Napa City Council
June 21, 2022

CITY OF NAPA
PUBLIC WATER SYSTEM 2810003

REPORT ON WATER QUALITY

RELATIVE TO PUBLIC HEALTH GOALS

JUNE 2022
ATTACHMENT 1

2 CITY OF NAPA PUBLIC WATER SYSTEM 2810003

REPORT ON WATER QUALITY RELATIVE TO PUBLIC HEALTH GOALS

TABLE OF CONTENTS

SECTION I: BACKGROUND INFORMATION 3

BACKGROUND 3

WHAT ARE PUBLIC HEALTH GOALS (PHGs)? 3

HOW ARE PHGS ESTABLISHED? 4

WATER QUALITY DATA CONSIDERED 5

GUIDELINES FOLLOWED 5

BEST AVAILABLE TREATMENT TECHNOLOGY AND COST ESTIMATES 6

SECTION II: CONSTITUENTS DETECTED THAT EXCEED PHGs OR MCLGs 6

BROMATE 6

COLIFORM BACTERIA 7

COPPER 8

TOTAL TRIHALOMETHANES 8

SECTION III: RECOMMENDATIONS FOR FURTHER ACTION 9

REFERENCES 9

EXERT FROM CALIFORNIA HEALTH AND SAFETY CODE: SECTION 116470 (B) 10

TABLE OF REGULATED CONSITUTENTS WITH MCLs, PHGs OR MCLGs 11

HEALTH RISK INFORMATION FOR PUBLIC HEALTH GOAL EXCEEDANCE REPORTS 22

CITY OF NAPA 2019 DRINKING WATER QUALITY REPORT 40

CITY OF NAPA 2020 DRINKING WATER QUALITY REPORT 46

CITY OF NAPA 2021 DRINKING WATER QUALITY REPORT 52

ATTACHMENT 1

3 SECTION I: BACKGROUND INFORMATION

BACKGROUND

Provisions of the California Health and Safety Code (Reference No. 1) specify that larger (>10,000 service connections) water utilities prepare a special report by July 1 of the year in which it is due if their water quality measurements have exceeded any Public Health Goals (PHGs). PHGs are non-enforceable goals established by the Cal- EPA’s Office of Environmental Health Hazard Assessment (OEHHA). The law also requires that where OEHHA has not adopted a PHG for a constituent, the water suppliers are to use the Maximum Contaminant Level Goals (MCLGs) adopted by United States Environmental Protection Agency (USEPA). Only constituents which have a California primary drinking water standard and for which either a PHG or MCLG has been set are to be addressed. (Reference No. 2 is a list of all regulated constituents with the Maximum Contaminant Level [MCLs] and PHGs or MCLGs.)

If a constituent was detected in the System’s water supply between 2019 and 2021 at a level exceeding an applicable PHG or MCLG, this report provides the information required by the law. Included is the numerical risk associated with the MCL and the PHG or MCLG, the category or type of risk to health that could be associated with each constituent, the best treatment technology available that could be used to reduce the constituent level, and an estimate of the cost to install that treatment if it is appropriate and feasible.

There are a few constituents that are routinely detected in water systems at levels usually well below the drinking water standards for which no PHG nor MCLG has yet been adopted by OEHHA or USEPA. These will be addressed in a future required report after a PHG has been adopted.

California Health and Safety code section 116470 (b) requires water agencies to prepare a report and hold a public meeting for the purpose of accepting and responding to public comments on the report. The City of Napa Utilities Department will present this report at a City Council meeting by December 2022.

WHAT ARE PUBLIC HEALTH GOALS (PHGs)?

PHGs are non-enforceable goals set by the OEHHA, which is part of Cal-EPA, and are based solely on public health risk considerations. PHGs are not required to be met by any public water system and none of the practical risk-management factors that are considered by the USEPA or the State Water Resource Control Board Division (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. However, state law requires DDW to set drinking water standards for chemical contaminants as close to the corresponding PHG as is economically and technologically feasible. In some cases, it may not be feasible for SWRCB to set the drinking water standard for a contaminant at the same level as the PHG as the technology to treat the chemicals may not be available or the cost of the treatment may be very high. MCLGs are the federal equivalent to PHGs.

ATTACHMENT 1

4 HOW ARE PHGs ESTABLISHED?

The PHG describes concentrations of contaminants at which adverse health effects would not be expected to occur, even over a lifetime of exposure. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water daily over a lifetime.

The California Safe Drinking Water Act of 1996 (amended Health and Safety Code, Section 116365) requires the OEHHA to adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires OEHHA to adopt PHGs that meet the following criteria:

1. PHGs for acutely toxic substances shall be set at levels at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of-safety.

2. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.

3. To the extent the information is available, OEHHA shall consider possible synergistic effects resulting from exposure to two or more contaminants.

4. OEHHA shall consider the existence of groups in the population that are more susceptible to adverse effects of the contaminants than a normal healthy adult.

5. OEHHA shall consider the contaminant exposure and body burden levels that alter physiological function or structure in a manner that may significantly increase the risk of illness.

6. In cases of scientific ambiguity, OEHHA shall use criteria most protective of public health and shall incorporate uncertainty factors of noncarcinogenic substances for which scientific research indicates a safe dose-response threshold.

7. In cases where scientific evidence demonstrates that a safe dose-response threshold for a contaminant exists, then the PHG should be set at that threshold.

8. The PHG may be set at zero if necessary, to satisfy the requirements listed above.

9. OEHHA shall consider exposure to contaminants in media other than drinking water, including food and air and the resulting body burden.

10. PHGs adopted by OEHHA shall be reviewed periodically and revised as necessary based on the availability of new scientific data.

PHGs adopted by OEHHA are for use by the SWRCB in establishing primary drinking water standards (State Maximum Contaminant Levels, or MCLs). MCLs are the ATTACHMENT 1

5 regulatory definition of what is “safe” and are the criteria for being in compliance.

Whereas PHGs are to be based solely on scientific and public health considerations without regard to economic cost considerations, drinking water standards adopted by SWRCB are to consider economic factors and technical feasibility.

For this reason, PHGs are only one part of the information used by DDW for establishing drinking water standards. PHGs established by OEHHA exert no regulatory burden and represent only non-mandatory goals. By federal law, MCLs established by DDW must be at least as stringent as the federal MCL if one exists. PHG documents are developed for technical assistance to SWRCB, but may also benefit federal, state and local public health officials. While the PHGs are calculated for single chemicals only, they may, if the information is available, address hazards associated with the interactions of contaminants in mixtures.

Further, PHGs are derived for drinking water only and are not to be utilized as target levels for the contamination of environmental waters where additional concerns of bioaccumulation in fish and shellfish may pertain. Often environmental water contaminant criteria are more stringent than drinking water PHGs, to account for human exposures to a single chemical in multiple environmental media and from bioconcentration by plants and animals in the food chain.

WATER QUALITY DATA CONSIDERED:

The origins of the three source waters for the City of Napa are: Lake Hennessey, Lake Milliken and the Sacramento Delta. The water quality data collected (throughout our water treatment plant processes, at key locations in the distribution system, and even at some customers’ taps) by our water system between 2019 and 2021 for purposes of determining compliance with drinking water standards and PHG reporting requirements was considered.

This data was all summarized in our Annual Drinking Water Quality Reports (Consumer Confidence Repots) that are available to customers on an annual basis by July 1st of each year following the monitoring year. If you required further information concerning contaminants and their potential health effects, please contact Erin Kebbas, Water Quality Manager, at (707) 253-0822.

GUIDELINES FOLLOWED:

The Association of California Water Agencies (ACWA) formed a workgroup, which prepared guidelines for water utilities to use in preparing these newly required reports. The most recent ACWA guidelines (ACWA, “2019 PHG Guidance”) were used in the preparation of our report. No guidance materials are available from DDW or OEHHA regarding preparation of this PHG report. Although OEHHA has a requirement to determine and provide information on “numerical health risk,” they otherwise have no involvement or authority regarding the report.

ATTACHMENT 1

6 BEST AVAILABLE TREATMENT TECHNOLOGY AND COST ESTIMATES:

Both the USEPA and SWRCB adopt what are known as BATs or Best Available Technologies, which are the best-known methods of reducing contaminant levels below the MCL. Cost 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 constituent downward to or near the PHG or MCLG, many of which are set at zero. Estimating the costs to reduce a constituent to zero is difficult if not impossible because it is not possible to verify by analytical means that the level has been lowered to zero. In some cases, installing treatment to try and further reduce very low levels of one constituent may have adverse effects on other aspects of water quality. In addition, the money that would be required for additional treatment processes might provide greater public health protection benefits if spent on other water system operation, surveillance and monitoring programs for the City of Napa.

SECTION II: CONSTITUENTS DETECTED THAT EXCEED PHGs OR MCLGs

The following is a discussion of the constituents that were detected in our drinking water at levels above the PHG or MCLG:

BROMATE:

The MCL for bromate is 0.010 mg/L. Bromate compliance is based on the highest running annual average (RAA) and not on a single sample result. The PHG for bromate is 0.0001 mg/L.

The category of health risk for bromate is carcinogenicity or capable of producing cancer.

Based on compliance sampling of our drinking water between 2019 and 2021, results varied from non-detect (“0”) to 0.003 mg/L. The tri-annual average result was 0.001 mg/L. Bromate is a byproduct formed when naturally occurring bromide reacts with ozone during the drinking water disinfection process.

Our water system is in full compliance with the State regulatory requirements for bromate. Therefore, it is not prudent to initiate additional treatment and there could be additional water quality issues raised. Therefore, no estimate of cost has been included.

CONSTITUENT PHG or (MCLG) MCL
City of Napa

TRI-ANNUAL

AVERAGE
Bromate 0.0001 mg/L 0.010 mg/L 0.001 mg/L

ATTACHMENT 1

7 COLIFORM BACTERIA:

The MCL for coliform is 5% positive samples of all samples per month and the MCLG is zero. The reason for the coliform drinking water standard is to minimize the possibility of the water containing pathogens, which are organisms that cause waterborne disease. Because coliform 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,” they indicated that they cannot do so with coliforms.

The City of Napa collected 25 samples for the analysis of total coliform bacteria each week from selected sites throughout the distribution system, as required by the SWRCB. Occasionally, samples were found to be positive for coliform bacteria but repeat samples were negative and follow up actions were taken. Of these samples, a maximum of 1.49% in 2019, 0.97% in 2020 and 1.53% in 2021 were positive in any month.

Coliform bacteria are indicator organisms that are found everywhere 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 follow up sampling done. It is not at all unusual for a system to have an occasional positive sample. It is difficult, if not impossible, to assure that a system will never have a positive sample.

We add chlorine at our treatment plants 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 disinfection byproduct level. This careful balance of treatment processes is essential to continue supplying our customers with safe drinking water.

Other equally important measures that we have implemented include: an effective cross-connection control program, disinfection residual maintenance throughout the majority of the system, an effective monitoring and surveillance program and maintaining positive pressures in our distribution system to minimize the chance of constituent intrusion. Our system has already taken all the steps described by SWRCB as BATs for coliform bacteria in Section 64447, Title 22, California Code of Regulations.

CONSTITUENT PHG or (MCLG) MCL
City of Napa

TRI-ANNUAL

AVERAGE
Total Coliform
Bacteria (Zero)
5% of samples
collected in month
positive

1.33%

ATTACHMENT 1

8 COPPER:

There is no MCL for copper. Instead, the 90th percentile value of all samples from household taps in the distribution system cannot exceed the Action Level (AL) of 1.3 mg/L for copper. The PHG for copper is 0.3 mg/L.

The category of health risk for copper is gastrointestinal irritation. Numerical health risk data on copper have not yet been provided by OEHHA, the State agency responsible for providing that information. (Reference No. 2)

After years of monitoring, the City of Napa has demonstrated copper does not exist in significant amounts within the distribution system and is granted triennial monitoring.

Based on triennial sampling of our distribution system for this PHG reporting period performed in 2021, our 90th percentile value for copper was 0.33 mg/L.

Our water system is in full compliance with the Federal and State Lead and Copper Rule. Based on our sampling results, it was determined according to State regulatory requirements that we meet the Action Levels for Copper. Therefore, we are deemed by SWRCB to have “optimized corrosion control” for our system.

Since we are meeting the “optimized corrosion control” requirements, it is not prudent to initiate additional corrosion control treatment as it involves the addition of other chemicals and there could be additional water quality issues raised. Therefore, no estimate of cost has been included.

CONSTITUENT PHG or (MCLG) AL
City of Napa

TRI-ANNUAL

AVERAGE
Copper 0.3 mg/L 1.3 mg/L 0.33 mg/L

TOTAL TRIHALOMETHANES:

The MCL for total trihalomethanes is 0.080 mg/L. Total trihalomethane compliance is based on a locational running annual average (LRAA) and not on a single sample result.

There are no MCLs for individual trihalomethanes. PHGs for individual trihalomethane species vary between 0.00006 and 0.0005 mg/L

The category of health risk for trihalomethanes are carcinogenicity or capable of producing cancer.

Based on compliance sampling of our drinking water between 2019 and 2021, individual location results varied from 0.02 mg/L to 0.09 mg/L. The tri-annual average result was 0.07 mg/L. Trihalomethanes are byproducts formed when naturally occurring organics reacts with chlorine during the drinking water disinfection process.

Our water system is in full compliance with the State regulatory requirements for the 2022 PHG Report. We have continuous water system improvements, specifically designed for trihalomethanes. Therefore, no estimate of cost has been included.

ATTACHMENT 1

9 CONSTITUENT PHG or (MCLG) MCL
City of Napa

TRI-ANNUAL

AVERAGE
Total
Trihalomethanes 0.00006 – 0.0005 0.08 ug/L 0.07 mg/L

SECTION III: RECOMMENDATIONS FOR FURTHER ACTION:

The drinking water quality of the City of Napa meets all SWRCB and USEPA drinking water standards set to protect public health.

To further reduce the levels of the constituents identified in this report that are already significantly below the health based MCLs established to provide “safe drinking water,” additional costly treatment processes would be required. The costs associated with incorporating additional treatment processes may be better utilized to provide greater public health protection benefits if spent in other aspects such as maintenance, operation and water quality monitoring programs.

The effectiveness of the treatment processes to provide any significant reductions in constituent levels at these already low values is uncertain. The health protection benefits of these further hypothetical reductions are not clear and may not be quantifiable. Therefore, no action is proposed at this time.

REFERENCES:

No. 1 Excerpt from California Health & Safety Code: Section 116470 (b) No. 2 Table of Regulated Constituents with MCLs, PHGs or MCLGs No. 3 Health Risk Information for Public Health Goal Exceedance Reports. Prepared by the Office of Environmental Health Hazard Assessment. February 2022 No. 4 City of Napa’s 2019, 2020 and 2021 Water Quality Reports ATTACHMENT 1

California Health and Safety Code, Section 116470 (b)

(b) On or before July 1, 1998, and every three years thereafter, public water systems serving more than 10,000 service connections that detect one or more contaminants in drinking water that exceed the applicable public health goal, shall prepare a brief written report in plain language that does all of the following:

(1) identifies each contaminant detected in drinking water that exceeds the applicable public health goal
(2) Discloses the numerical public health risk, determined by the office, associated with the maximum contaminant level for each contaminant level for each contaminant identified paragraph (1) and the numerical public health risk determined by the office associated with the public health goal for that contaminant.
(3) Identifies the category of risk to public health, including, but not limited to, carcinogenic, mutagenic, teratogenic, and acute toxicity, associated with exposure to the contaminant in drinking water, and includes a brief plainly worded description of these terms.
(4) Describes the best available technology, if any is then available on a commercial basis, to remove the contaminant or reduce the concentration of the contaminant. The public water system may, solely at its own discretion, briefly describe actions that have been taken on tis own, or by other entities, to prevent the introduction of the contaminant into drinking water supplies. (5) Estimates the aggregate cost and the cost per customer of utilizing the technology described in paragraph (4), if any, to reduce the concentration of that contaminant in drinking water to a level at or below the public health goal. (6) Briefly describes what action, if any, the local water purveyor intends to take to reduce the concentration of the contaminant in public drinking water supplies and the basis for that decision.

(c) Public water systems required to prepare a report pursuant to subdivision (b) shall hold a public hearing for the purpose of accepting and responding to public comment on the report. Public water systems may hold the public hearing as part of any regularly scheduled meeting.

(d) The department shall not require a public water system to take any action to reduce or eliminate any exceedance of a public health goal.

(e) Enforcement of this section does not require the department to amend a public water systems operating permit.

(f) Pending adoption of a public health goal by the Office of Environmental Health Hazard Assessment pursuant to subdivision (c) of Section 116365, and in lieu thereof, public water systems shall use the national maximum contaminant level goal adopted by the United States Environmental Protection Agency for the corresponding contaminant for purposes of complying with the notice and hearing requirements of this section.

(g) This section is intended to provide an alternative form for the federally required consumer confidence report as authorized by 42 U.S.C. section 300g-3(c).

ATTACHMENT 1

MCLs, DLRs, PHGs, for Regulated Drinking Water Contaminants (Units are in milligrams per liter (mg/L), unless otherwise noted.) Last Update: September 14, 2021
The following tables includes California’s maximum contaminant levels (MCLs), detection limits for purposes of reporting (DLRs), public health goals (PHGs) from the Office of Environmental Health Hazard Assessment (OEHHA). For comparison, Federal MCLs and Maximum Contaminant Level Goals (MCLGs) (USEPA) are also displayed.

Inorganic Chemicals Table, Chemicals with MCLs in 22 CCR §64431 State Regulated
Inorganic Chemical
Contaminant
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
Aluminum 1 0.05 0.6 2001 -- --
Antimony 0.006 0.006 0.001 2016 0.006 0.006
Arsenic 0.010 0.002 0.000004 2004 0.010 zero
Asbestos (MFL =
million fibers per liter;
for fibers >10
microns long)
7 MFL 0.2 MFL 7 MFL 2003 7 MFL 7 MFL
Barium 1 0.1 2 2003 2 2
Beryllium 0.004 0.001 0.001 2003 0.004 0.004
Cadmium 0.005 0.001 0.00004 2006 0.005 0.005
Chromium, Total -
OEHHA withdrew the

0.0025-mg/L PHG

0.05 0.01 withdrawn
Nov. 2001
1999 0.1 0.1
ATTACHMENT 1

State Regulated
Inorganic Chemical
Contaminant
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
Chromium,
Hexavalent - 0.01-
mg/L MCL & 0.001-
mg/L DLR repealed
September 2017
-- -- 0.00002 2011 -- --
Cyanide 0.15 0.1 0.15 1997 0.2 0.2
Fluoride 2 0.1 1 1997 4.0 4.0
Mercury (inorganic) 0.002 0.001 0.0012 1999
(rev2005)*

0.002 0.002
Nickel 0.1 0.01 0.012 2001 -- --
Nitrate (as nitrogen,
N)
10 as N 0.4 45 as NO3
(=10 as N)
2018 10 10
Nitrite (as N) 1 as N 0.4 1 as N 2018 1 1
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 0.05 0.05
Thallium 0.002 0.001 0.0001 1999
(rev2004)

0.002 0.0005
ATTACHMENT 1

Copper and Lead Table, 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.

State Regulated
Copper and Lead
Contaminant
State
MCL
State
DLR
State
PHG
State
Date of
PHG
Federal
MCL
Federal
MCLG
Copper 1.3 0.05 0.3 2008 1.3 1.3
Lead 0.015 0.005 0.0002 2009 0.015 zero
Radiological Table, Radionuclides with MCLs in 22 CCR §64441 and §64443 [units are picocuries per liter (pCi/L), unless otherwise state; n/a = not applicable] State Regulated
Radionuclides
Contaminant
State
MCL
State
DLR
State
PHG
State
Date of
PHG
Federal
MCL
Federal
MCLG
Gross alpha particle
activity - OEHHA
concluded in 2003 that
a PHG was not
practical
15 3 none n/a 15 zero
Gross beta particle
activity - OEHHA
concluded in 2003 that
a PHG was not
practical
4 mrem/yr
4 none n/a 4
mrem/yr
zero
Radium-226 -- 1 0.05 2006
Radium-228 -- 1 0.019 2006
Radium-226 + Radium- 5 -- -- -- 5 zero
ATTACHMENT 1

State Regulated
Radionuclides
Contaminant
State
MCL
State
DLR
State
PHG
State
Date of
PHG
Federal
MCL
Federal
MCLG
228
Strontium-90 8 2 0.35 2006 -- --
Tritium "20,000" "1,000" 400 2006 -- --
Uranium 20 1 0.43 2001 30 µg/L zero
Organic Chemicals Table, Chemicals with MCLs in 22 CCR §64444 Volatile Organic Chemicals (VOCs)
State Regulated
Volatile Organic
Contaminants
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
Benzene 0.001 0.0005 0.00015 2001 0.005 zero
Carbon tetrachloride 0.0005 0.0005 0.0001 2000 0.005 zero 1,2-Dichlorobenzene 0.6 0.0005 0.6 1997
(rev2009)

0.6 0.6
1,4-Dichlorobenzene (p-
DCB)

0.005 0.0005 0.006 1997 0.075 0.075
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)

0.005 zero
ATTACHMENT 1

State Regulated
Volatile Organic
Contaminants
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
1,1-Dichloroethylene
(1,1-DCE)

0.006 0.0005 0.01 1999 0.007 0.007
cis-1,2-Dichloroethylene 0.006 0.0005 0.013 2018 0.07 0.07 trans-1,2-
Dichloroethylene

0.01 0.0005 0.05 2018 0.1 0.1
Dichloromethane
(Methylene chloride)

0.005 0.0005 0.004 2000 0.005 zero
1,2-Dichloropropane 0.005 0.0005 0.0005 1999 0.005 zero 1,3-Dichloropropene 0.0005 0.0005 0.0002 1999
(rev2006)
-- --
Ethylbenzene 0.3 0.0005 0.3 1997 0.7 0.7
Methyl tertiary butyl
ether (MTBE)

0.013 0.003 0.013 1999 -- --
Monochlorobenzene 0.07 0.0005 0.07 2014 0.1 0.1
Styrene 0.1 0.0005 0.0005 2010 0.1 0.1
1,1,2,2-
Tetrachloroethane

0.001 0.0005 0.0001 2003 0.1 0.1
Tetrachloroethylene
(PCE)

0.005 0.0005 0.00006 2001 0.005 zero
ATTACHMENT 1

State Regulated
Volatile Organic
Contaminants
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
Toluene 0.15 0.0005 0.15 1999 1 1
1,2,4-Trichlorobenzene 0.005 0.0005 0.005 1999 0.07 0.07 1,1,1-Trichloroethane
(1,1,1-TCA)

0.200 0.0005 1 2006 0.2 0.2
1,1,2-Trichloroethane
(1,1,2-TCA)

0.005 0.0005 0.0003 2006 0.005 0.003
Trichloroethylene (TCE) 0.005 0.0005 0.0017 2009 0.005 zero 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 0.002 zero
Xylenes 1.750 0.0005 1.8 1997 10 10
Non-Volatile Synthetic Organic Chemicals (SOCs)
State Regulated
Non-Volatile
Synthetic Organic
Contaminants
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
Alachlor 0.002 0.001 0.004 1997 0.002 zero
ATTACHMENT 1

State Regulated
Non-Volatile
Synthetic Organic
Contaminants
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
Atrazine 0.001 0.0005 0.00015 1999 0.003 0.003
Bentazon 0.018 0.002 0.2 1999
(rev2009)
-- --
Benzo(a)pyrene 0.0002 0.0001 0.000007 2010 0.0002 zero
Carbofuran 0.018 0.005 0.0007 2016 0.04 0.04
Chlordane 0.0001 0.0001 0.00003 1997
(rev2006)

0.002 zero
Dalapon 0.2 0.01 0.79 1997
(rev2009)

0.2 0.2
1,2-Dibromo-3-
chloropropane
(DBCP)

0.0002 0.00001 0.000003 2020 0.0002 zero
2,4-
Dichlorophenoxyaceti
c acid (2,4-D)

0.07 0.01 0.02 2009 0.07 0.07
Di(2-
ethylhexyl)adipate

0.4 0.005 0.2 2003 0.4 0.4
Di(2-
ethylhexyl)phthalate
(DEHP)

0.004 0.003 0.012 1997 0.006 zero
Dinoseb 0.007 0.002 0.014 1997 0.007 0.007
ATTACHMENT 1

State Regulated
Non-Volatile
Synthetic Organic
Contaminants
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
(rev2010)
Diquat 0.02 0.004 0.006 2016 0.02 0.02
Endothal 0.1 0.045 0.094 2014 0.1 0.1
Endrin 0.002 0.0001 0.0003 2016 0.002 0.002
Ethylene dibromide
(EDB)

0.00005 0.00002 0.00001 2003 0.0000
5 zero
Glyphosate 0.7 0.025 0.9 2007 0.7 0.7
Heptachlor 0.00001 0.00001 0.000008 1999 0.0004 zero
Heptachlor epoxide 0.00001 0.00001 0.000006 1999 0.0002 zero Hexachlorobenzene 0.001 0.0005 0.00003 2003 0.001 zero
Hexachlorocyclopent
adiene

0.05 0.001 0.002 2014 0.05 0.05
Lindane 0.0002 0.0002 0.000032 1999
(rev2005)

0.0002 0.0002
Methoxychlor 0.03 0.01 0.00009 2010 0.04 0.04
Molinate 0.02 0.002 0.001 2008 -- --
Oxamyl 0.05 0.02 0.026 2009 0.2 0.2
ATTACHMENT 1

State Regulated
Non-Volatile
Synthetic Organic
Contaminants
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
Pentachlorophenol 0.001 0.0002 0.0003 2009 0.001 zero
Picloram 0.5 0.001 0.166 2016 0.5 0.5
Polychlorinated
biphenyls (PCBs)

0.0005 0.0005 0.00009 2007 0.0005 zero
Simazine 0.004 0.001 0.004 2001 0.004 0.004
Thiobencarb 0.07 0.001 0.042 2016 -- --
Toxaphene 0.003 0.001 0.00003 2003 0.003 zero
1,2,3-
Trichloropropane

0.00000
5 0.00000
5 0.0000007 2009 -- --
2,3,7,8-TCDD
(dioxin)
3x10-8 5x10-9 5x10-11 2010 3x10-8 zero
2,4,5-TP (Silvex) 0.05 0.001 0.003 2014 0.05 0.05
Disinfection Byproducts Table, Chemicals with MCLs in 22 CCR §64533 State Regulated
Disinfection
Byproducts
Contaminants
State
MCL
State
DLR
State
PHG
State
Date of
PHG
Federal
MCL
Federal
MCLG
Total Trihalomethanes 0.080 -- -- -- 0.080 --
ATTACHMENT 1

State Regulated
Disinfection
Byproducts
Contaminants
State
MCL
State
DLR
State
PHG
State
Date of
PHG
Federal
MCL
Federal
MCLG
Bromodichloromethane -- 0.0010 0.00006 2020 -- zero
Bromoform -- 0.0010 0.0005 2020 -- zero
Chloroform -- 0.0010 0.0004 2020 -- 0.07
Dibromochloromethane -- 0.0010 0.0001 2020 -- 0.06
Haloacetic Acids (five)
(HAA5)

0.060 -- -- -- 0.060 --
Monochloroacetic Acid -- 0.0020 -- -- -- 0.07
Dichloroacetic Adic -- 0.0010 -- -- -- zero
Trichloroacetic Acid -- 0.0010 -- -- -- 0.02
Monobromoacetic Acid -- 0.0010 -- -- -- --
Dibromoacetic Acid -- 0.0010 -- -- -- --
Bromate 0.010 0.0050** 0.0001 2009 0.01 zero
Chlorite 1.0 0.020 0.05 2009 1 0.8
ATTACHMENT 1

Chemicals with PHGs established in response to DDW requests. These are not currently regulated drinking water contaminants.

State Regulated
Disinfection
Byproducts
Contaminants
State
MCL
State
DLR
State PHG State
Date of
PHG
Federal
MCL
Federal
MCLG
N-Nitrosodimethylamine
(NDMA)
-- -- 0.000003 2006 -- --
*OEHHA's review of this chemical during the year indicated (rev20XX) resulted in no change in the PHG.
**The DLR for Bromate is 0.0010 mg/L for analysis performed using EPA Method 317.0 Revision 2.0, 321.8, or 326.0.

ATTACHMENT 1

DRAFT – FOR REVIEW ONLY

OFFICE OF ENVIRONMENTAL HEALTH HAZARD ASSESSMENT
Public Health Goals

Health Risk Information
for Public Health Goal
Exceedance Reports

February 2022
Pesticide and Environmental Toxicology Branch
Office of Environmental Health Hazard Assessment
California Environmental Protection Agency
ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 1
Health Risk Information for
Public Health Goal Exceedance Reports
Prepar
ed by
Office of Environmental Health Hazard Assessment
Cali
fornia Environmental Protection Agency
February 2022
NEW for the 2022 Report: New in this document are an updated Public Health Goal (PHG) fo
r 1,2-dibromo-3-chloropropane (DBCP) and newly established PHGs for the tri
halomethanes bromodichloromethane, bromoform, chloroform, and dibr
omochloromethane.

Background: Under the Calderon-Sher Safe Drinking Water Act of 1996 (the Act), publ
ic
water systems with more than 10,000 service connections are required to prepare a r
eport every three years for cont aminants that exce ed their respective PHGs.1 This
document contains health risk information on regulated drinking water contam
inants to assist public water systems in preparing these reports. A PHG is the concen
tration of a contaminant in drinking water that poses no significant health risk if consumed for a lifetime. PHGs are developed and published by the Of fice of Environmental Health Hazard Assessment (OEHHA) using current risk assessment princip
les, practices and methods.2
The water
system’s report is required to identify the healt h risk category (e.g., car
cinogenicity or neurotoxicity) associ ated with exposure to each regulated contaminant in drinking water and to include a brief, plainly worded description of these r
isks. 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 co
ntaminant. This health risk information document is prepared by OEHHA every three yea
rs to assist the water systems in providing the required information in their repo
rts.
1 Health and Safety Code Section 116470(b)
2 Health and Safety Code Section 116365
ATTACHMENT 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 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 (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).

ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 3
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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)
1×10-6
(one per
million)

0.01 2.5×10-3
(2.5 per
thousand)
Asbestos carcinogenicity
(causes cancer)
7 MFL7
(fibers >10
microns in
length)
1×10-6 7 MFL
(fibers >10
microns in
length)
1×10-6
(one per
million)
Atrazine carcinogenicity
(causes cancer)

0.00015 1×10-6 0.001 7×10-6
(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. 1×10-6 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.

ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 4
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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 1×10-6 0.001 7×10-6
(seven per
million)
Benzo[a]pyrene carcinogenicity
(causes cancer)

0.000007
(7×10-6)
1×10-6 0.0002 3×10-5
(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 1×10-6 0.01 1×10-4
(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.

ATTACHMENT 1

Offi
ce of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 5
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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 1×10-6 0.0005 5×10-6
(five per
million)
Chlordane carcinogenicity
(causes cancer)

0.00003 1×10-6 0.0001 3×10-6
(three per
million)
Chlorite hematotoxicity
(causes anemia)
neurotoxicity
(causes neurobehavioral
effects)

0.05 NA 1 NA
Chromium,
hexavalent
carcinogenicity
(causes cancer)

0.00002 1×10-6 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).

ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 6
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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 1×10-6 0.004 3×10-7
(three per
ten million)
1,2-Dibromo-3-
chloropropane
(DBCP)
carcinogenicity
(causes cancer)

0.000003
(3x10-6)
1×10-6 0.0002 7×10-5
(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 1×10-6 0.005 8×10-7
(eight per
ten million)
1,1-Dichloro-
ethane
(1,1-DCA)
carcinogenicity
(causes cancer)

0.003 1×10-6 0.005 2×10-6
(two per
million)
1,2-Dichloro-
ethane
(1,2-DCA)
carcinogenicity
(causes cancer)

0.0004 1×10-6 0.0005 1×10-6
(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
ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 7
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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 1×10-6 0.005 1×10-6
(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 1×10-6 0.005 1×10-5
(one per
hundred
thousand)
1,3-Dichloro-
propene
(Telone II)
carcinogenicity
(causes cancer)

0.0002 1×10-6 0.0005 2×10-6
(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
ATTACHMENT 1

Offi
ce of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 8
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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 1×10-6 0.00005 5×10-6
(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)
1×10-6 0.00001 1×10-6
(one per
million)
Heptachlor
epoxide
carcinogenicity
(causes cancer)

0.000006
(6×10-6)
1×10-6 0.00001 2×10-6
(two per
million)
Hexachloroben-
zene
carcinogenicity
(causes cancer)

0.00003 1×10-6 0.001 3×10-5
(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 <1×10-6
(PHG is
not based
on this
effect)

0.015
(AL9)
2×10-6
(two per
million)
ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 9
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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
(γ-BHC)
carcinogenicity
(causes cancer)

0.000032 1×10-6 0.0002 6×10-6
(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 1×10-6 0.013 1×10-6
(one per
million)
Molinate carcinogenicity
(causes cancer)

0.001 1×10-6 0.02 2×10-5
(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
ATTACHMENT 1

Offi
ce of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 10
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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
(3×10-6)
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 1×10-6 0.001 3×10-6
(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 1×10-6 0.0005 6×10-6
(six per
million)
Radium-226 carcinogenicity
(causes cancer)

0.05 pCi/L 1×10-6 5 pCi/L
(combined
Ra226+228)
1×10-4
(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.

ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 11
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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 1×10-6 5 pCi/L
(combined
Ra226+228)
3×10-4
(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 2×10-5
(two per
hundred
thousand)
Styrene
(vinylbenzene)
carcinogenicity
(causes cancer)

0.0005 1×10-6 0.1 2×10-4
(two per
ten
thousand)
1,1,2,2-
Tetrachloro-
ethane
carcinogenicity
(causes cancer)

0.0001 1×10-6 0.001 1×10-5
(one per
hundred
thousand)
2,3,7,8-Tetra-
chlorodibenzo-p-
dioxin (TCDD, or
dioxin)
carcinogenicity
(causes cancer)

5×10-11 1×10-6 3×10-8 6×10-4
(six per ten
thousand)
ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 12
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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 1×10-6 0.005 8×10-5
(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 1×10-6 0.003 1×10-4
(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
ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 13
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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 2×10-5
(two per
hundred
thousand)
Trichloro-
ethylene (TCE)
carcinogenicity
(causes cancer)

0.0017 1×10-6 0.005 3×10-6
(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)
7×10-6
(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* 1.3×10-3
(1.3 per
thousand)11
Trihalomethanes:

Bromoform
carcinogenicity
(causes cancer)

0.0005 1x10-6 0.080* 2×10-4
(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.

ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 14
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs)
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* 2×10-4
(two per ten
thousand)13
Trihalomethanes:

Dibromochloro-
methane
carcinogenicity
(causes cancer)

0.0001 1x10-6 0.080* 8×10-4
(eight
per ten
thousand)14
Tritium carcinogenicity
(causes cancer)
400 pCi/L 1x10-6 20,000
pCi/L
5×10-5
(five per
hundred
thousand)
Uranium carcinogenicity
(causes cancer)

0.43 pCi/L 1×10-6 20 pCi/L 5×10-5
(five per
hundred
thousand)
Vinyl chloride carcinogenicity
(causes cancer)

0.00005 1×10-6 0.0005 1×10-5
(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.

ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 15
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
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 changes
8)

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. 1×10-6 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.

ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 16
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
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.

ATTACHMENT 1

Office of Environmental Health Hazard Assessment
Water Toxicology Section
February 2022 17
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
emitters
9 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)

ATTACHMENT 1

WATER
REPORT
Quality
annual
REPORTING YEAR 2019
Presented By
PWS ID#: 2810003
Este informe contiene información muy importante sobre su agua potable. T radúzcalo o hable con alguien que lo entienda bien.

ATTACHMENT 1

Questions?
For more information about this report, or for any questions relating to your drinking water, please call Erin Kebbas, Water Quality Manager, at (707) 253-0822. For questions concerning the City of Napa Water Division in general, please call (707) 257-9521. See our website for up-to-date information on programs: www.cityofnapa.org/water. For emergencies or customer use during weekends and holidays, please call (707) 253-4451.

Our Mission Continues
W
e are once again pleased to present our annual water
quality report covering all testing performed between
January 1 and December 31, 2019. We
dedicate ourselves to producing drinking
water that meets all state and federal
standards. We continually strive to
adopt new methods for delivering the
best-quality drinking water to you. As
new challenges to drinking water safety
emerge, we remain vigilant in meeting
the goals of source water protection, water
conservation, and community education
while continuing to serve the needs of all our
water users.

Please remember that we are always available should you ever have any questions or concerns about your water.

Lead in Home Plumbing
I
f present, elevated levels of lead can cause serious health problems, especially for pregnant women and young
children. Lead in drinking water is primarily from materials and components associated with service lines and home
plumbing. Unlike other regions of the U.S. where lead was prevalent, it was not the predominant construction material used in the City of Napa for water service installations. In addition, years of monitoring show that the existing public system pipe network does not contribute lead to our drinking water. Our next lead and copper collection is scheduled for July 2021. The City of Napa is responsible for providing high- quality drinking water, but we cannot control the variety of materials used in plumbing components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 minutes before using water for drinking or cooking. (If you do so, you may wish to collect the flushed water and reuse it for another beneficial purpose, such as watering plants.) If you are concerned about lead in your water, you may wish to have your water tested. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline at (800) 426-4791 or at www.epa.gov/safewater/lead.

Community Participation
T
he City of Napa encourages citizens to participate in our City Council meetings, which take place on the first and third T uesday of each month from 3:30 to 5:00 p.m. and again from 6:30 to 9:00 p.m. in Council Chambers at City Hall, 955 School Street. For more information concerning city activities and Covid- 19 requirements, please see our website at www.cityofnapa.org.

Important Health Information
S
ome people may be more vulnerable to contaminants
in drinking water than the general population.

Immunocompromised persons such as persons
with cancer undergoing chemotherapy,
persons who have undergone organ
transplants, people with HIV/AIDS
or other immune system disorders,
some elderly, and infants may be
particularly at risk from infections.

These people should seek advice
about drinking water from their
health care providers. The U.S.

EPA/CDC (Centers for Disease
Control and Prevention)
guidelines on appropriate means
to lessen the risk of infection
by cryptosporidium and other
microbial contaminants are
available from the Safe Drinking
Water Hotline at (800) 426-4791 or http://water.epa.gov/ drink/hotline.

Protecting Your Water
B
acteria are a natural and important part of our world.

There are around 40 trillion bacteria living in each of us; without them, we would not be able to live healthy lives.

Coliform bacteria are common in the environment and are generally not harmful themselves. H owever, the presence of this bacterial form in drinking water is a concern because it indicates the water may be contaminated with other organisms that can cause disease.

In 2016 the U.S. EPA passed a regulation called the Revised T otal Coliform Rule, which requires additional steps that water systems must take in order to ensure the integrity of the drinking water distribution system by monitoring for the presence of bacteria like total coliform and E. coli. The rule requires more stringent standards than the previous regulation, and it requires water systems that may be vulnerable to contamination to have in place procedures that will minimize the incidence of contamination. Water systems that exceed a specified frequency of total coliform occurrences are required to conduct an assessment of their system and correct any problems quickly. The U.S. EPA anticipates greater public health protection under this regulation due to its more preventive approach to identifying and fixing problems that may affect public health.

Though we have been fortunate to have the highest-quality drinking water, our goal is to eliminate all potential pathways of contamination into our distribution system, and this requirement helps us to accomplish that goal.

ATTACHMENT 1

Protecting Our Watersheds
T
he City of Napa is devoted to protecting the land surrounding our local source waters in order to maintain the quality and purity of water used for Napa’s drinking water consumers. In the long term, protecting our watersheds is one of the least costly and most important actions we can take to reduce the risk of unwanted constituents in our drinking water. Algal growth due to the addition of nutrients is the number one cause of taste and odor affecting your tap water. Nutrients in the watershed are increased artificially by wastewater systems as well as fertilizers and runoff from agricultural practices.

Every five years, the City of Napa conducts a source water assessment to evaluate the quality of the water used as drinking water supply and examine activities associated with the specific waterway and surrounding areas to determine their contribution to contamination.

These potential contributors are then compiled into a Vulnerability Summary. Results from the Vulnerability Summaries show the most significant potential sources of contaminants for the City of Napa’s source waters are:

Lake Hennessey (completed April 2018): Pacific Union College Wastewater T reatment Plant, vineyards, fires, invasive species, potential hazardous material spills due to traffic accidents (on Highway 128 near lake), septic tank systems (in Angwin), grazing, and wild animals.

Lake Milliken (completed April 2018): Fires, vineyards, grazing, and wild animals.

Sacramento Delta (updated 2017): Recreational use, urban and agricultural runoff, grazing animals, herbicide application, and seawater intrusion.

Copies of the complete assessments are available through the SWRCB DDW , Santa Rosa District Office, 50 D Street, Suite 200, Santa Rosa, CA 95404 or by calling Amy Little, Associate Sanitary Engineer, SWRCB, at (707) 576-2145.

Count on Us
D
elivering high-quality drinking water to our customers
involves far more than just pushing water through
pipes. Water treatment is a complex, time-consuming process.

Because tap water is highly regulated by State and Federal laws, water treatment plant and system operators must be licensed and are required to commit to long-term, on-the-job training before becoming fully qualified. O ur licensed water professionals’ technical knowledge includes a wide range of subjects, including mathematics, biology, chemistry, and physics. Some of the tasks they complete on a regular basis include:
• Operating and maintaining equipment to purify and
clarify water;
• Monitoring and inspecting machinery, meters, gauges,
and operating conditions;
• Conducting tests and inspections on water and evaluating the results;
• Maintaining optimal water chemistry;
• Applying data to formulas that determine treatment
requirements, flow levels, and concentration levels;
• Documenting and reporting test results and system
operations to regulatory agencies; and
• Serving our community through customer support,
education, and outreach.

So the next time you turn on your faucet, think of the skilled professionals who stand behind each drop.

Ensuring Reliability of Your Water
During the COVID-19 Pandemic
O
ur existing d isinfection process that protects your
drinking water is effective against the novel coronavirus.

During this pandemic we have taken many precautionary steps to ensure we are able to keep clean, safe water flowing to you.

Highlights of precautions we enacted in early March 2020 and continue through the ongoing pandemic include:
• Securing redundancy in key supply chains such as
chemicals for water treatment process, repair parts and inventory for our pipe network
• T ransitioning engineering and admin staff to work
remotely
• Limiting physical interaction with water treatment
operators, by restricting entrance to the control room
• Modifying operations to keep water treatment plant
operators isolated at the Hennessey T reatment Plant
through the end of April after routine maintenance on our State Water Project facilities was completed
• Staggering shift hours to minimize overlap of staff in shared facilities
• Performing essential maintenance as usual wearing masks, social distancing, wearing PPE, increasing handwashing
and use of hand sanitizer
• Increasing cleaning and disinfecting all surfaces in control room and all touch points in facilities and vehicles
• Avoiding planned service interruptions to customers while construction was restricted under County Order
ATTACHMENT 1

Substances That Could Be in Water
T
he sources of drinking water (both tap water and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs, and wells.

As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from human activity.

In order to ensure that tap water is safe to drink, the U.S. Environmental Protection Agency (U.S. EPA) and the State Water Resources Control Board (SWRCB or State Board) prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. The U.S. Food and Drug Administration regulations and California law also establish limits for contaminants in bottled water that provide the same protection for public health. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that water poses a health risk.

Contaminants that may be present in source water include:

Microbial Contaminants, such as viruses and bacteria, that may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife;
Inorganic Contaminants, such as salts and metals, that can be naturally occurring or can result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming; Pesticides and Herbicides that may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses; Organic Chemical Contaminants, including synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum production, and which can also come from gas stations, urban stormwater runoff, agricultural applications, and septic systems;
Radioactive Contaminants that can be naturally occurring or can be the result of oil and gas production and mining activities.

More information about contaminants and potential health effects can be obtained by calling the U.S. EPA’s Safe Drinking Water Hotline at (800) 426-4791.

Where Does My Water Come From?
T
he City of Napa’s customers are fortunate because we enjoy an abundant water supply from three sources. Depending
on which water treatment plant is in operation, the source is Barker Slough in the Sacramento Delta via the North Bay Aqueduct (treated by the Edward I. Barwick Jamieson Canyon Water T reatment Plant), Lake Hennessey (treated by the Hennessey Water T reatment Plant), or Lake Milliken (treated by the Milliken Water T reatment Plant).

ATTACHMENT 1

T est Results
O
ur water is monitored for hundreds of different kinds of substances (including but not limited to metals or inorganic chemicals, volatile organic chemicals, man-made substances and disinfection by-products) on a very strict schedule and our goal is to keep any detections below their respective maximum allowed levels. Remember that detecting a substance does not mean the water is unsafe to drink. Here, in this report, we show only those substances that were detected in our water in 2019. Your water met all U.S. EPA and SWRCB standards in 2019.

We participated in the 4th stage of the U.S. EPA’s Unregulated Contaminant Monitoring Rule (UCMR4) program by performing additional tests on our drinking water. UCMR4 sampling benefits the environment and public health by providing the EPA with data on the occurrence of contaminants suspected to be in drinking water, in order to determine if the EPA needs to introduce new regulatory standards to improve drinking water quality. Unregulated contaminant monitoring data are available to the public, so please feel free to contact us if you are interested in obtaining that information. If you would like more information on the U.S. EPA’s Unregulated Contaminant Monitoring Rule, please call the Safe Drinking Water Hotline at (800) 426-4791.

REGULATED SUBSTANCES

SUBSTANCE
(UNIT OF MEASURE)
MCL
[MRDL]
PHG
(MCLG)
[MRDLG]
AMOUNT

DETECTED
(LRAA) [RAA]
RANGE

LOW-HIGH
IN

COMPLIANCE TYPICAL SOURCE
Bromate (ppb) 10 0.1 [ND] ND–2.8 Yes By-product of drinking water disinfection Chlorine (ppm) [4.0 (as Cl2)] [4.0 (as Cl2)] [0.80] 0.02–1.77 Yes Drinking water disinfectant added for treatment Control of DBP precursors [TOC]
(removal ratio)
TT NA 2.04 1.55–3.46 Yes Various natural and man-made sources Haloacetic Acids (ppb) 60 NA (35.1) ND–39.6 Yes By-product of drinking water disinfection T otal Coliform Bacteria [federal Revised
T otal Coliform Rule] (Positive samples)
TT NA 3 NA Yes Naturally present in the environment
TTHMs [T otal Trihalomethanes] (ppb) 80 NA (71.1) 29.5–72.9 Yes By-product of drinking water disinfection Definitions
90th %ile: The levels reported for lead and
copper represent the 90th percentile of the total
number of sites tested. The 90th percentile is equal
to or greater than 90% of our lead and copper
detections.

AL (Regulatory Action Level): The concentration
of a contaminant that, if exceeded, triggers
treatment or other requirements that a water
system must follow.
µS/cm (microsiemens per centimeter): A unit
expressing the amount of electrical conductivity of
a solution.

DBP: Disinfection By Product
LRAA (Locational Running Annual Average):

The average of sample analytical results for samples
taken at a particular monitoring location during
theprevious four calendar quarters. Amount
Detected values for TTHMs and HAAs are
reported as the highest LRAAs.

MCL (Maximum Contaminant Level): The
highest level of a contaminant that is allowed in
drinking water. Primary MCLs are set as close
to the PHGs (or MCLGs) as is economically
and technologically feasible. Secondary MCLs
(SMCLs) are set to protect the odor, taste, and
appearance of drinking water.

MCLG (Maximum Contaminant Level Goal):

The level of a contaminant in drinking water
below which there is no known or expected risk to
health. MCLGs are set by the U.S. EPA.

MRDL (Maximum Residual Disinfectant Level):

The highest level of a disinfectant allowed in
drinking water. There is convincing evidence that
addition of a disinfectant is necessary for control of
microbial contaminants.

MRDLG (Maximum Residual Disinfectant Level
Goal): The level of a drinking water disinfectant
below which there is no known or expected risk
to health. MRDLGs do not reflect the benefits
of the use of disinfectants to control microbial
contaminants.

NA: Not applicable
NS: No standard
NTU (Nephelometric T urbidity Units):

Measurement of the clarity, or turbidity, of water.

T urbidity in excess of 5 NTU is just noticeable to
the average person.

PDWS (Primary Drinking Water Standard):

MCLs and MRDLs for contaminants that affect
health along with their monitoring and reporting
requirements, and water treatment requirements.

PHG (Public Health Goal): The level of a
contaminant in drinking water below which there
is no known or expected risk to health. PHGs are
set by the California EPA.
ppb (parts per billion): One part substance per
billion parts water (or micrograms per liter).
ppm (parts per million): One part substance per
million parts water (or milligrams per liter).
removal ratio: A ratio between the percentage of a
substance actually removed to the percentage of the
substance required to be removed.

TOC: T otal Organic Carbon
TT (Treatment T echnique): A required process
intended to reduce the level of a contaminant in
drinking water.

ATTACHMENT 1

Filter Performance (Turbidity—the Standard Measure of Clarity in Water)

SUBSTANCE
(UNIT OF MEASURE) MCL PHG
AMOUNT

DETECTED
IN

COMPLIANCE TYPICAL SOURCE
T urbidity (NTU, highest detected measurement) TT = 1.0 NA 0.28 Yes Soil runoff T urbidity (lowest % of samples <0.3) TT = Minimum 95% of samples each month <0.3) NA 100.0 Yes Soil runoff Tap Water Samples Collected for Copper and Lead Analyses from Sample Sites throughout the Community in 2018

SUBSTANCE
(UNIT OF MEASURE) AL
PHG
(MCLG)
AMOUNT

DETECTED
(90TH%TILE)

SITES ABOVE

AL/ TOTAL
SITES
IN

COMPLIANCE TYPICAL SOURCE
Copper (ppm) 1.3 0.3 0.30 0/31 Yes Internal corrosion of household plumbing systems; erosion of natural deposits; leaching from wood preservatives
Lead (ppb) 15 0.2 ND 0/31 Yes Internal corrosion of household plumbing systems; erosion of natural deposits; leaching from wood preservatives

SECONDARY SUBSTANCES

SUBSTANCE
(UNIT OF MEASURE) SMCL
PHG
(MCLG) AVERAGE
RANGE

LOW-HIGH
IN

COMPLIANCE TYPICAL SOURCE
Chloride (ppm) 500 NS 22.1 7.8–65.9 Yes Runoff/leaching from natural deposits; seawater influence Specific Conductance (µS/cm) 1,600 NS 290 260–320 Yes Substances that form ions when in water; seawater influence Sulfate (ppm) 500 NS 49.5 41.0–58.0 Yes Runoff/leaching from natural deposits; industrial wastes T otal Dissolved Solids (ppm) 1,000 NS 300 186–550 Yes Runoff/leaching from natural deposits T urbidity (NTU) 5 NS 0.14 0.02–3.12 Yes Soil runoff
UNREGULATED SUBSTANCES 1

SUBSTANCE
(UNIT OF MEASURE)
AMOUNT

DETECTED
RANGE

LOW-HIGH TYPICAL SOURCE
Hardness, T otal [as CaCO3] (ppm) 96 71–120 Naturally occurring in ground- and surface water Sodium (ppm) 19 15–22 Naturally occurring in ground- and source water 1 Unregulated contaminant monitoring helps U.S.

EPA and the State Water Resources Control
Board determine where certain contaminants
occur and whether the contaminants need to be
regulated.

ATTACHMENT 1

Presented By
City of Napa
PWS ID#: 2810003Este informe contiene información muy importante sobre su agua potable. T radúzcalo o hable con alguien que lo entienda bien.

ATTACHMENT 1

Questions?
Quality First
W
e are once again pleased to present our annual water quality report covering all testing performed between January 1 and December 31, 2020. We dedicate ourselves to producing drinking water that meets all state and federal standards. We continually strive to adopt new methods for delivering the best-quality drinking water to you. As new challenges to drinking water safety emerge, we remain vigilant in meeting the goals of source water protection, water conservation, and community education while continuing to serve the needs of all our water users.

Please remember that we are always available should you ever have any questions or concerns about your water.

The City of Napa encourages citizens to participate in our City Council meetings, which take place on the first and third T uesday of each month from 3:30 - 5:00 p.m. and again from 6:30 - 9:00 p.m., in our Council Chambers at City Hall, 955 School Street. For more information concerning City activities, please see our website at https://www.cityofnapa.org.

Important Health Information
S
ome people may be more vulnerable to contaminants
in drinking water than the general population.

Immunocompromised persons such as those with cancer
undergoing chemotherapy, those who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly, and infants may be particularly at risk from infections. These people should seek advice about drinking water from their health care providers.

The U.S. EPA/CDC (Centers for Disease
Control and Prevention) guidelines on
appropriate means to lessen the risk of
infection by Cryptosporidium and other
microbial contaminants are available from
the Safe Drinking Water Hotline at (800)
426-4791 or http://water.epa.gov/
drink/hotline.

For more information about
this report, or for any questions
relating to your drinking water, please call Erin Kebbas, Water Quality Manager, at (707) 253-0822. For questions concerning the City of Napa Water Division, in general, please call (707) 257-9521. See our website for up-to-date information on programs: https://www.cityofnapa.org/water. For emergencies or customer use during weekends and holidays, please call (707) 253-4451.

Where Does My Water Come
From?
C
ity of Napa customers benefit from a
flexible water supply including three
different sources. Depending on which
treatment plant is in operation, the source
comes from: 1. Barker Slough in the Sacramento
Delta via the North Bay Aqueduct (treated by the
Edward I. Barwick Jamieson Canyon Water T reatment Plant);

2. Lake Hennessey (treated by the Hennessey Water T reatment Plant), or 3. Lake Milliken (treated by the Milliken Water T reatment Plant).

Protecting Our Watersheds
T
he City of Napa is devoted to protecting the
land surrounding our local source waters in
order to maintain the quality and purity of water
used for Napa’s drinking water consumers. In
the long term, protecting our watersheds is one
of the least costly and most important actions
we can take to reduce the risk of unwanted
constituents in our drinking water. Algal growth
due to the addition of nutrients is the number one
cause of taste and odor affecting your tap water.

Nutrients in the watershed are increased artificially
by wastewater systems as well as fertilizers and
runoff from agricultural practices. Every five
years, the City of Napa conducts Source Water
Assessments to evaluate the quality of the water
used as the drinking water supply and to examine
activities associated with the specific waterway and
surrounding areas to determine their contribution
to contamination.

These potential contributors are then compiled
into a Vulnerability Summary. Results from the
Vulnerability Summaries show that these are the
most significant potential sources of contaminants
for the City of Napa’s source waters:

Lake Hennessey (completed April 2018):

Pacific Union College Wastewater T reatment
Plant, vineyards, fires, invasive species, potential
hazardous material spills due to traffic accidents
(on Highway 128 near lake), septic tank systems
(in Angwin), and grazing and wild animals.

Lake Milliken (completed April 2018): Fires,
vineyards, and grazing and wild animals.

Sacramento Delta (updated 2017): Recreational
use, urban and agricultural runoff, grazing animals,
herbicide application, and seawater intrusion.

Copies of the complete assessments are available
through the SWRCB DDW Santa Rosa District
Office, 50 D Street, Suite 200, Santa Rosa, CA
95404 or Ms. Amy Little, Associate Sanitary
Engineer, SWRCB at (707) 576-2145.

ATTACHMENT 1

Lead in Home Plumbing
I
f present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. Unlike other regions of the U.S. where lead was prevalent, it was not the predominant construction material used in the City of Napa for water service installations. In addition, years of monitoring show that the existing public system pipe network does not contribute lead to our drinking water. Our next lead and copper collection is scheduled for July 2021. The City of Napa is responsible for providing high- quality drinking water, but we cannot control the variety of materials used in plumbing components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 minutes before using water for drinking or cooking. (If you do so, you may wish to collect the flushed water and reuse it for another beneficial purpose, such as watering plants.) If you are concerned about lead in your water, you may wish to have your water tested. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline at (800) 426-4791 or at www.epa.gov/safewater/lead.

Substances That Could Be in Water
T
he sources of drinking water (both tap water and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from human activity.

In order to ensure that tap water is safe to drink, the U.S. Environmental Protection Agency (U.S. EPA) and the State Water Resources Control Board (State Board) prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. The U.S. Food and Drug Administration regulations and California law also establish limits for contaminants in bottled water that provide the same protection for public health. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants.

The presence of contaminants does not necessarily indicate that water poses a health risk.

Contaminants that may be present in source water include:

Microbial Contaminants, such as viruses and bacteria, that may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife;
Inorganic Contaminants, such as salts and metals, that can be naturally occurring or can result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming; Pesticides and Herbicides, that may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses;
Organic Chemical Contaminants, including synthetic and volatile organic chemicals, that are by-products of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, agricultural applications, and septic systems;
Radioactive Contaminants, that can be naturally occurring or can be the result of oil and gas production and mining activities.

More information about contaminants and potential health effects can be obtained by calling the U.S. EPA’s Safe Drinking Water Hotline at (800) 426-4791.

ATTACHMENT 1

Count on Us
D
elivering high-quality drinking water to our customers
involves far more than just pushing water through pipes.

Water treatment is a complex, time-consuming process. Because tap water is highly regulated by state and federal laws, water treatment plant and system operators must be licensed and are required to commit to long-term, on-the-job training before becoming fully qualified. Our licensed water professionals' technical knowledge inclues a wide range of subjects, including mathematics, biology, chemistry, and physics. Some of the tasks they complete on a regular basis include:
• Operating and maintaining equipment to purify and clarify water;
• Monitoring and inspecting machinery, meters, gauges, and operating conditions;
• Conducting tests and inspections on water and evaluating the results;
• Maintaining optimal water chemistry;
• Applying data to formulas that determine treatment
requirements, flow levels, and finished water protection; • Documenting and reporting test results and system operations to regulatory agencies; and
• Serving our community through customer support,
education, and outreach.

So, the next time you turn on your faucet, think of the skilled professionals who stand behind each drop.

Protecting Your Water
B
acteria are a natural and important part of our world.

There are around 40 trillion bacteria living in each of us; without them, we would not be able to live healthy
lives. Coliform bacteria are common in the environment
and are generally not harmful themselves. The presence of this bacterial form in drinking water is a concern, however, because it indicates that the water may be contaminated with other organisms that can cause disease.

In 2016, the U.S. EPA passed a regulation called the
Revised T otal Coliform Rule, which requires additional steps that water systems must take in order to ensure
the integrity of the drinking water distribution system by monitoring for the presence of bacteria like total
coliform and E. coli. The rule requires more stringent
standards than the previous regulation, and it requires water systems that may be vulnerable to contamination to have in place procedures that will minimize the incidence of contamination. Water systems that exceed a specified frequency of total coliform occurrences are required to conduct an assessment of their system and correct any
problems quickly. The U.S. EPA anticipates greater public health protection under this regulation due to its more preventative approach to identifying and fixing problems that may affect public health.

The City of Napa was an early adopter of the Revised T otal Coliform Rule. Our strictly regulated water treatment
operation and distribution system maintenance ensures
the City of Napa consistently upholds a high standard of preventative actions to maintain public health.

T ap vs. Bottled
T
hanks in part to aggressive marketing, the bottled
water industry has successfully convinced us
all that water purchased in bottles is a
healthier alternative to tap water. However,
according to a four-year study conducted
by the Natural Resources Defense Council
(NRDC), bottled water is not necessarily
cleaner or safer than most tap water. In
fact, about 25 percent of bottled water is actually just bottled tap water.

The Food and Drug Administration is responsible for
regulating bottled water, but these rules allow for less rigorous testing and purity standards than those required by the U.S.

EPA for community tap water. For instance, the high mineral content of some bottled waters makes them unsuitable for babies and young children. Furthermore, the FDA completely exempts bottled water that’s packaged and sold within the same state, which accounts for about 70 percent of all bottled water sold in the United States.

People spend up to 10,000 times more per gallon for bottled water than they typically do for tap water. If you get your recommended eight glasses a day from bottled water, you could spend up to $1,400 annually. The same amount of tap water would cost less than a dollar.

Concerned about Taste & Odor?
Seasonally, you may experience taste and odor in your tap water associated with algae in our surface water. If you installed and properly maintained a granular activated carbon filter device on your tap, your annual expenditure would be far less than what you’d pay for bottled water.

For a detailed discussion on the NRDC study results, check out their Web site at https://www.NRDC.org/stories/truth- about-tap.

Water Conservation Tips
I
n a drought, you can play a role in conserving water
and save yourself money in the process. Become
aware of the amount of water your household is using
and look for simple ways to use less. Here are a few tips:
• Do laundry and dishes only when you have a full
load.
• T urn off the tap when brushing your teeth.
• Check every faucet in your home for leaks. Just a
slow drip can waste 15 to 20 gallons a day. Fix it
and you can save almost 6,000 gallons per year.
• Check your toilets for leaks by putting a few drops
of food coloring in the tank. Watch for a few
minutes to see if the color shows up in the bowl. It
is not uncommon to lose up to 100 gallons a day
from an invisible toilet leak. Fix it and you save
more than 30,000 gallons a year.
• Reduce your outdoor irrigation by one day per
week. This simple action will help us meet our
drought year goal of using 15% less water than
last year.

ATTACHMENT 1

T est Results
O
ur water is monitored for hundreds of different kinds of substances (including but not limited to metals or inorganic chemicals, volatile organic chemicals, man-made substances and disinfection by-products) on a very strict schedule and our goal is to keep any detections below their respective maximum allowed levels. Remember that detecting a substance does not mean the water is unsafe to drink. Here, in this report, we show only those substances that were detected in our water in 2020. Your water met all U.S. EPA and SWRCB standards in 2020 .

We participated in the 4th stage of the U.S. EPA’s Unregulated Contaminant Monitoring Rule (UCMR4) program by performing additional tests on our drinking water. UCMR4 sampling benefits the environment and public health by providing the EPA with data on the occurrence of contaminants suspected to be in drinking water, in order to determine if the EPA needs to introduce new regulatory standards to improve drinking water quality. Unregulated contaminant monitoring data are available to the public, so please feel free to contact us if you are interested in obtaining that information. If you would like more information on the U.S. EPA’s Unregulated Contaminant Monitoring Rule, please call the Safe Drinking Water Hotline at (800) 426-4791.

REGULATED SUBSTANCES

SUBSTANCE
(UNIT OF MEASURE)
MCL
[MRDL]
PHG
(MCLG)
[MRDLG]
AMOUNT

DETECTED
(LRAA) [RAA]
RANGE

LOW-HIGH
IN

COMPLIANCE TYPICAL SOURCE
Aluminum (ppm) 1 0.6 0.05 0.00–0.09 Yes Erosion of natural deposits; residue from some surface water treatment processes
Bromate (ppb) 10 0.1 [0.001] 0.000-0.002 Yes By-product of drinking water disinfection Chlorine (ppm) [4.0 (as Cl2)] [4.0 (as Cl2)] [0.89] 0.02–1.57 Yes Drinking water disinfectant added for treatment Control of DBP precursors [TOC]
(removal ratio)
TT NA [1.91] 1.24–2.69 Yes Various natural and man-made sources Haloacetic Acids (ppb) 60 NA (39.0) 0.0–51.9 Yes By-product of drinking water disinfection TTHMs [T otal Trihalomethanes] (ppb) 80 NA (67.9) 25.6–87.0 Yes By-product of drinking water disinfection T otal Coliform Bacteria (Positive samples) Maximum % of positive samples < 5.0
NA 2/1306 [0.15%] Highest monthly
% positive -

0.97%
Yes Naturally present in the environment
Filter Performance (Turbidity-the Standard Measure of Clarity in Water)

SUBSTANCE
(UNIT OF MEASURE) MCL PHG
AMOUNT

DETECTED
IN

COMPLIANCE TYPICAL SOURCE
T urbidity (NTU, highest detected measurement) TT NA 0.21 Yes Soil runoff T urbidity (Lowest monthly percent of samples meeting limit) TT = 95% of samples meet the limit NA 100.0 Yes Soil runoff Tap Water Samples Collected for Copper and Lead Analyses from Sample Sites throughout the Community in 2018

SUBSTANCE
(UNIT OF MEASURE) AL
PHG
(MCLG)

AMOUNT DETECTED
(90TH%TILE)

SITES ABOVE AL/

TOTAL SITES
IN

COMPLIANCE TYPICAL SOURCE
Copper (ppm) 1.3 0.3 0.3 0/31 Yes Internal corrosion of household plumbing systems; erosion of natural deposits; leaching from wood preservatives Lead (ppb) 15 0.2 ND 0/31 Yes Internal corrosion of household plumbing systems; erosion of natural deposits; leaching from wood preservatives

SECONDARY SUBSTANCES

SUBSTANCE (UNIT OF MEASURE) SMCL PHG (MCLG) AVERAGE RANGE LOW-HIGH IN COMPLIANCE TYPICAL SOURCE Chloride (ppm) 500 NS 13 11–15 Yes Runoff/leaching from natural deposits; seawater influence Specific Conductance (µS/cm) 1,600 NS 299 202–598 Yes Substances that form ions when in water; seawater influence Sulfate (ppm) 500 NS 48 48–48 Yes Runoff/leaching from natural deposits; industrial wastes T otal Dissolved Solids (ppm) 1,000 NS 274 196–457 Yes Runoff/leaching from natural deposits T urbidity (NTU) 5 NS 0.12 0.02–2.8 Yes Soil runoff
UNREGULATED SUBSTANCES 1

SUBSTANCE (UNIT OF MEASURE) AVERAGE RANGE LOW-HIGH TYPICAL SOURCE Hardness, T otal [as CaCO3] (ppm) 105 63–162 Naturally occurring in groundwater and surface water Sodium (ppm) 19 13–24 Naturally occurring in groundwater and surface water 1 Unregulated contaminant monitoring helps the U.S. EPA and the State Water Resources Control Board to determine where certain contaminants occur and whether the contaminants need to be regulated.

ATTACHMENT 1

Definitions
90th %ile: The levels reported for lead and copper represent the 90th percentile of the total number of sites tested. The 90th percentile is equal to or greater than 90% of our lead and copper detections.

AL (Regulatory Action Level): The concentration of a contaminant that, if exceeded, triggers treatment or other requirements that a water system must follow. µS/cm (microsiemens per centimeter): A unit expressing the amount of electrical conductivity of a solution.

DBP: Disinfection By Product
LRAA (Locational Running Annual Average): The average of sample analytical results for samples taken at a particular monitoring location during the previous four calendar quarters. Amount Detected values for TTHMs and HAAs are reported as the highest LRAAs.

MCL (Maximum Contaminant Level): The highest level of a contaminant that is allowed in drinking water. Primary MCLs are set as close to the PHGs (or MCLGs) as is economically and technologically feasible. Secondary MCLs (SMCLs) are set to protect the odor, taste, and appearance of drinking water.

MCLG (Maximum Contaminant Level Goal): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs are set by the U.S. EPA.

MRDL (Maximum Residual Disinfectant Level): The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

MRDLG (Maximum Residual Disinfectant Level Goal): The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

NA: Not applicable
NS: No standard
NTU (Nephelometric T urbidity Units): Measurement of the clarity, or turbidity, of water. T urbidity in excess of 5 NTU is just noticeable to the average person.

PDWS (Primary Drinking Water Standard): MCLs and MRDLs for contaminants that affect health along with their monitoring and reporting requirements, and water treatment requirements.

PHG (Public Health Goal): The level of a contaminant in drinking water below which there is no known or expected risk to health. PHGs are set by the California EPA. ppb (parts per billion): One part substance per billion parts water (or micrograms per liter). ppm (parts per million): One part substance per million parts water (or milligrams per liter). removal ratio: A ratio between the percentage of a substance actually removed to the percentage of the substance required to be removed.

TOC: T otal Organic Carbon
TT (Treatment T echnique): A required process intended to reduce the level of a contaminant in drinking water.

T o the Last Drop
T
he National Oceanic and Atmospheric Administration (NOAA) defines drought as a deficiency in precipitation over an extended period of time, usually a season or more, resulting in a water shortage causing adverse impacts on vegetation, animals, and/or people. Drought strikes in virtually all climate zones, from very wet to very dry.

The winter rains of 2020 did not replenish Lake Hennessey, our largest local surface water supply reservoir. We received under 10 inches of rain, significantly less than our 27-inch average. This drought year requires we reduce our summer time outdoor irrigation by 15%.

Drought is a temporary aberration from normal climatic conditions; thus it can vary significantly from one region to another. Although drought occurs normally, human factors, such as water demand, can exacerbate the duration and impact that drought has on a region. By following simple water conservation measures, you can help significantly reduce the lasting effects of extended drought.

ATTACHMENT 1

Presented By
City of Napa
PWS ID#: 2810003
Este informe contiene información muy importante sobre su agua potable. T radúzcalo o hable con alguien que lo entienda bien.

ATTACHMENT 1

Questions?
Important Health Information
S
ome people may be more vulnerable to contaminants
in drinking water than the general population.

Immunocompromised persons such as persons with cancer
undergoing chemotherapy, persons who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly, and infants may be particularly at risk from infections. These people should seek
advice about drinking water from their health
care providers. The U.S. EPA/CDC (Centers
for Disease Control and Prevention) guidelines
on appropriate means to lessen the risk of
infection by Cryptosporidium and
other microbial contaminants
are available from the Safe
Drinking Water Hotline at
(800) 426-4791 or http://
water.epa.gov/drink/hotline.

For more information about this
report, or for any questions relating
to your drinking water, please call Erin Kebbas, Water Quality Manager, at (707) 253-0822. For questions concerning the City of Napa Water Division in general, please call (707) 257- 9521. See our website, cityofnapa.org/water, for up-to-date information on programs. For emergencies or customer use during weekends and holidays, please call (707) 253-4451.

Our Mission Continues
O
nce again, we are proud to present our annual water quality report covering the period between January 1 and December 31, 2021. Our exceptional staff continues to work hard every day—at all hours—to deliver the highest-quality drinking water without interruption. Although the challenges ahead are many, we feel that by relentlessly investing in customer outreach and education, new treatment technologies, system upgrades, and training, the payoff will be continued, safe, reliable, high-quality tap water delivered to you and your family.

Times of Drought
T
his current drought will require a multi-year recovery.

The City of Napa has invested in water supplies to
ensure a reliable water supply for you, our customers. Our two local surface water reservoirs: Lake Hennessey and
Milliken Reservoir are important investments made by
citizens of Napa in 1948 and 1923, respectively. In addition, Napa secured a connection to the State Water Project (SWP) in 1968. In a given year, when local supplies are low, the City can rely on the larger, regional system until our local supplies replenish. In the 2014-2015 drought this strategy worked perfectly. In addition, Lake Hennessey filled and spilled at the start of the drought.

The current drought has affected both local and regional watersheds. During the winter of 2020-2021 Lake Hennessey accrued only 9-inches of rain, well below the 27-inch
average, resulting in just 2,000 AF of recharge, matching the lowest amount on record received in 1977. The major storage in the SWP system was just 24% of average and the 3rd driest on record. Drought brings obvious challenges to our water quantity, and the uncertainty of availability in the years to come.

Did You Know That Drought Can Also Bring
Challenges to Water Quality?
The recharge and replenishment of water in our creeks,
streams, and reservoirs clears the lands of natural (trees, leaves, etc.) and man-made (fertilizers, litter, etc.) constituents that build up on surfaces each year. In drought years, due to lack of rainfall, water does not flow sufficiently to enact the annual cleanse of the lands. Eventually large storms, such as the deluge we received in late October, flush and clear the land surface, which in late 2021, effectively cleared two years of buildup. Compounding the drought situation, the watersheds in the SWP system were affected by fires, including thousands of acres burned in the Dixie fire. Post-fire runoff affects water quality by increasing contaminants that are washed into the waterways. Our water treatment process is effective in removing these contaminants to meet regulatory requirements. The ozone process
added to the Barwick Jamieson
T reatment Plant in 2011
has been instrumental
in addressing these
seasonal challenges.

Where Does My Water Come From?
T
he City of Napa’s customers are
fortunate because we have water
supply from three sources. Depending
on which water treatment plant is in
operation, the sources are (1) Barker
Slough in the Sacramento Delta
via the North Bay Aqueduct, treated
by the Edward I. Barwick Jamieson
Canyon Water T reatment Plant; (2) Lake
Hennessey, treated by the Hennessey
Water T reatment Plant; or (3) Lake
Milliken, treated by the Milliken Water
T reatment Plant.

ATTACHMENT 1

Substances That Could Be in Water
T
he sources of drinking water (both tap water
and bottled water) include rivers, lakes, streams,
ponds, reservoirs, springs, and wells. As water travels over the surface of the land or through the ground,
it dissolves naturally occurring minerals and, in some
cases, radioactive material, and can pick up substances resulting from the presence of animals or from human
activity.

In order to ensure that tap water is safe to drink, the U.S. Environmental Protection Agency (U.S. EPA)
and the State Water Resources Control Board (State
Board) prescribe regulations that limit the amount of
certain contaminants in water provided by public water
systems. The U.S. Food and Drug Administration
regulations and California law also establish limits for contaminants in bottled water that provide the same
protection for public health. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence
of contaminants does not necessarily indicate that water poses a health risk.

Contaminants that may be present in source water
include:

Microbial Contaminants, such as viruses and bacteria,
that may come from sewage treatment plants, septic
systems, agricultural livestock operations, and wildlife; Inorganic Contaminants, such as salts and metals, that
can be naturally occurring or can result from urban
stormwater runoff, industrial or domestic wastewater
discharges, oil and gas production, mining, or farming; Pesticides and Herbicides, that may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses;
Organic Chemical Contaminants, including synthetic
and volatile organic chemicals, which are by-products
of industrial processes and petroleum production, and
which can also come from gas stations, urban stormwater runoff, agricultural applications, and septic systems;
Radioactive Contaminants that can be naturally
occurring or can be the result of oil and gas production and mining activities.

More information about contaminants and potential
health effects can be obtained by calling the U.S. EPA’s Safe Drinking Water Hotline at (800) 426-4791.

Lead in Home Plumbing
F
ortunately, before it was banned by the EPA in 1986,
lead was not a common material used for service pipes in the City of Napa. If present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. We are responsible for providing high-quality drinking water, but we cannot control the variety of materials used in plumbing components. When your water has been
sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to two minutes before using water for drinking or cooking. (If you do so, you may wish to collect the flushed water and reuse it for another beneficial purpose, such as watering plants.) If you are concerned about lead in your water, you may wish to have your water tested. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline at (800) 426-4791 or at www.epa.gov/safewater/lead.

Community Participation
T
he City of Napa encourages citizens to
participate in our city council meetings, which
take place on the first and third T uesday of each
month from 3:30 to 5:00 p.m. and again at 6:30 to
9:00 p.m. in Council Chambers at City Hall, 955
School Street. For more information concerning city
activities, please see our website at cityofnapa.org.

Protecting Our Watershed
T
he City of Napa is devoted to protecting the land
surrounding our local source waters in order to maintain the quality and purity of water used for Napa’s drinking water consumers. In the long term, protecting our watershed is one of the least costly and most important actions we can take to reduce the risk of unwanted constituents in our drinking water. Algal growth due to the presence of nutrients is the number one cause of taste and odor affecting your tap water. Nutrients in the watershed are increased artificially by wastewater systems as well as fertilizers and runoff from agricultural practices.

Water Conservation Tips
Y
ou can play a role in conserving water and save yourself money in the process by becoming conscious of the
amount of water your household is using and looking for ways to use less whenever you can. It’s not hard to conserve water.

Here are a few tips:
• Automatic dishwashers use 15 gallons for every cycle, regardless of how many dishes are loaded. So get a run for your money and load it to capacity.
• T urn off the tap when brushing your teeth.
• Check every faucet in your home for leaks. Just a slow drip can waste 15 to 20 gallons a day. Fix it and you can save almost 6,000 gallons per year.
• Check your toilets for leaks by putting a few drops of food coloring in the tank. Watch for a few minutes to see if the color shows up in the bowl. It is not uncommon to lose
up to 100 gallons a day from an invisible toilet leak. Fix it and you save more than 30,000 gallons a year.
• Use your water meter to detect hidden leaks. Simply turn off all taps and water-using appliances. Then check the meter after 15 minutes. If it moved, you have a leak.
• Implement water efficient landscaping. City of Napa pays you $1/ft2 to replace thirsty turf and $2/ft2 to Flip the Strip.

Program details can be found at Cash For Grass | Napa, CA (cityofnapa.org)
ATTACHMENT 1

T est Results
O
ur water is monitored for many different kinds of substances on a very strict sampling schedule, and the water we deliver must meet specific health standards. Here, we only show those substances that were detected in our water (a complete list of all our analytical results is available upon request). Remember that detecting a substance does not mean the water is unsafe to drink; our charge is to keep all detections below their respective maximum allowed levels.

The state recommends monitoring for certain substances less than once per year because the concentrations of these substances do not change frequently. In these cases, the most recent sample data are included, along with the year in which the sample was taken. Your water met all U.S. EPA and State Board standards in 2021.

REGULATED SUBSTANCES

SUBSTANCE
(UNIT OF MEASURE)
MCL
[MRDL]
PHG
(MCLG)
[MRDLG]
AMOUNT

DETECTED
(LRAA) [RAA]
RANGE

LOW-HIGH
IN

COMPLIANCE TYPICAL SOURCE
Aluminum (ppm) 1 0.6 0.08 0.06–0.09 Yes Erosion of natural deposits; residue from some surface water treatment processes
Bromate (ppb) 10 0.1 [0.001] ND–0.001 Yes By-product of drinking water disinfection Chlorine (ppm) [4.0 (as Cl₂)] [4.0 (as Cl₂)] [0.63] ND–1.53 Yes Drinking water disinfectant added for treatment Control of DBP Precursors [TOC] (removal ratio) TT NA [1.90] 1–2.87 Yes Various natural and human-made sources HAA5 [Sum of 5 Haloacetic Acids]–Stage 2 (ppb) 60 NA (30.9) ND–32 Yes By-product of drinking water disinfection TTHMs [T otal Trihalomethanes]–Stage 21 (ppb) 80 NA (65.4) 17.8–91.1 Yes By-product of drinking water disinfection Tap water samples were collected for lead and copper analyses from sample sites throughout the community in 2021

SUBSTANCE
(UNIT OF MEASURE) AL
PHG
(MCLG)

AMOUNT DETECTED
(90TH %ILE)

SITES ABOVE AL/

TOTAL SITES IN COMPLIANCE TYPICAL SOURCE
Copper (ppm) 1.3 0.3 0.33 0/34 Yes Internal corrosion of household plumbing systems; erosion of natural deposits; leaching from wood preservatives
Lead (ppb) 15 0.2 ND 0/34 Yes Internal corrosion of household water plumbing systems; discharges from industrial manufacturers; erosion of natural deposits

SECONDARY SUBSTANCES

SUBSTANCE (UNIT OF MEASURE) SMCL PHG (MCLG) AVERAGE RANGE LOW-HIGH IN COMPLIANCE TYPICAL SOURCE Chloride (ppm) 500 NS 18 11–34 Yes Runoff/leaching from natural deposits; seawater influence Specific Conductance (µS/cm) 1,600 NS 315 223–434 Yes Substances that form ions when in water; seawater influence Sulfate (ppm) 500 NS 57 45–68 Yes Runoff/leaching from natural deposits; industrial wastes T otal Dissolved Solids (ppm) 1,000 NS 284 139–391 Yes Runoff/leaching from natural deposits T urbidity (NTU) 5 NS 0.08 0.02–0.59 Yes Soil runoff
UNREGULATED SUBSTANCES 2

SUBSTANCE (UNIT OF MEASURE) AVERAGE RANGE LOW-HIGH TYPICAL SOURCE Hardness, T otal [as CaCO3] (ppm) 98 39–177 Naturally occurring in groundwater and surface water Sodium (ppm) 24 17–30 Naturally occurring in groundwater and surface water Filter Performance (Turbidity-the Standard Measure of Clarity in Water)

SUBSTANCE (UNIT OF MEASURE, HIGHEST DETECTED MEASUREMENT) MCL PHG AMOUNT DETECTED IN COMPLIANCE TYPICAL SOURCE T urbidity (NTU) TT NA 1.02 Yes Soil runoff
T urbidity (Lowest monthly percent of samples meeting limit) TT = 95% of samples meet the limit NA 100% Yes Soil runoff 1 Some people who drink water containing trihalomethanes in excess of the MCL over many years may experience problems with their liver, kidneys, or central nervous system and may have an increased risk of getting cancer. 2 Unregulated contaminant monitoring helps U.S. EPA and the State Water Resources Control Board determine where certain contaminants occur and whether the contaminants need to be regulated.

ATTACHMENT 1

Definitions
90th %ile: The levels reported for lead and copper represent the 90th percentile of the total number of sites tested. The 90th percentile is equal to or greater than 90% of our lead and copper detections.

AL (Regulatory Action Level): The concentration of a contaminant which, if exceeded, triggers treatment or other requirements that a water system must follow.

MCL (Maximum Contaminant Level): The highest level of a contaminant that is allowed in drinking water. Primary MCLs are set as close to the PHGs (or MCLGs) as is economically and technologically feasible. Secondary MCLs (SMCLs) are set to protect the odor, taste, and appearance of drinking water.

MCLG (Maximum Contaminant Level Goal): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs are set by the U.S. EPA.

MRDL (Maximum Residual Disinfectant Level): The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

MRDLG (Maximum Residual Disinfectant Level Goal): The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

NA: Not applicable.

ND (Not detected): Indicates that the substance was not found by laboratory analysis.

NS: No standard.

NTU (Nephelometric T urbidity Units): Measurement of the clarity, or turbidity, of water. T urbidity in excess of 5 NTU is just noticeable to the average person.

PDWS (Primary Drinking Water Standard): MCLs and MRDLs for contaminants that affect health, along with their monitoring and reporting requirements and water treatment requirements.

PHG (Public Health Goal): The level of a contaminant in drinking water below which there is no known or expected risk to health. PHGs are set by the California EPA. ppb (parts per billion): One part substance per billion parts water (or micrograms per liter). ppm (parts per million): One part substance per million parts water (or milligrams per liter). removal ratio: A ratio between the percentage of a substance actually removed to the percentage of the substance required to be removed.

TT (Treatment T echnique): A required process intended to reduce the level of a contaminant in drinking water.
µS/cm (microsiemens per centimeter): A unit expressing the amount of electrical conductivity of a solution.

Source Water Assessments
E
very five years, the City of Napa conducts source water assessments to evaluate the quality of the water used as drinking water supply and examine activities associated with the specific waterway and surrounding areas to determine their contribution to contamination. These potential contributors are then compiled into a Vulnerability Summary. Results from the Vulnerability Summaries show the most significant potential sources of contaminants for the City of Napa’s source waters are:

Lake Hennessey (completed April 2018): Pacific Union
College Wastewater T reatment Plant, vineyards, fires, invasive species, potential hazardous material spills due to traffic accidents (on Highway 128 near lake), septic tank systems (in Angwin), grazing, and wild animals.

Lake Milliken (completed April 2018): Fires, vineyards, grazing, and wild
animals.

Sacramento Delta
(updated 2017):

Recreational use, urban
and agricultural runoff,
grazing animals,
herbicide application,
and seawater intrusion.

Copies of the complete
assessments are
available through the
SWRCB DDW Santa
Rosa District Office,
50 D Street, Suite 200,
Santa Rosa, CA 95404,
or by calling SWRCB
at (707) 576-2145.

ATTACHMENT 1