; for fibers
>10 microns long) 7 MFL 0.2 MFL 7 MFL 2003
Barium 1 0.1 2 2003
Beryllium 0.004 0.001 0.001 2003
Cadmium 0.005 0.001 0.00004 2006
Chromium, Total - OEHHA withdrew the 1999
0.0025 mg/L PHG in Nov 2001 0.05 0.01 (0.100) 1999
Chromium, Hexavalent (Chromium-6) 0.01 0.001 0.00002 2011 Cyanide 0.15 0.1 0.15 1997
Fluoride 2 0.1 1 1997
Mercury (inorganic) 0.002 0.001 0.0012 1999 (rev2005)*
Nickel 0.1 0.01 0.012 2001
Nitrate (as N) 10 as N 0.4 45 as NO3
(=10 as N) 2018
Nitrite (as N) 1 as N 0.4 1 as N 2018
Nitrate + Nitrite (as N) 10 as N -- 10 as N 2018
Perchlorate 0.006 0.002 0.001 2015
Selenium 0.05 0.005 0.03 2010
Thallium 0.002 0.001 0.0001 1999 (rev2004)
Copper and Lead, 22 CCR §64672.3
Values referred to as MCLs for lead and copper are not actually MCLs; instead, they are called "Action Levels" under the lead and copper rule
Copper 1.3 0.05 0.3 2008
Lead 0.015 0.005 0.0002 2009
EXHIBIT 1
Constituent MCL DLR PHG or (MCLG) Date of PHG
Radionuclides with MCLs in 22 CCR §64441 and §64443 —Radioactivity [units are picocuries per liter (pCi/L), unless otherwise stated; n/a = not applicable] Gross alpha particle activity - OEHHA concluded
in 2003 that a PHG was not practical 15 3 none n/a
Gross beta particle activity - OEHHA concluded
in 2003 that a PHG was not practical 4 mrem/yr 4 none n/a Radium-226 -- 1 0.05 2006
Radium-228 -- 1 0.019 2006
Radium-226 + Radium-228 5 -- -- --
Strontium-90 8 2 0.35 2006
Tritium 20,000 1,000 400 2006
Uranium 20 1 0.43 2001
Chemicals with MCLs in 22 CCR §64444 —Organic Chemicals (a) Volatile Organic Chemicals (VOCs)
Benzene 0.001 0.0005 0.00015 2001
Carbon tetrachloride 0.0005 0.0005 0.0001 2000
1,2-Dichlorobenzene 0.6 0.0005 0.6 1997 (rev2009)
1,4-Dichlorobenzene (p-DCB) 0.005 0.0005 0.006 1997
1,1-Dichloroethane (1,1-DCA) 0.005 0.0005 0.003 2003
1,2-Dichloroethane (1,2-DCA) 0.0005 0.0005 0.0004 1999 (rev2005) 1,1-Dichloroethylene (1,1-DCE) 0.006 0.0005 0.01 1999
cis-1,2-Dichloroethylene 0.006 0.0005 0.013 2018
trans-1,2-Dichloroethylene 0.01 0.0005 0.05 2018
Dichloromethane (Methylene chloride) 0.005 0.0005 0.004 2000 1,2-Dichloropropane 0.005 0.0005 0.0005 1999
1,3-Dichloropropene 0.0005 0.0005 0.0002 1999 (rev2006) Ethylbenzene 0.3 0.0005 0.3 1997
Methyl tertiary butyl ether (MTBE) 0.013 0.003 0.013 1999 Monochlorobenzene 0.07 0.0005 0.07 2014
Styrene 0.1 0.0005 0.0005 2010
1,1,2,2-Tetrachloroethane 0.001 0.0005 0.0001 2003
Tetrachloroethylene (PCE) 0.005 0.0005 0.00006 2001
Toluene 0.15 0.0005 0.15 1999
1,2,4-Trichlorobenzene 0.005 0.0005 0.005 1999
1,1,1-Trichloroethane (1,1,1-TCA) 0.200 0.0005 1 2006
1,1,2-Trichloroethane (1,1,2-TCA) 0.005 0.0005 0.0003 2006 Trichloroethylene (TCE) 0.005 0.0005 0.0017 2009
Trichlorofluoromethane (Freon 11) 0.15 0.005 1.3 2014
1,1,2-Trichloro-1,2,2-Trifluoroethane (Freon 113) 1.2 0.01 4 1997 (rev2011) Vinyl chloride 0.0005 0.0005 0.00005 2000
Xylenes 1.75 0.0005 1.8 1997
EXHIBIT 1
Constituent MCL DLR PHG or (MCLG) Date of PHG
(b) Non-Volatile Synthetic Organic Chemicals (SOCs)
Alachlor 0.002 0.001 0.004 1997
Atrazine 0.001 0.0005 0.00015 1999
Bentazon 0.018 0.002 0.2 1999 (rev2009)
Benzo(a)pyrene 0.0002 0.0001 0.000007 2010
Carbofuran 0.018 0.005 0.0017 2000
Carbofuran -- -- 0.0007 2016
Chlordane 0.0001 0.0001 0.00003 1997 (rev2006)
Dalapon 0.2 0.01 0.79 1997 (rev2009)
1,2-Dibromo-3-chloropropane (DBCP) 0.0002 0.00001 0.000003 2020 2,4-Dichlorophenoxyacetic acid (2,4-D) 0.07 0.01 0.02 2009 Di(2-ethylhexyl)adipate 0.4 0.005 0.2 2003
Di(2-ethylhexyl)phthalate (DEHP) 0.004 0.003 0.012 1997 Dinoseb 0.007 0.002 0.014 1997 (rev2010)
Diquat 0.02 0.004 0.015 2000
Diquat -- -- 0.006 2016
Endrin 0.002 0.0001 0.0018 1999 (rev2008)
Endrin -- -- 0.0003 2016
Endothal 0.1 0.045 0.094 2014
Ethylene dibromide (EDB) 0.00005 0.00002 0.00001 2003
Glyphosate 0.7 0.025 0.9 2007
Heptachlor 0.00001 0.00001 0.000008 1999
Heptachlor epoxide 0.00001 0.00001 0.000006 1999
Hexachlorobenzene 0.001 0.0005 0.00003 2003
Hexachlorocyclopentadiene 0.05 0.001 0.002 2014
Lindane 0.0002 0.0002 0.000032 1999 (rev2005)
Methoxychlor 0.03 0.01 0.00009 2010
Molinate 0.02 0.002 0.001 2008
Oxamyl 0.05 0.02 0.026 2009
Pentachlorophenol 0.001 0.0002 0.0003 2009
Picloram 0.5 0.001 0.5 1997
Picloram -- -- 0.166 2016
Polychlorinated biphenyls (PCBs) 0.0005 0.0005 0.00009 2007 Simazine 0.004 0.001 0.004 2001
2,4,5-TP (Silvex) 0.05 0.001 0.003 2014
2,3,7,8-TCDD (dioxin) 3x10-8 5x10-9 5x10-11 2010
Thiobencarb 0.07 0.001 0.07 2000
Thiobencarb -- -- 0.042 2016
Toxaphene 0.003 0.001 0.00003 2003
EXHIBIT 1
Constituent MCL DLR PHG or (MCLG) Date of PHG
Chemicals with MCLs in 22 CCR §64533 —Disinfection Byproducts Total Trihalomethanes 0.080 --
Total Trihalomethanes -- -- 0.0008 2010 draft
Bromodichloromethane -- 0.0010 0.00006 2020
Bromoform -- 0.0010 0.0005 2020
Chloroform -- 0.0010 0.0004 2020
Dibromochloromethane -- 0.0010 0.0001 2020
Haloacetic Acids (five) (HAA5) 0.060 -- -- --
Monochloroacetic Acid -- 0.0020 -- --
Dichloroacetic Adic -- 0.0010 -- --
Trichloroacetic Acid -- 0.0010 -- --
Monobromoacetic Acid -- 0.0010 -- --
Dibromoacetic Acid -- 0.0010 -- --
Bromate 0.010 0.0050 or 0.0010a 0.0001 2009
Chlorite 1.0 0.020 0.05 2009
Microbiological Contaminants (TT = Treatment Technique) Coliform % positive samples % 5 (zero)
Cryptosporidium** TT (zero)
Giardia lamblia** TT (zero)
Legionella** TT (zero)
Viruses** TT (zero)
Chemicals with PHGs established in response to DDW requests. These are not currently regulated drinking water contaminants.
N-Nitrosodimethylamine (NDMA) -- -- 0.000003 2006
1,2,3-Trichloropropane -- 0.000005 0.0000007 2009
Notes:
a DDW will maintain a 0.0050 mg/L DLR for bromate to accommodate laboratories that are using EPA Method 300.1. However, laboratories using EPA Methods 317.0 Revision 2.0, 321.8, or 326.0 must meet a 0.0010 mg/L MRL for bromate and should report results with a DLR of 0.0010 mg/L per Federal requirements. *OEHHA's review of this chemical during the year indicated (rev20XX) resulted in no change in the PHG ** Surface water treatment = TT
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1 APPENDIX B
Health Risk Information for Public Health Goal Exceedance Reports EXHIBIT 1
Health Risk Information for Public Health Goal Exceedance Reports
Prepared by
Office of Environmental Health Hazard Assessment
California Environmental Protection Agency
February 2025
NEW for the 2025 Report: New in this document are newly established Public Health Goals (PHGs) for perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and five haloacetic acids: monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid.
Background: Under the Calderon-Sher Safe Drinking Water Act of 1996 (the Act), public water systems with more than 10,000 service connections are required to prepare a report every three years for contaminants that exceed their respective PHGs.1 This document contains health risk information on drinking water contaminants to assist public water systems in preparing these reports. A PHG is the concentration of a contaminant in drinking water that poses no significant health risk if consumed for a lifetime. PHGs are developed and published by the Office of Environmental Health Hazard Assessment (OEHHA) using current risk assessment principles, practices and methods.
2 The water system's report is required to identify the health risk category (e.g., carcinogenicity or neurotoxicity) associated with exposure to each contaminant in drinking water that has a PHG and to include a brief, plainly worded description of these risks. The report is also required to disclose the numerical public health risk, if available, associated with the California Maximum Contaminant Level (MCL) and with the PHG for each contaminant. This health risk information document is prepared by OEHHA every three years to assist the water systems in providing the required information in their reports.
1 Health and Safety Code Section 116470(b)
EXHIBIT 1
2 Health and Safety Code Section 116365
EXHIBIT 1
Numerical health risks: Table 1 presents health risk categories and cancer risk values for chemical contaminants in drinking water that have PHGs.
The Act requires that OEHHA publish PHGs based on health risk assessments using the most current scientific methods. As defined in statute, PHGs for non-carcinogenic chemicals in drinking water are set at a concentration "at which no known or anticipated adverse health effects will occur, with an adequate margin of safety." For carcinogens, PHGs are set at a concentration that "does not pose any significant risk to health." PHGs provide one basis for revising MCLs, along with cost and technological feasibility.
OEHHA has been publishing PHGs since 1997 and the entire list published to date is shown in Table 1.
Table 2 presents health risk information for contaminants that do not have PHGs but have state or federal regulatory standards. The Act requires that, for chemical contaminants with California MCLs that do not yet have PHGs, water utilities use the federal Maximum Contaminant Level Goal (MCLG) for the purpose of complying with the requirement of public notification. MCLGs, like PHGs, are strictly health based and include a margin of safety. One difference, however, is that the MCLGs for carcinogens are set at zero because the US Environmental Protection Agency (US EPA) assumes there is no absolutely safe level of exposure to such chemicals. PHGs, on the other hand, are set at a level considered to pose no significant risk of cancer; this is usually no more than a one-in-one-million excess cancer risk (1x1o-6) level for a lifetime of exposure. In T able 2, the cancer risks shown are based on the US EPA's evaluations.
For more information on health risks: The adverse health effects for each chemical with a PHG are summarized in a PHG technical support document. These documents are available on the OEHHA website (https://oehha.ca.gov/water/public-health-goals- EXHIBIT 1
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Alachlor carcinogenicity
(causes cancer)
0.004 NAs,6 0.002 NA
Aluminum neurotoxicity and
immunotoxicity
(harms the nervous and
immune systems)
0.6 NA 1 NA
Antimony hepatotoxicity
(harms the liver)
0.001 NA 0.006 NA
Arsenic carcinogenicity
(causes cancer)
0.000004
(4x10-6)
1x1o-6
(one per
million)
0.01 2.5x10-3
(2.5 per
thousand)
Asbestos carcinogenicity
(causes cancer)
7 MFL7
(fibers >10
microns in
length)
1x10-5 7 MFL
(fibers >10
microns in
length)
1x1o-6
(one per
million)
Atrazine carcinogenicity
(causes cancer)
0.00015 1x1o-6 0.001 7x1o-6
(seven per
million)
Barium cardiovascular toxicity
(causes high blood
pressure)
2 NA 1 NA
1 Based on the OEHHA PHG technical support document unless otherwise specified. The categories are the hazard traits defined by OEHHA for California's Toxics Information Clearinghouse (online at:
https://oehha.ca.gov/media/downloads/risk-assessment//gcregtext011912.p . 2 mg/L = milligrams per liter of water, equivalent to parts per million (ppm) 3 Cancer Risk = Upper bound estimate of excess cancer risk from lifetime exposure. Actual cancer risk may be lower or zero. 1x10-5 means one excess cancer case per million people exposed. 4 MCL = maximum contaminant level.
5 NA = not applicable. Cancer risk cannot be calculated. 6 The PHG for alachlor is based on a threshold model of carcinogenesis and is set at a level that is believed to be without any significant cancer risk to individuals exposed to the chemical over a lifetime. 7 MFL = million fibers per liter of water.
EXHIBIT 1
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Bentazon hepatotoxicity and
digestive system toxicity
(harms the liver,
intestine, and causes
body weight effects8)
0.2 NA 0.018 NA
Benzene carcinogenicity
(causes leukemia)
0.00015 1x1o-6 0.001 7x1o-6
(seven per
million)
Benzo[a]pyrene carcinogenicity
(causes cancer)
0.000007
(7x1o-6)
1x1o-6 0.0002 3x10-5
(three per
hundred
thousand)
Beryllium digestive system toxicity
(harms the stomach or
intestine)
0.001 NA 0.004 NA
Bromate carcinogenicity
(causes cancer)
0.0001 1x1o-6 0.01 1x10-4
(one per
ten
thousand)
Cadmium nephrotoxicity
(harms the kidney)
0.00004 NA 0.005 NA
Carbofuran reproductive toxicity
(harms the testis)
0.0007 NA 0.018 NA
Carbon
tetrachloride
carcinogenicity
(causes cancer)
0.0001 1x1o-6 0.0005 5x10-5
(five per
million)
8 Body weight effects are an indicator of general toxicity in animal studies.
EXHIBIT 1
Chemical Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Chlordane carcinogenicity
(causes cancer)
0.00003 1x10-5 0.0001 3x10-5
(three per
million)
Chlorite hematotoxicity
(causes anemia)
neurotoxicity
(causes neurobehavioral
effects)
0.05 NA 1 NA
Chromium,
hexavalent
carcinogenicity
(causes cancer)
0.00002 1x1o-6 0.010 5x10-4 (five
per ten
thousand)
Copper digestive system toxicity
(causes nausea,
vomiting, diarrhea)
0.3 NA 1.3 (AL9) NA
Cyanide neurotoxicity
(damages nerves)
endocrine toxicity
(affects the thyroid)
0.15 NA 0.15 NA
Dalapon nephrotoxicity
(harms the kidney)
0.79 NA 0.2 NA
Di(2-ethylhexyl)
adipate (DEHA)
developmental toxicity
(disrupts development)
0.2 NA 0.4 NA
Di(2-ethylhexyl)
phthalate
(DEHP)
carcinogenicity
(causes cancer)
0.012 1x1o-6 0.004 3x10-7
(three per
ten million)
9 AL = action level. The action levels for copper and lead refer to a concentration measured at the tap. Much of the copper and lead in drinking water is derived from household plumbing (The Lead and Copper Rule, Title 22, California Code of Regulations [CCR] section 64672.3).
EXHIBIT 1
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
1,2-Dibromo-3- carcinogenicity
(causes cancer)
0.000003
(3x1o-6)
1x10-5 0.0002 7x10-5
(seven per
hundred
thousand)
chloropropane
(DBCP)
1,2-Dichloro- hepatotoxicity
(harms the liver)
0.6 NA 0.6 NA
benzene
(o-DCB)
1,4-Dichloro- carcinogenicity
(causes cancer)
0.006 1x1o-6 0.005 8x10-7
(eight per
ten million)
benzene
(p-DCB)
1,1-Dichloro- carcinogenicity
(causes cancer)
0.003 1x1o-6 0.005 2x1o-6
(two per
million)
ethane
(1,1-DCA)
1,2-Dichloro- carcinogenicity
(causes cancer)
0.0004 1x10-5 0.0005 1x10-5
(one per
million)
ethane
(1,2-DCA)
1,1-Dichloro- hepatotoxicity
(harms the liver)
0.01 NA 0.006 NA
ethylene
(1,1-DCE)
1,2-Dichloro- nephrotoxicity
(harms the kidney)
0.013 NA 0.006 NA
ethylene, cis
1,2-Dichloro- immunotoxicity
(harms the immune
system)
0.05 NA 0.01 NA
ethylene, trans
Dichloromethane
(methylene
chloride)
carcinogenicity
(causes cancer)
0.004 1x10-5 0.005 1x1o-6
(one per
million)
EXHIBIT 1
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
2,4-Dichloro- hepatotoxicity and
nephrotoxicity
(harms the liver and
kidney)
0.02 NA 0.07 NA
phenoxyacetic
acid (2,4-D)
1 2-Dichloro- 1 carcinogenicity
(causes cancer)
0.0005 1x1o-6 0.005 1x10-5
(one per
hundred
thousand)
propane
(propylene
dichloride)
113-Dichloro- carcinogenicity
(causes cancer)
0.0002 1x1o-6 0.0005 2x1o-6
(two per
million)
propene
(Telone II®)
Dinoseb reproductive toxicity
(harms the uterus and
testis)
0.014 NA 0.007 NA
Diquat ocular toxicity
(harms the eye)
developmental toxicity
(causes malformation)
0.006 NA 0.02 NA
Endothall digestive system toxicity
(harms the stomach or
intestine)
0.094 NA 0.1 NA
Endrin neurotoxicity
(causes convulsions)
hepatotoxicity
(harms the liver)
0.0003 NA 0.002 NA
Ethylbenzene
(phenylethane)
hepatotoxicity
(harms the liver)
0.3 NA 0.3 NA
Ethylene
dibromide (1 )-
carcinogenicity
(causes cancer)
0.00001 1x10-5 0.00005 5x10-5
(five per
million) Dibromoethane)
EXHIBIT 1
Chemical Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Fluoride musculoskeletal toxicity
(causes tooth mottling)
1 NA 2 NA
Glyphosate nephrotoxicity
(harms the kidney)
0.9 NA 0.7 NA
Haloacetic acids:
dibromoacetic
acid
carcinogenicity
(causes cancer)
0.00003 1x1o-6 0.06* 2x10-3
(two per
thousand)10
Haloacetic acids:
dichloroacetic
acid
carcinogenicity
(causes cancer)
0.0002 1x1o-6 0.06* 3x10-4
(three per
ten
thousand)11
Haloacetic acids:
monobromo-
musculoskeletal toxicity
(causes muscular
degeneration)
0.025 NA 0.06* NA
acetic acid
Haloacetic acids:
monochloro-
general toxicity
(causes body and organ
weight changes8)
0.053 NA 0.06* NA
acetic acid
Haloacetic acids:
trichloroacetic
acid
carcinogenicity
(causes cancer)
0.0001 1x1o-6 0.06* 6x10-4
(six per ten
thousand)12
Heptachlor carcinogenicity
(causes cancer)
0.000008
(8x 1o-6)
1x1o-6 0.00001 1x1o-6
(one per
million)
* For total haloacetic acids (the sum of dibromoacetic acid, dichloroacetic acid, monobromoacetic acid, m
onochloroacetic acid, and trichloroacetic acid). There are no MCLs for individual haloacetic acids. 10 Based on 0.060 mg/L dibromoacetic acid; the risk will vary with different combinations and ratios of the o
ther haloacetic acids in a particular sample .
11 Based on 0.060 mg/L dichloroacetic acid; the risk will vary with different combinations and ratios of the o
ther haloacetic acids in a particular sample .
12 Based on 0.060 mg/L trichloroacetic acid; the risk will vary with different combinations and ratios of the o
ther haloacetic acids in a particular sample .
EXHIBIT 1
Chemical Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Heptachlor
epoxide
carcinogenicity
(causes cancer)
0.000006
(6x 1o-6)
1x10-5 0.00001 2x10-5
(two per
million)
Hexachloro- carcinogenicity
(causes cancer)
0.00003 1x1o-6 0.001 3x10-5
(three per
hundred
thousand)
benzene
Hexachloro- digestive system toxicity
(causes stomach
lesions)
0.002 NA 0.05 NA
cyclopentad iene
(HCCPD)
Lead developmental
neurotoxicity
(causes neurobehavioral
effects in children)
cardiovascular toxicity
(causes high blood
pressure)
carcinogenicity
(causes cancer)
0.0002 <1x1o-6
(PHG is
not based
on this
effect)
0.015
(AL9)
2x1o-6
(two per
million)
Lindane
(y-BHC)
carcinogenicity
(causes cancer)
0.000032 1x1o-6 0.0002 6x1o-6
(six per
million)
Mercury
(inorganic)
nephrotoxicity
(harms the kidney)
0.0012 NA 0.002 NA
Methoxychlor endocrine toxicity
(causes hormone
effects)
0.00009 NA 0.03 NA
Meth�I tertiar�- carcinogenicity
(causes cancer)
0.013 1x10-5 0.013 1x10-5
(one per
million)
butyl ether
(MTBE)
EXHIBIT 1
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Molinate carcinogenicity
(causes cancer)
0.001 1x10-5 0.02 2x10-5
(two per
hundred
thousand)
Monochloro- nephrotoxicity
(harms the kidney)
0.07 NA 0.07 NA
benzene
(chlorobenzene)
Nickel developmental toxicity
(causes increased
neonatal deaths)
0.012 NA 0.1 NA
Nitrate hematotoxicity
(causes
methemoglobinemia)
45 as
nitrate
NA 10 as
nitrogen
(=45 as
nitrate)
NA
Nitrite hematotoxicity
(causes
methemoglobinemia)
3 as
nitrite
NA 1 as
nitrogen
(=3 as
nitrite)
NA
Nitrate and
Nitrite
hematotoxicity
(causes
methemoglobinemia)
10 as
nitrogen13
NA 10 as
nitrogen
NA
N-nitroso- carcinogenicity
(causes cancer)
0.000003
(3x1o-6)
1 X 1o-6 none NA
dimethyl-amine
(NOMA)
Oxamyl general toxicity
(causes body weight
effects)
0.026 NA 0.05 NA
13 The joint nitrate/nitrite PHG of 10 mg/L (10 ppm, expressed as nitrogen) does not replace the individual values, and the maximum contribution from nitrite should not exceed 1 mg/L nitrite- nitrogen.
EXHIBIT 1
Chemical Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Pentachloro- carcinogenicity
(causes cancer)
0.0003 1x10-5 0.001 3x10-5
(three per
million)
phenol (PCP)
Perchlorate endocrine toxicity
(affects the thyroid)
developmental toxicity
(causes neurodevelop-
mental deficits)
0.001 NA 0.006 NA
Perfluorooctane
sulfonic acid
(PFOS)
carcinogenicity
(causes cancer)
1x1o-6 1 x1o-6 NA NA
Perfluoro- carcinogenicity
(causes cancer)
7x10-9 1x10-5 NA NA
octanoic acid
(PFOA)
Picloram hepatotoxicity
(harms the liver)
0.166 NA 0.5 NA
Polychlorinated
biphenyls
(PCBs)
carcinogenicity
(causes cancer)
0.00009 1x1o-6 0.0005 6x1o-6
(six per
million)
Radium-226 carcinogenicity
(causes cancer)
0.05 pCi/L 1x1o-6 5 pCi/L
(combined
Ra225+22s)
1x10-4
(one per
ten
thousand)
Radium-228 carcinogenicity
(causes cancer)
0.019 pCi/L 1x1o-6 5 pCi/L
(combined
Ra225+22s)
3x10-4
(three per
ten
thousand)
Selenium integumentary toxicity
(causes hair loss and
nail damage)
0.03 NA 0.05 NA
EXHIBIT 1
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Silvex (2,4,5-TP) hepatotoxicity
(harms the liver)
0.003 NA 0.05 NA
Simazine general toxicity
(causes body weight
effects)
0.004 NA 0.004 NA
Strontium-90 carcinogenicity
(causes cancer)
0.35 pCi/L 1 X 1o-6 8 pCi/L 2x10-5
(two per
hundred
thousand)
Styrene
(vinylbenzene)
carcinogenicity
(causes cancer)
0.0005 1 X 1o-6 0.1 2x10-4
(two per
ten
thousand)
1,1,2,2-
Tetrachloro-
carcinogenicity
(causes cancer)
0.0001 1x10-5 0.001 1x10-5
(one per
hundred
thousand)
ethane
2,3,7,8-Tetra- carcinogenicity
(causes cancer)
5x10-11 1x1o-6 3x1o-8 6x10-4
(six per ten
thousand)
chlorodibenzo-e-
dioxin (TCDD, or
dioxin)
Tetrachloro- carcinogenicity
(causes cancer)
0.00006 1x1o-6 0.005 8x10-5
(eight per
hundred
thousand)
ethylene
(Qerchloro-
ethylene, or
PCE)
Thallium integumentary toxicity
(causes hair loss)
0.0001 NA 0.002 NA
EXHIBIT 1
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Thiobencarb general toxicity
(causes body weight
effects)
hematotoxicity
(affects red blood cells)
0.042 NA 0.07 NA
Toluene
(methylbenzene)
hepatotoxicity
(harms the liver)
endocrine toxicity
(harms the thymus)
0.15 NA 0.15 NA
Toxaphene carcinogenicity
(causes cancer)
0.00003 1x1o-6 0.003 1x10-4
(one per
ten
thousand)
1,2,4-Trichloro- endocrine toxicity
(harms adrenal glands)
0.005 NA 0.005 NA
benzene
1,1,1-Trichloro- neurotoxicity
(harms the nervous
system),
reproductive toxicity
(causes fewer offspring)
hepatotoxicity
(harms the liver)
hematotoxicity
(causes blood effects)
1 NA 0.2 NA
ethane
1,1,2-Trichloro- carcinogenicity
(causes cancer)
0.0003 1x10-5 0.005 2x10-5
(two per
hundred
thousand)
ethane
Trichloro- carcinogenicity
(causes cancer)
0.0017 1x10-5 0.005 3x10-5
(three per
million)
ethylene (TCE)
EXHIBIT 1
Chemical Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Trichlorofluoro- accelerated mortality
(increase in early death)
1.3 NA 0.15 NA
methane
(Freon 11)
1,2,3-Trichloro- carcinogenicity
(causes cancer)
0.0000007
(?x 1o-7)
1x10-5 0.000005
(5x1o-6)
7x1o-6
(seven per
million)
propane
(1,2,3-TCP)
1,1,2-Trichloro- hepatotoxicity
(harms the liver)
4 NA 1.2 NA
1,2,2-trifluoro-
ethane
(Freon 113)
Trihalomethanes:
Bromodichloro-
carcinogenicity
(causes cancer)
0.00006 1x10-5 0.080# 1.3x10-3
(1.3 per
thousand)14 methane
Trihalomethanes:
Bromoform
carcinogenicity
(causes cancer)
0.0005 1x10-5 0.080# 2x10-4
(two per ten
thousand)15
Trihalomethanes:
Chloroform
carcinogenicity
(causes cancer)
0.0004 1x10-5 0.080# 2x10-4
(two per ten
thousand)16
# For total trihalomethanes (the sum of bromodichloromethane, bromoform, chloroform, and dibromochloromethane) . There are no MCLs for individual trihalomethanes . 14 Based on 0.080 mg/L bromodichloromethane; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample .
15 Based on 0.080 mg/L bromoform; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample.
16 Based on 0.080 mg/L chloroform; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample.
EXHIBIT 1
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Trihalomethanes:
Dibromochloro-
carcinogenicity
(causes cancer)
0.0001 1x10-5 0.080# 8x10-4
(eight
per ten
thousand)17
methane
Tritium carcinogenicity
(causes cancer)
400 pCi/L 1x10-5 20,000
pCi/L
5x10-5
(five per
hundred
thousand)
Uranium carcinogenicity
(causes cancer)
0.43 pCi/L 1x1o-6 20 pCi/L 5x10-5
(five per
hundred
thousand)
Vinyl chloride carcinogenicity
(causes cancer)
0.00005 1x1o-6 0.0005 1x10-5
(one per
hundred
thousand)
Xylene neurotoxicity
(affects the senses,
mood, and motor
control)
1.8 (single
isomer or
sum of
isomers)
NA 1.75 (single
isomer or
sum of
isomers)
NA
# For total trihalomethanes (the sum of bromodichloromethane, bromoform, chloroform, and dibromochloromethane) . There are no MCLs for individual trihalomethanes . 17 Based on 0.080 mg/L dibromochloromethane; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample .
EXHIBIT 1
Chemical
Health Risk Category1
US EPA
MCLG2
(mg/L)
Cancer
Risk3
at the
MCLG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
IDisinfection byproducts (DBPs)
Chloramines acute toxicity
(causes irritation)
digestive system toxicity
(harms the stomach)
hematotoxicity
(causes anemia)
45,6 NA7 none NA
Chlorine acute toxicity
(causes irritation)
digestive system toxicity
(harms the stomach)
45,6 NA none NA
Chlorine dioxide hematotoxicity
(causes anemia)
neurotoxicity
(harms the nervous
system)
0.85,6 NA none NA
Radionuclides
1 Health risk category based on the US EPA MCLG document or California MCL document unless otherwise specified.
2 MCLG = maximum contaminant level goal established by US EPA. 3 Cancer Risk = Upper estimate of excess cancer risk from lifetime exposure. Actual cancer risk may be lower or zero. 1x10-5 means one excess cancer case per million people exposed. 4 California MCL = maximum contaminant level established by California. 5 Maximum Residual Disinfectant Level Goal, or MRDLG.
6 The federal Maximum Residual Disinfectant Level (MRDL), or highest level of disinfectant allowed in drinking water, is the same value for this chemical. 7 NA = not available.
EXHIBIT 1
Chemical Health Risk Category1
US EPA
MCLG2
(mg/L)
Cancer
Risk3
at the
MCLG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Gross alpha
particles8
carcinogenicity
(causes cancer)
0 (21op0
included)
0 15 pCi/L9
(includes
radium but
not radon
and
uranium)
upto1x1O-3
(for 210Po,
the most
potent alpha
emitter)
Beta particles
and photon
emitters8
carcinogenicity
(causes cancer)
o (21opb
included)
0 50 pCi/L
Uudged
equiv. to 4
mrem/yr)
up to 2x1O-3
(for 210Pb,
the most
potent beta-
emitter)
8 MCLs for gross alpha and beta particles are screening standards for a group of radionuclides. Corresponding PHGs were not developed for gross alpha and beta particles. See the OEHHA memoranda discussing the cancer risks at these MCLs at http://www.oehha.ca.gov/water/reports/grossab.html.
9 pCi/L = picocuries per liter of water.
EXHIBIT 1
1 APPENDIX C
Cost Estimates for Treatment for Treatment Technologies Source – Association of California Water Agencies – Suggested Guidelines for Preparation of Required Reports dated April 2022
EXHIBIT 1
ATTACHMENT NO. 3
1 Ion Exchange Coachella Valley WD, for GW, to reduce Arsenic concentrations. 2011 costs.
2.68 2 Ion Exchange City of Riverside Public Utilities, for GW, for Perchlorate treatment.
1.30 3 Ion Exchange Carollo Engineers, anonymous utility, 2012 costs for treating GW source for Nitrates. Design sauce waterconcentration:
88 mg/L NO3 Design finished water concentration: 45 mg/L NO3. Does not include concentrate disposal or land cost.
0.98 4 Granular Activated
Carbon
City of Riverside Public Utilities, GW sources, for TCE,DBCP (VOC, SOC) treatment.
0.65 5 Granular Activated
Carbon
Carollo Engineers, anonymous utility, 2012 costs for treating SW source for TTHMs. Design sauce water concentration:
0.135 mg/L. Design finished water concentration: 0.07
mg/L. Does not include concentrate disposal or land cost.
0.47 6 Granular Activated
Carbon, Liquid
Phase
LADWP, Liquid Phase GAC treatment atTujunga Wellfield.
Costs for treating 2 wells. Treament for 1,1 DCE (VOC). 2011-2012 costs.
1.99 7 Reverse Osmosis Carollo Engineers, anonymous utility, 2012 costs for treating GW source for Nitrates. Design sauce waterconcentration:
88 mg/L NO3 Design finished water concentration: 45 mg/L NO3. Does not include concentrate disposal or land cost.
1.05 8 Packed Tower
Aeration
City of Monrovia, treatment to reduce TCE, PCE
concentrations. 2011-12 costs.
0.58 9 Ozonation+
Chemical addition
SCVWD, STWTP treatment plant includes chemical
addition+ ozone generation costs to reduce THM/HAAs
concentrations. 2009-2012 costs.
0.12 10 Ozonation+
Chemical addition
SCVWD, PWTP treatment plant includes chemical
addition+ ozone generation costs to reduce THM/HAAs
concentrations, 2009-2012 costs.
0.26 11 Coagulation/
Filtration
Soquel WD, treatment to reduce manganeseconcentrations
in GW. 2011 costs.
0.98 12 Coagulation/
Filtration
Optimization
San Diego WA, costs to reduce THM/Bromate, Turbidity
concentrations, raw SW a blend of State Water Project water and Colorado River water, treated at Twin Oaks Valley WTP.
1.12 13 Blending (Well) Rancho California WD, GW blending well, 1150 gpm, to reduce fluoride concentrations.
0.93 14 Blending (Wells) Rancho California WD, GW blending wells, to reducearsenic concentrations, 2012 costs.
0.76 15 Blending Rancho California WD, using MWD water to blend with GW to reduce arsenic concentrations. 2012 costs.
0.91 16 Corrosionlnhibition Atascadero Mutual WC, corrosion inhibitor addition to control aggressive water. 2011 costs.
0.11 * Costs were adjusted from date of original estimates to present using the Engineering News Record (ENR) 20-City average Construction Cost Index of 13,571 for 2024.
EXHIBIT 1
1 Reduction -
Coagulation -
Filtration
February 28, 2013, Final Report Chromium Removal
Research, City of Glendale,CA. 100-2000 gpm. Reduce
Hexavalent Chromium to 1 ppb.
2.14 - 13.38
2 IX - Weak Base
Anion Resin
February 28, 2013, Final Report Chromium Removal
Research, City of Glendale,CA. 100-2000 gpm. Reduce
Hexavalent Chromium to 1 ppb.
2.19-9.16
3 IX Golden State Water Co., IX w/disposable resin, 1MGD, Perchlorate removal, built in 2010.
0.67 4 IX Golden State Water Co., IX w/disposable resin, 1000 gpm, perchlorate removal (Proposed; O&M estimated).
1.47 5 IX Golden State Water Co., IX with brine regeneration, 500 gpm for Selenium removal, builtin 2007.
9.59 6 GFO/Adsorption Golden State Water Co., Granular Ferric Oxide Resin, Arsenic removal, 600 gpm, 2 facilities, builtin 2006.
2.51-2.67
7 RO Inland Empire Utilities Agency: ChinoBasin Desalter. RO cost to reduce 800 ppm TDS, 150 ppm Nitrate (as NO3);
approx. 7 mgd.
3.28 8 IX Inland Empire Utilities Agency: ChinoBasin Desalter. IX cost to reduce 150 ppm Nitrate (as NO3); approx. 2.6 mgd.
1.82 9 Packed Tower
Aeration
Inland Empire Utilities Agency: ChinoBasin Desalter. PTA- VOC air stripping, typical treated flow of approx. 1.6 mgd.
0.55 10 IX West Valley WD Report, for WaterRecycling Funding Program, for 2.88 mgd treatment facility. IX to remove
Perchlorate, Perchlorate levels 6-10 ppb. 2008 costs.
0.76 - 1.08
11 Coagulation
Filtration
West Valley WD, includes capital, O&M costs for 2.88 mgd treatment facility - Layne Christensen packaged coagulation Arsenic removal system. 2009-2012 costs.
0.50 12 FBR West Valley WD/Envirogen design data for the O&M + actual capitol costs, 2.88 mgdfluidized bed reactor (FBR) treatment system, Perchlorate and Nitrate removal, followed by multimedia filtration & chlorination, 2012. NOTE: The capitol cost for the treatment facility for the first 2,000 gpm is $23 million annualized over 20 years with ability to expand to 4,000 gpm with minimal costs in the future. $17 million funded through state and federal grants with the remainder funded by WVWD and the City of Rialto.
2.26 - 2.38
* Costs were adjusted from date of original estimates to present using the Engineering News Record (ENR) 20-City average Construction Cost Index of 13,571 for 2024.
EXHIBIT 1
Granular Activated
Carbon
Malcolm Pirnie estimate for California Urban Water
Agencies, large surface water treatment plants treating water from the State Water Project to meet Stage 2 D/DBP and bromate regulation, 1998
0.77-1.47
2 Granular Activated
Carbon
Carollo Engineers, estimate for VOC treatment (PCE), 95% removal of PCE, Oct . 1994,1900 gpm design capacity
0.36 3 Granular Activated
Carbon
Carollo Engineers, est. for a large No. Calif. surf. water treatment plant ( 90 mgd capacity) treating water from the State Water Project, to reduce THM precursors, ENR
construction cost index= 6262 (San Francisco area)- 1992
1.69 4 Granular Activated
Carbon
CH2M Hill study on San Gabriel Basin, for135 mgd central treatment facility for VOC and SOC removal by GAC, 1990
0.66 - 0.96
5 Granular Activated
Carbon
Southern California Water Co. - actual data for "rented" GAC to remove VOCs (1,1- DCE), 1.5 mgd capacity facility, 1998
3.03 6 Granular Activated
Carbon
Southern California Water Co. - actual data for permanent GAC to remove VOCs (TCE), 2.16 mgd plant capacity, 1998
1.96 7 Reverse Osmosis Malcolm Pirnie estimate for California Urban Water Agencies, large surface water treatment plants treating water from the State Water Project to meet Stage 2 D/DBP and bromate regulation, 1998
2.28 - 4.35
8 Reverse Osmosis Boyle Engineering, RO cost to reduce 1000 ppm TDS in brackish groundwater in So. Calif., 1.0 mgd plant operated at 40% of design flow, high brine line cost, May 1991
5.37 9 Reverse Osmosis Boyle Engineering, RO cost to reduce 1000 ppm TDS in brackish groundwater in So. Calif., 1.0 mgd plant operated at 100% of design flow, high brine line cost, May 1991
3.31 10 Reverse Osmosis Boyle Engineering, RO cost to reduce 1000 ppm TDS in brackish groundwater in So. Calif., 10.0 mgd plant operated at 40% of design flow, high brine line cost, May 1991
3.58 11 Reverse Osmosis Boyle Engineering, RO cost to reduce 1000 ppm TDS in brackish groundwater in So. Calif., 10.0 mgd plant operated at 100% of design flow, high brine line cost, May 1991
2.77 12 Reverse Osmosis Arsenic Removal Study, City of Scottsdale, AZ - CH2M Hill, for a 1.0 mgd plant operated at 40% of design capacity, Oct. 1991
8.99 13 Reverse Osmosis Arsenic Removal Study, City of Scottsdale, AZ - CH2M Hill, for a 1.0 mgd plant operated at 100% of design capacity, Oct. 1991
5.31 14 Reverse Osmosis Arsenic Removal Study, City of Scottsdale, AZ - CH2M Hill, for a 10.0 mgd plant operated at 40% of design capacity, Oct. 1991
3.97 * Costs were adjusted from date of original estimates to present using the Engineering News Record (ENR) 20-City average Construction Cost Index of 13,571 for 2024.
EXHIBIT 1
15 Reverse Osmosis Arsenic Removal Study, City of Scottsdale, AZ - CH2M Hill, for a 10.0 mgd plant operated at 100% of design capacity, Oct. 1991
2.46 16 Reverse Osmosis CH2M Hill study on San Gabriel Basin, for135 mgd central treatment facility with RO to remove nitrate, 1990
2.48 - 4.35
17 Packed Tower
Aeration
Analysis of Costs for Radon Removal... (AWWARF
publication), Kennedy/Jenks, for a 1.4 mgd facility operating at 40% of design capacity, Oct. 1991
1.42 18 Packed Tower
Aeration
Analysis of Costs for Radon Removal... (AWWARF
publication), Kennedy/Jenks, for a 14.0 mgd facility
operating at 40% of design capacity, Oct. 1991
0.76 19 Packed Tower
Aeration
Carollo Engineers, estimate for VOC treatment (PCE) by
packed tower aeration, without off-gas treatment, O&M
costs based on operation during 329 days/year at 10%
downtime, 16 hr/day air strippingoperation, 1900 gpm
design capacity, Oct. 1994
0.38 20 Packed Tower
Aeration
Carollo Engineers, for PCE treatment by Ecolo-Flo Enviro- Tower air stripping, without off -gas treatment, O&M costs based on operation during 329 days/year at 10% downtime, 16 hr/day air stripping operation, 1900 gpm design
capacity, Oct. 1994
0.39 21 Packed Tower
Aeration
CH2M Hill study on San Gabriel Basin, for135 mgd central treatment facility - packed tower aeration for VOC and
radon removal, 1990
0.63 - 1.01
22 Advanced
Oxidation
Processes
Carollo Engineers, estimate for VOC treatment (PCE) by UV Light, Ozone, Hydrogen Peroxide, O&M costs based on operation during 329 days/year at 10% downtime, 24 hr/day AOP operation, 1900 gpm capacity, Oct. 1994
0.75 23 Ozonation Malcolm Pirnie estimate for CUWA, large surface water treatment plants using ozone to treat water from the
State Water Project to meet Stage 2 D/DBP and bro mate
regulation, Cryptosporidium inactivation requirements, 1998
0.17 - 0.36
24 Ion Exchange CH2M Hill study on San Gabriel Basin, for 135 mgd central treatment facility - ion exchange to remove nitrate, 1990
0.82 - 1.08
* Costs were adjusted from date of original estimates to present using the Engineering News Record (ENR) 20-City average Construction Cost Index of 13,571 for 2024
EXHIBIT 1