Report on Water Quality
Relative
to Public Health
Goals
June 2022
CITY OF STOCKTON
Q ,
MUNICIPAL UTILITIES DEPARTMENT
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2 TABLE OF CONTENTS
SECTION 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
3 CITY OF STOCKTON WATER SYSTEM
REPORT ON WATER QUALITY
RELATIVE TO PUBLIC HEALTH GOALS
June 2022
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, 2022 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.
This 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 2019 and 2021 at a level exceeding a PHG or MCLG:
• Numerical 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.
PUBLIC 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 pub lic 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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4 CITY OF STOCKTON WATER SOURCES
Most of the City’s drinking water is treated surface water produce d 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.
WATER QUALITY DATA CONSIDERED
All water quality data collected from the City’s treated surface water and groundwater between 2019 and 2021 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 201 9, 20 20, and 20 21 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:
http://www.stocktonca.gov/files/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.
PHGs, 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 t he 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 Rep orting) 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
5 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 natural ly 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 2019, 2020 and 2021, nine (9) samples were collected from a total of nine (9) active well sites. Arsenic values ranged fr om 0 µg/L to a maximum of 6.7 µg/L, with an average concentration of 4.3 µg/L over the three-year span. The MCL is 10 µg/L on a quarterly running average.
Three (3) samples were collected from the SEWD treated surface water and there were 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 r isk 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 2019 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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6 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 $0.73 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 $221 per service connection per year for the life of the treatment system.
Bromate
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.
In sampling conducted at the DWTP from 2019 to 2021, a total of thirty five (35) samples were collected and bromate was detected in seven of those samples. Bromate values ranged from 0 µg/L to 28 µg/L with an average of 2.8 µg/L over the three-year span. The City is complying of the MCL, as the quarterly running average is below 10 µg/L.
Health Risk Category
The health risk category for bromate is carcinogenicity. People who drink water containi ng bromate above the MCL throughout their lifetime could experience an increased risk of getting cancer.
Numerical 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.
Best 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 reduc e bromate levels to below the PHG would be approximately $0. 69 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 $156 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 natura lly occurring radionuclides are alpha particle emitters.
Contamination by man-made nuclear materials can also occur. The man -made radionuclides, EXHIBIT 1
7 which are primarily beta and photon emitters, are produced by several activities that involve 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 groundwa ter 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 201 9-2021, with values that ranged from non-detect (ND) to 7.11 pCi/L, with an average value of 4.51 pCi/L, all sample results were below the MCL.
Health Risk Category
The category of health risk for gross alpha particles is carcinogenic ity 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 t he 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 opera te reverse osmosis system at 13 of the City’s wells to reduce uranium levels to below the PHG would be approximately $4.75 per 1,000 gallons of water treated, which includes annualized cost of construction, plus operation and maintenance costs. This transl ates into an additional annual cost of approximately $1351 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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8 The City collected and analyzed samples for Radium-228 during 2019-2021, with values that ranged from ND to 1.71 pCi/L, with an average result of 0.60 pCi/L, with all samples below the MCL.
Health 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.
Numerical 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.
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 2 of the City’s wells to reduce uranium levels to below the PHG would be approximately $ 4.75 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 $208 per service connection per year for the life of the treatment system.
Uranium
Uranium 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.
The City collected and analyzed samples for uranium during 201 9-2021, with values that ranged from ND to 5.80 pCi/L, there were 4 detections above the PHG with an average of 3.71 pCi/L, with all samples below the MCL.
Health Risk Category
The category of hea lth 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.
Numerical 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.
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 accu rate cost EXHIBIT 1
9 estimates are difficult, if not impossible, and are highly speculative and theoretical. The 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 approximat ely $4.75 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 $416 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 tha t 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 2019, 2020 and 2021, 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 process es 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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10 RECOMMENDATIONS FOR FURTHER ACTION
The City of Stockton’s drinking water quality for the contaminants discussed in this 2022 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 r eductions are not at all clear and may not be quantifiable. Therefore, no action is proposed at this time.
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11 APPENDIX A
MCLs, DLRs and PHGs for Regulated Drinking Water Contaminants
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ATTACHMENT NO. 1
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2022 PHG Triennial Report: Calendar Years 2019-2020-2021 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
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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
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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
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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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12 APPENDIX B
Health Risk Information for Public Health Goal Exceedance Reports
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Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 1
Health Risk Information for
Public Health Goal Exceedance Reports
Prepared by
Office of Environmental Health Hazard Assessment
California Environmental Protection Agency
February 2022
NEW for the 2022 Report: New in this document are an updated Public Health Goal (PHG) for 1,2-dibromo-3-chloropropane (DBCP) and newly established PHGs for the trihalomethanes bromodichloromethane, bromoform, chloroform, and dibromochloromethane.
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 i s 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)
2 Health and Safety Code Section 116365
EXHIBIT 1
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 2
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 b ut 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 (1 10-6) level for a lifetime of exposure. In Table 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- phgs).
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 3
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 NA5,6 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
(4×10-6)
110-6
(one per
million)
0.01 2.510-3
(2.5 per
thousand)
Asbestos carcinogenicity
(causes cancer)
7 MFL7
(fibers >10
microns in
length)
110-6 7 MFL
(fibers >10
microns in
length)
110-6
(one per
million)
Atrazine carcinogenicity
(causes cancer)
0.00015 110-6 0.001 710-6
(seven per
million)
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.pdf). 2 mg/L = milligrams per liter of water or 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. 110-6 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
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 4
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Barium cardiovascular toxicity
(causes high blood
pressure)
2 NA 1 NA
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 110-6 0.001 710-6
(seven per
million)
Benzo[a]pyrene carcinogenicity
(causes cancer)
0.000007
(710-6)
110-6 0.0002 310-5
(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 110-6 0.01 110-4
(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
8 Body weight effects are an indicator of general toxicity in animal studies.
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 5
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Carbon
tetrachloride
carcinogenicity
(causes cancer)
0.0001 110-6 0.0005 510-6
(five per
million)
Chlordane carcinogenicity
(causes cancer)
0.00003 110-6 0.0001 310-6
(three per
million)
Chlorite hematotoxicity
(causes anemia)
neurotoxicity
(causes neurobehavioral
effects)
0.05 NA 1 NA
Chromium,
hexavalent
carcinogenicity
(causes cancer)
0.00002 110-6 none NA
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
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
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 6
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Di(2-ethylhexyl)
phthalate
(DEHP)
carcinogenicity
(causes cancer)
0.012 110-6 0.004 310-7
(three per
ten million)
1,2-Dibromo-3-
chloropropane
(DBCP)
carcinogenicity
(causes cancer)
0.000003
(3x10-6)
110-6 0.0002 710-5
(seven per
hundred
thousand)
1,2-Dichloro-
benzene
(o-DCB)
hepatotoxicity
(harms the liver)
0.6 NA 0.6 NA
1,4-Dichloro-
benzene
(p-DCB)
carcinogenicity
(causes cancer)
0.006 110-6 0.005 810-7
(eight per
ten million)
1,1-Dichloro-
ethane
(1,1-DCA)
carcinogenicity
(causes cancer)
0.003 110-6 0.005 210-6
(two per
million)
1,2-Dichloro-
ethane
(1,2-DCA)
carcinogenicity
(causes cancer)
0.0004 110-6 0.0005 110-6
(one per
million)
1,1-Dichloro-
ethylene
(1,1-DCE)
hepatotoxicity
(harms the liver)
0.01 NA 0.006 NA
1,2-Dichloro-
ethylene, cis
nephrotoxicity
(harms the kidney)
0.013 NA 0.006 NA
1,2-Dichloro-
ethylene, trans
immunotoxicity
(harms the immune
system)
0.05 NA 0.01 NA
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 7
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Dichloromethane
(methylene
chloride)
carcinogenicity
(causes cancer)
0.004 110-6 0.005 110-6
(one per
million)
2,4-Dichloro-
phenoxyacetic
acid (2,4-D)
hepatotoxicity and
nephrotoxicity
(harms the liver and
kidney)
0.02 NA 0.07 NA
1,2-Dichloro-
propane
(propylene
dichloride)
carcinogenicity
(causes cancer)
0.0005 110-6 0.005 110-5
(one per
hundred
thousand)
1,3-Dichloro-
propene
(Telone II)
carcinogenicity
(causes cancer)
0.0002 110-6 0.0005 210-6
(two per
million)
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
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 8
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Ethylene
dibromide (1,2-
Dibromoethane)
carcinogenicity
(causes cancer)
0.00001 110-6 0.00005 510-6
(five per
million)
Fluoride musculoskeletal toxicity
(causes tooth mottling)
1 NA 2 NA
Glyphosate nephrotoxicity
(harms the kidney)
0.9 NA 0.7 NA
Heptachlor carcinogenicity
(causes cancer)
0.000008
(8×10-6)
110-6 0.00001 110-6
(one per
million)
Heptachlor
epoxide
carcinogenicity
(causes cancer)
0.000006
(6×10-6) 110-6 0.00001 210-6
(two per
million)
Hexachloroben-
zene
carcinogenicity
(causes cancer)
0.00003 110-6 0.001 310-5
(three per
hundred
thousand)
Hexachloro-
cyclopentadiene
(HCCPD)
digestive system toxicity
(causes stomach
lesions)
0.002 NA 0.05 NA
Lead developmental
neurotoxicity
(causes neurobehavioral
effects in children)
cardiovascular toxicity
(causes high blood
pressure)
carcinogenicity
(causes cancer)
0.0002 <110-6
(PHG is
not based
on this
effect)
0.015
(AL9)
210-6
(two per
million)
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 9
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Lindane
(-BHC)
carcinogenicity
(causes cancer)
0.000032 110-6 0.0002 610-6
(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
Methyl tertiary-
butyl ether
(MTBE)
carcinogenicity
(causes cancer)
0.013 110-6 0.013 110-6
(one per
million)
Molinate carcinogenicity
(causes cancer)
0.001 110-6 0.02 210-5
(two per
hundred
thousand)
Monochloro-
benzene
(chlorobenzene)
nephrotoxicity
(harms the kidney)
0.07 NA 0.07 NA
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
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 10
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Nitrate and
Nitrite
hematotoxicity
(causes
methemoglobinemia)
10 as
nitrogen10
NA 10 as
nitrogen
NA
N-nitroso-
dimethyl-amine
(NDMA)
carcinogenicity
(causes cancer)
0.000003
(310-6)
1×10-6 none NA
Oxamyl general toxicity
(causes body weight
effects)
0.026 NA 0.05 NA
Pentachloro-
phenol (PCP)
carcinogenicity
(causes cancer)
0.0003 110-6 0.001 310-6
(three per
million)
Perchlorate endocrine toxicity
(affects the thyroid)
developmental toxicity
(causes neurodevelop-
mental deficits)
0.001 NA 0.006 NA
Picloram hepatotoxicity
(harms the liver)
0.166 NA 0.5 NA
Polychlorinated
biphenyls
(PCBs)
carcinogenicity
(causes cancer)
0.00009 110-6 0.0005 610-6
(six per
million)
Radium-226 carcinogenicity
(causes cancer)
0.05 pCi/L 110-6 5 pCi/L
(combined
Ra226+228)
110-4
(one per
ten
thousand)
10 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
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 11
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Radium-228 carcinogenicity
(causes cancer)
0.019 pCi/L 110-6 5 pCi/L
(combined
Ra226+228)
310-4
(three per
ten
thousand)
Selenium integumentary toxicity
(causes hair loss and
nail damage)
0.03 NA 0.05 NA
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 1×10-6 8 pCi/L 210-5
(two per
hundred
thousand)
Styrene
(vinylbenzene)
carcinogenicity
(causes cancer)
0.0005 1×10-6 0.1 210-4
(two per
ten
thousand)
1,1,2,2-
Tetrachloro-
ethane
carcinogenicity
(causes cancer)
0.0001 110-6 0.001 110-5
(one per
hundred
thousand)
2,3,7,8-Tetra-
chlorodibenzo-p-
dioxin (TCDD, or
dioxin)
carcinogenicity
(causes cancer) 510-11 110-6 310-8 610-4
(six per ten
thousand)
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 12
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Tetrachloro-
ethylene
(perchloro-
ethylene, or
PCE)
carcinogenicity
(causes cancer)
0.00006 110-6 0.005 810-5
(eight per
hundred
thousand)
Thallium integumentary toxicity
(causes hair loss)
0.0001 NA 0.002 NA
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 110-6 0.003 110-4
(one per
ten
thousand)
1,2,4-Trichloro-
benzene
endocrine toxicity
(harms adrenal glands)
0.005 NA 0.005 NA
1,1,1-Trichloro-
ethane
neurotoxicity
(harms the nervous
system),
reproductive toxicity
(causes fewer offspring)
hepatotoxicity
(harms the liver)
hematotoxicity
(causes blood effects)
1 NA 0.2 NA
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 13
Chemical
Health Risk Category1
California
PHG
(mg/L)2
Cancer
Risk3
at the
PHG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
1,1,2-Trichloro-
ethane
carcinogenicity
(causes cancer)
0.0003 1x10-6 0.005 210-5
(two per
hundred
thousand)
Trichloro-
ethylene (TCE)
carcinogenicity
(causes cancer)
0.0017 110-6 0.005 310-6
(three per
million)
Trichlorofluoro-
methane
(Freon 11)
accelerated mortality
(increase in early death)
1.3 NA 0.15 NA
1,2,3-Trichloro-
propane
(1,2,3-TCP)
carcinogenicity
(causes cancer)
0.0000007
(7×10-7)
1x10-6 0.000005
(5×10-6)
710-6
(seven per
million)
1,1,2-Trichloro-
1,2,2-trifluoro-
ethane
(Freon 113)
hepatotoxicity
(harms the liver)
4 NA 1.2 NA
Trihalomethanes:
Bromodichloro-
methane
carcinogenicity
(causes cancer)
0.00006 1x10-6 0.080* 1.310-3
(1.3 per
thousand)11
Trihalomethanes:
Bromoform
carcinogenicity
(causes cancer)
0.0005 1x10-6 0.080* 210-4
(two per ten
thousand)12
* For total trihalomethanes (the sum of bromodichloromethane, bromoform, chloroform, and dibromochloromethane). There are no MCLs for individual trihalomethanes. 11 Based on 0.080 mg/L bromodichloromethane; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample.
12 Based on 0.080 mg/L bromoform; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample.
EXHIBIT 1
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 14
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:
Chloroform
carcinogenicity
(causes cancer)
0.0004 1x10-6 0.080* 210-4
(two per ten
thousand)13
Trihalomethanes:
Dibromochloro-
methane
carcinogenicity
(causes cancer)
0.0001 1x10-6 0.080* 810-4
(eight
per ten
thousand)14
Tritium carcinogenicity
(causes cancer)
400 pCi/L 1x10-6 20,000
pCi/L
510-5
(five per
hundred
thousand)
Uranium carcinogenicity
(causes cancer)
0.43 pCi/L 110-6 20 pCi/L 510-5
(five per
hundred
thousand)
Vinyl chloride carcinogenicity
(causes cancer)
0.00005 110-6 0.0005 110-5
(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. 13 Based on 0.080 mg/L chloroform; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample.
14 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
Table 2: Health Risk Categories and Cancer Risk Values for Chemicals without California Public Health Goals
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 15
Chemical
Health Risk Category1
US EPA
MCLG2
(mg/L)
Cancer
Risk3
at the
MCLG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Disinfection 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
Disinfection byproducts: haloacetic acids (HAA5)
Monochloroacetic
acid (MCA)
general toxicity
(causes body and organ
weight changes8)
0.07 NA none NA
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. 110-6 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.
8 Body weight effects are an indicator of general toxicity in animal studies.
EXHIBIT 1
Table 2: Health Risk Categories and Cancer Risk Values for Chemicals without California Public Health Goals
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 16
Chemical
Health Risk Category1
US EPA
MCLG2
(mg/L)
Cancer
Risk3
at the
MCLG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Dichloroacetic
acid (DCA)
Carcinogenicity
(causes cancer)
0 0 none NA
Trichloroacetic
acid (TCA)
hepatotoxicity
(harms the liver)
0.02 NA none NA
Monobromoacetic
acid (MBA)
NA none NA none NA
Dibromoacetic
acid (DBA)
NA none NA none NA
Total haloacetic
acids (sum of
MCA, DCA, TCA,
MBA, and DBA)
general toxicity,
hepatotoxicity and
carcinogenicity
(causes body and organ
weight changes, harms
the liver and causes
cancer)
none NA 0.06 NA
Radionuclides
Gross alpha
particles9
carcinogenicity
(causes cancer)
0 (210Po
included)
0 15 pCi/L10
(includes
radium but
not radon
and
uranium)
up to 1x10-3
(for 210Po,
the most
potent alpha
emitter)
9 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.
10 pCi/L = picocuries per liter of water.
EXHIBIT 1
Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2019
Table 2: Health Risk Categories and Cancer Risk Values for Chemicals without California Public Health Goals
Chemical
Health Risk Category1
US EPA
MCLG2
(mg/L)
Cancer
Risk3
at the
MCLG
California
MCL4
(mg/L)
Cancer
Risk at the
California
MCL
Beta particles
and photon
emitters9
carcinogenicity
(causes cancer)
0 (210Pb
included)
0 50 pCi/L
(judged
equiv. to 4
mrem/yr)
up to 2x10-3
(for 210Pb,
the most
potent beta-
emitter)
EXHIBIT 1
13 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
40 ATTACHMENT NO. 3
Table 3
Reference: Updated 2012 ACWA Cost of Treatment Table
COST ESTIMATES FOR TREATMENT TECHNOLOGIES
(INCLUDES ANNUALIZED CAPITAL AND O&M COSTS)
No. Treatment
Technology
Source of Information
Estimated 2012 Unit
Cost Indexed to 2021*
($/1,000 gallons treated)
1 Granular Activated
Carbon
Reference: 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
0.69 - 1.31
2 Granular Activated
Carbon
Reference: Carollo Engineers, estimate for VOC
treatment (PCE), 95% removal of PCE, Oct. 1994,1900
gpm design capacity
0.32 3
Granular Activated
Carbon
Reference: 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
1.51 4
Granular Activated
Carbon
Reference: CH2M Hill study on San Gabriel Basin, for
135 mgd central treatment facility for VOC and SOC
removal by GAC, 1990
0.59 - 0.86
5 Granular Activated
Carbon
Reference: Southern California Water Co. - actual data
for "rented" GAC to remove VOCs (1,1-DCE), 1.5 mgd
capacity facility, 1998
2.71 6
Granular Activated
Carbon
Reference: Southern California Water Co. - actual data
for permanent GAC to remove VOCs (TCE), 2.16 mgd
plant capacity, 1998
1.75 7
Reverse Osmosis
Reference: 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
2.036 –
3.89 8
Reverse Osmosis
Reference: 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
4.80 9
Reverse Osmosis
Reference: 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
2.96 10
Reverse Osmosis
Reference: 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
3.20 EXHIBIT 1
COST ESTIMATES FOR TREATMENT TECHNOLOGIES
(INCLUDES ANNUALIZED CAPITAL AND O&M COSTS)
40 No. Treatment
Technology
Source of Information
Estimated 2012 Unit
Cost Indexed to 2021*
($/1,000 gallons treated)
11 Reverse Osmosis
Reference: 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
2.48 12
Reverse Osmosis
Reference: Arsenic Removal Study, City of Scottsdale,
AZ - CH2M Hill, for a 1.0 mgd plant operated at 40% of
design capacity, Oct. 1991
8.04 13
Reverse Osmosis
Reference: Arsenic Removal Study, City of Scottsdale,
AZ - CH2M Hill, for a 1.0 mgd plant operated at 100% of design capacity, Oct. 1991
4.75 14
Reverse Osmosis
Reference: Arsenic Removal Study, City of Scottsdale,
AZ - CH2M Hill, for a 10.0 mgd plant operated at 40% of design capacity, Oct. 1991
3.55 15
Reverse Osmosis
Reference: Arsenic Removal Study, City of Scottsdale,
AZ - CH2M Hill, for a 10.0 mgd plant operated at 100%
of design capacity, Oct. 1991
2.20 16
Reverse Osmosis
Reference: CH2M Hill study on San Gabriel Basin, for
135 mgd central treatment facility with RO to remove
nitrate, 1990
2.22 - 3.89
17 Packed Tower
Aeration
Reference: Analysis of Costs for Radon Removal...
(AWWARF publication), Kennedy/Jenks, for a 1.4 mgd
facility operating at 40% of design capacity, Oct. 1991
1.27 18
Packed Tower
Aeration
Reference: Analysis of Costs for Radon Removal...
(AWWARF publication), Kennedy/Jenks, for a 14.0 mgd
facility operating at 40% of design capacity, Oct. 1991
0.68 19
Packed Tower
Aeration
Reference: 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 stripping
operation, 1900 gpm design capacity, Oct. 1994
0.34 20
Packed Tower
Aeration
Reference: 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
0.35 21
Packed Tower
Aeration
Reference: CH2M Hill study on San Gabriel Basin, for
135 mgd central treatment facility - packed tower
aeration for VOC and radon removal, 1990
0.55 - 0.90
EXHIBIT 1
COST ESTIMATES FOR TREATMENT TECHNOLOGIES
(INCLUDES ANNUALIZED CAPITAL AND O&M COSTS)
40 * Costs were adjusted from date of original estimates to present, where appropriate, using the Engineering News Record (ENR) annual average Construction Cost Index of 12,133 for 2021.
No. Treatment
Technology
Source of Information
Estimated 2012 Unit
Cost Indexed to 2021*
($/1,000 gallons treated)
22 Advanced
Oxidation
Processes
Reference: 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
0.67 23
Ozonation
Reference: 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
bromate regulation, Cryptosporidium inactivation
requirements,1998
0.15 - 0.32
24 Ion Exchange
Reference: CH2M Hill study on San Gabriel Basin, for
135 mgd central treatment facility - ion exchange to
remove nitrate, 1990
0.73 - 0.97
EXHIBIT 1