CONTRA COSTA WATER DISTRICT

Erin Gomez | 925-688-8091

CITY OF ANTICOH

Laura Villasana | 925-779-7024

CITY OF MARTINEZ

Hiren Patel | 925-372-3588

CITY OF PITTSBURG

Ana Corti | 925-252-6916

DIABLO WATER DISTRICT

Nacho Mendoza | 925-625-2112

GOLDEN STATE WATER COMPANY (BAY POINT)

800-999-4033

CITY OF BRENTWOOD

James Wolfe | 925-516-6000

TO OUR CUSTOMERS:

We are pleased to present the Annual Water Quality Report that shows the high quality of your drinking water. As the water providers to more than 500,000 people, you can count on us to provide a reliable product that exceeds all drinking water standards set by the state and federal governments keeping our community healthy and thriving. We wisely put your water dollars to work investing in the systems and infrastructure that deliver a reliable supply of high-quality water at the lowest cost possible. This report includes water quality data collected throughout 2020 and answers questions you might have about your tap water. For detailed test results, see pages 7-11.

You can be confident your tap water is of a high quality that is always there for you. Frequent testing for water quality and regular improvements in the treatment process keeps your drinking water among the best in the country.

We hope you find this report useful in illustrating the high quality of your water service. If you have questions about the tap water in your community, please use the list on the left to call your water provider.

The 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.

CONTAMINANTS THAT MAY BE PRESENT IN SOURCE WATER

Microbial contaminants include viruses and bacteria, that may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.

Inorganic contaminants include salts and metals that can be naturally-occurring or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining or farming.

Organic chemical contaminants include synthetic and volatile organic chemicals that are byproducts of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, agricultural application and septic systems.

Pesticides and herbicides may come from a variety of sources, such as agriculture, urban stormwater runoff and residential uses.

Radioactive contaminants can be naturally occurring or be the result of oil and gas production and mining activities.

In order to ensure that tap water is safe to drink, the U.S. Environmental Protection Agency (US 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. State Board regulations 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. More information about contaminants and potential health effects can be obtained by calling the US EPA’s Safe Drinking Water Hotline (1-800-426-4791).

None of the public water systems listed in this report produce or distribute bottled water. The State Division of Drinking Water mandates that the statements about bottled water be included in this report.

Your drinking water is continually sampled and analyzed. We perform tens of thousands of tests throughout the year to ensure your water is clean and safe to use.

IMPORTANT NOTICE

Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno- compromised 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 can be particularly at risk from infections. These people should seek advice about drinking water from their health care providers. USEPA/Centers for Disease Control (CDC) 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 1-800-426-4791.

WATER QUALITY NOTIFICATIONS

LEAD IN DRINKING WATER

No water provider included in this report detected lead above the regulatory action level in their water supply. 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 plumbing in buildings and homes. Your drinking water supplier is responsible for providing high quality drinking water, but 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 1-800-426-4791 or at epa.gov/lead.

LEAD MONITORING IN SCHOOLS

In early 2017, the State Board issued amendments to domestic water supply permits of community water systems so that kindergarten through 12th grade (K–12) schools can request assistance from their water provider to conduct water sampling for lead and receive technical assistance if an elevated lead sample is found. To further safeguard water quality in California’s K–12 public schools, California Assembly Bill 746, effective January 1, 2018, requires community water systems to test lead levels, by July 1, 2019, in drinking water at all California public K–12 schools, preschools, and child care facilities located on public school property constructed before January 1, 2010.

To find out more about the Lead Sampling of Drinking Water in Schools initiative, visit waterboards.ca.gov/drinking_water/ certlic/drinkingwater/leadsamplinginschools.shtml.

The use of ozone disinfection results in drinking water that is very safe, with little taste and odor. Ozone effectively destroys potentially harmful microorganisms and, by breaking up the organic material often found in water, vastly improves the taste and odor of drinking water. In addition, ozone disinfection reduces the formation of many disinfection byproducts, such as trihalomethanes, a class of suspected cancer-causing compounds associated with chlorine disinfection.

FLUORIDE

To prevent tooth decay, fluoride is added to your drinking water. This is a long-standing practice that has improved public health over many years. To read about fluoridation, visit waterboards.ca.gov/drinking_water/certlic/drinkingwater/ Fluoridation.shtml.

Sedimentation basins in our water

treatment plants skim clean water from the top of the basin and allow heavy

organics to settle out at the bottom.

CRYPTOSPORIDIUM

Cryptosporidium is a microbial pathogen found in surface water throughout the U.S.

Although filtration removes Cryptosporidium, the most commonly-used filtration methods cannot

guarantee 100 percent removal. Our monitoring indicates the presence of these organisms in our source

water and/or finished water. Current test methods do not allow us to determine if the organisms are dead or if they are capable of causing disease. Ingestion of Cryptosporidium may

cause cryptosporidiosis, an abdominal infection. Symptoms of infection include nausea, diarrhea, and abdominal cramps. Most healthy individuals can overcome the disease within a few weeks. However, immunocompromised people, infants and small children, and the elderly are at greater risk of developing life-threatening illness. We encourage immuno-compromised individuals to consult their doctor regarding appropriate precautions to take to avoid infection. Cryptosporidium must be ingested to cause disease, and it may be spread through means other than drinking water.

THE SOURCE OF YOUR WATER

Nearly every drop of water delivered by Contra Costa Water District originates in the Sacramento-San Joaquin River Delta. Though Delta water quality fluctuates throughout the year, investments made by your water provider ensures the water delivered to your tap is of a consistent high-quality. Contra Costa Water District diverts water from four locations in the Delta and adjusts its operations to divert where water quality is best.

CONTRA COSTA WATER DISTRICT

CCWD provides treated drinking water to homes and businesses in Clayton, Clyde, Concord, Pacheco, Port Costa, and parts of Martinez, Pleasant Hill and Walnut Creek. Water is pumped from the Delta, treated and then delivered to customers through a network of distribution pipes.

CCWD completes watershed sanitary surveys every five years and the last one was completed in 2020. The surveys concluded that potential contamination is regularly mitigated by the natural flushing of the Delta, controls at contamination sources and existing water treatment practices.

In June 2002 and May 2003, source water assessments were conducted at the Old River, Rock Slough and Mallard Slough intakes, the Los Vaqueros, Contra Loma, Mallard and Martinez reservoirs, and the Contra Costa Canal at Clyde. A source water assessment was conducted for the Middle River Intake in 2012.

The assessments were based on a review of data collected from 1996 through 2001, as well as a review of the activities and facilities located at or near each source. In summary:

• Intakes were found to be most vulnerable to the effects of saltwater intrusion, agricultural drainage, recreational boating and regulated point discharges.
• Reservoirs were found to be most vulnerable to the effects of associated recreation, roads and parking lots, and watershed runoff.
• Contra Costa Canal was found to be most vulnerable to gas stations, chemical/petroleum processing/storage, septic systems, historic landfills and military institutions.

BAY POINT

The Golden State Water Company (GSWC) purchases treated water from CCWD and delivers it to customers through its distribution pipes. Water quality information for GSWC is not included in this report. View its water quality report at gswater.com/baypointccr.

BRENTWOOD

CCWD operates the CCWD/City of Brentwood’s water treatment plant to treat water for the City. Water quality information for Brentwood is not included in this report. View its water quality report at brentwoodca.gov/gov/pw/water/reports.asp.

Walnut Creek

24

680

Contra Costa Water District Boundary

Contra Costa Canal

Multi-Purpose Pipeline

Los Vaqueros Pipeline

Shortcut Pipeline

PITTSBURG

160 DIABLO

4WATER DISTRICT

LOS

VAQUEROS

RESERVOIR

DELTA

ROCK

SLOUGH

INTAKE

Discovery

Bay

4

J4CLIFTON

COURT

FOREBAY

DEFINITIONS & ABBREVIATIONS

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

Maximum Contaminant Level (MCL) – 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 or technologically feasible

Maximum Contaminant Level Goal (MCLG) – 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. Environmental Protection Agency

Maximum Residual Disinfectant Level (MRDL) –

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

Maximum Residual Disinfectant Level Goal (MRDLG) – 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

mg/L – Milligrams per liter

n/a – Not analyzed or not applicable (when used in average column, only one data point is available)

ND – Not detected at or above the reporting level ng/L – Nanograms per liter

NTU – Nephelometric turbidity units

Primary Drinking Water Standards – MCLs and MRDLs for contaminants that affect health along with their monitoring and reporting requirements, and water treatment requirements

pCi/L – Picocuries per liter (a measure of radioactivity)

Public Health Goal (PHG) – 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 Environmental Protection Agency Office of Health and Hazard Assessment

RAA – Running Annual Average

Secondary Drinking Water Standards – Secondary MCLs are set for contaminants that affect the odor, taste or appearance of water

Treatment Technique (TT) – A required process intended to reduce the level of a contaminant in drinking water

µg/L – Micrograms per liter

µmhos/cm– micromhos per centimeter (a measure of conductivity)

HOW TO READ THE TABLES

The following tables contain detailed information about the water that is delivered to your home or business. Your water is regularly tested for more than 120 chemicals and substances, as well as radioactivity. Only those constituents that were detected in 2020 are listed in the tables.

Constituents may vary from provider to provider depending on water source and treatment techniques. Please see ccwater.com for a list of constituents tested but not detected.

WATER

PROVIDER

PRIMARY DRINKING WATER STANDARDS Contaminants that may affect health

1. State or Federal Goal (PHG, MCLG or MRDLG) – The level of contaminant in drinking water below which there is no known or expected risk to health
2. Highest Amount Allowed (AL, MCL or MRDL) – The highest level of a contaminant that is allowed in drinking water
3. Average – The average level of a detected contaminant in drinking water
4. Major Source in Drinking Water – The most likely way a contaminant enters drinking water

SOURCE OF WATER

The City of Antioch purchases untreated water from CCWD, treats it in

a City-owned treatment

TABLE OF CHEMICALS OR CONSTITUENTS DETECTED IN WATER IN 2020

CITY OF

ANTIOCH

PRIMARY DRINKING WATER STANDARDS Contaminants that may affect health

plant and delivers it to customers through the City’s distribution pipes. The City is also able to pump directly from the San Joaquin River or purchase treated water from CCWD.

The City completes watershed sanitary surveys every five years. The last survey, completed in 2018, concluded that potential contamination is regularly mitigated by the natural flushing of the Delta, controls at contamination

Inorganic

Fluoride (mg/L)

Lead and Copper

Lead (µg/L)

Copper (mg/L)

Date of sampling

Microbiological Standards

Turbidity (NTU) (treatment plant)

Disinfectant/Disinfection Byproducts

Chloramines as CI2 (mg/L)

Haloacetic acids (µg/L)

Total trihalomethanes (µg/L)

State or

Federal Goal

1

State or

Federal Goal

0.2

0.3

State or

Federal Goal

n/a

State or

Federal Goal

n/a

n/a

sources and existing water

SECONDARY DRINKING WATER STANDARDS Contaminants that may affect the odor, taste or appearance of water

treatment practices.

In April 2003, Antioch conducted a source water assessment. In summary:

Chloride (mg/L)

Odor-threshold (units)

Specific conductivity (µmhos/cm)

Sulfate (mg/L)

Total dissolved solids (mg/L)

Turbidity (NTU)

(distribution system)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

Highest Amt.

Allowed

n/a

3

900

250

500

5

Range

Detected

31–111

1–2

336–630

48–58

142–382

0.03–0.78

Average

70

2

490

53

294

0.06

Major Source in Drinking Water

Runoff/leaching from natural deposits; seawater influence

Naturally-occurring organic materials

Substances that form ions when in water; seawater influence

Naturally-occurring organic materials

Runoff/leaching from natural deposits

Soil runoff

GENERAL WATER QUALITY PARAMETERS

Alkalinity (mg/L)

Calcium (mg/L)

Hardness (mg/L)

Magnesium (mg/L)

pH

Potassium (mg/L)

Sodium (mg/L)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Highest Amt.

Allowed

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Range

Detected

61–109

12–34

71–128

11–12

7.9–9.4

2–3

52–65

Average

80

18

94

12

8.6

2.5

59

PUBLIC MEETINGS

Second and Fourth Tuesdays 7:00 p.m.

200 H Street Antioch, CA 94509

925-779-7009 ci.antioch.ca.us

UCMR4 ASSESSMENT MONITORING 2018–2020

Water from the San Joaquin River is not always acceptable due to saltwater intrusion. When chloride levels in the river exceed 250 milligrams per liter, the City stops pumping until chloride levels decrease.

Manganese (µg/L)

HAA5 (µg/L)

HAA Br (µg/L)

HAA9 (µg/L)

Total Organic Carbon (TOC) (µg/L)

Bromide (µg/L)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

Notification

Level

500

n/a

n/a

n/a

n/a

n/a

Range

Detected

1.0–7.8

1.7–12

0.7–12

2.4–21

2,500–

3,900

130–360

Average

3.6

4.8

5.2

8.9

3,200

238

If you have any questions about the City of Antioch tap water, please call 925-779-7024.

CITY OF MARTINEZ

TABLE OF CHEMICALS OR CONSTITUENTS DETECTED IN WATER IN 2020

CITY OF

MARTINEZ

PRIMARY DRINKING WATER STANDARDS Contaminants that may affect health

SOURCE OF WATER

The City of Martinez purchases untreated water from CCWD, treats it in a City-owned

Inorganic

Fluoride (mg/L)

Nitrate as N (mg/L)

Lead and Copper

Lead (µg/L)

Copper (mg/L)

Date of sampling

Microbiological Standards

Turbidity (NTU) (treatment plant)

Disinfectant/Disinfection Byproducts

Chloramines as CI2 (mg/L)

Haloacetic acids (µg/L)

Total trihalomethanes (µg/L)

State or

Federal Goal

1

10

State or

Federal Goal

0.2

0.3

State or

Federal Goal

n/a

State or

Federal Goal

n/a

n/a

Highest Amt.

Allowed

2

10

Highest Amt.

Allowed

15

1.3

Highest Amt.

Allowed

95% ≤ 0.3

Highest Amt.

Allowed

4

60

80

treatment plant and delivers it through the City’s distribution pipes to customers who are not served treated water directly from CCWD.

Chloride (mg/L)

Odor-threshold (units)

Specific conductivity (µmhos/cm)

Sulfate (mg/L)

Total dissolved solids (mg/L)

Turbidity (NTU)

(distribution system)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

Highest Amt.

Allowed

250

3

900

250

500

5

Range

Detected

38–75

ND–1

360–490

48–51

190–290

0.2–0.4

Average

57

1

425

50

240

0.3

Major Source in Drinking Water

Runoff/leaching from natural deposits; seawater influence

Naturally-occurring organic materials

Substances that form ions when in water; seawater influence

Naturally-occurring organic materials

Runoff/leaching from natural deposits

Soil runoff

Alkalinity (mg/L)

Bromide (mg/L)

Calcium (mg/L)

Hardness (mg/L) Magnesium (mg/L) pH

Potassium (mg/L) Sodium (mg/L)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Highest Amt.

Allowed

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Range

Detected

63–64

0.1–0.3

14–16

72–85

9–11

8.4–9.3

1.9–3.0

43–58

Average

64

0.2

15

79

10

9.0

2.5

51

PUBLIC MEETINGS

First and Third Wednesdays 7:00 p.m.

525 Henrietta Street Martinez, CA 94553

925-372-2512 cityofmartinez.org

UCMR4 ASSESSMENT MONITORING 2018–2020

If you have any questions about

Manganese (µg/L)

HAA5 (µg/L)

HAA Br (µg/L)

HAA9 (µg/L)

Total Organic Carbon (TOC) (µg/L)

Bromide (µg/L)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

Notification

Level

500

n/a

n/a

n/a

n/a

n/a

Range

Detected

0.4–5.0

0.3–4.4

0.6–5.1

1.0–7.1

2,800–

4,400

110–310

Average

3.1

2.4

2.7

3.8

3,667

227

the City of Martinez tap water, please call 925-372-3588.

SOURCE OF WATER

The City of Pittsburg purchases untreated water from CCWD, treats it in

a City-owned treatment plant and delivers it to customers through the City’s distribution pipes. In addition to the water it buys from CCWD, the City is able to pump water from two wells.

A source water assessment was conducted for the Dover Well in September 2015, and for Bodega Well in July 2009. In summary:

• Bodega well was found to be most vulnerable to residential sewer collection systems, abandoned military installation (Camp Stoneman) and illegal activities (drug labs).
• Dover well was considered most vulnerable to sewer collection systems, transportation corridors, and storm drain discharge points. No contaminants associated with the identified potentially contaminating activities (PCA) have been detected in water samples from Dover well.

TABLE OF CHEMICALS OR CONSTITUENTS DETECTED IN WATER IN 2020

CITY OF

PITTSBURG

PRIMARY DRINKING WATER STANDARDS Contaminants that may affect health

TABLE OF CHEMICALS OR CONSTITUENTS DETECTED IN WATER IN 2020

SECONDARY DRINKING WATER STANDARDS Contaminants that may affect the odor, taste or appearance of water

SOURCE OF WATER

Diablo Water District purchases untreated water from CCWD. Water is treated and blended with groundwater pumped from two wells. The treated water is then delivered

to customers through its distributions pipes.

A source water assessment was conducted for the Glen Park well in April 2005 and for Stonecreek well in March 2011. In summary:

• Both wells were found to be most vulnerable to historic waste dumps/ landfills and septic systems (high density, >1/acre). These activities are not associated with contaminants in the water supply.

Chloride (mg/L)

Manganese (µg/L) Specific conductivity (µmhos/cm)

Sulfate (mg/L)

Total dissolved solids (mg/L)

Turbidity (NTU)

(distribution system)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

Highest Amt.

Allowed

250

50

900

250

500

5

Range

Detected

45–100

ND–170

433–691

47–95

229–383

0.11–0.68

Average

67

28

549

73

296

0.25

Range

Detected

32-83

ND

336–577

49–85

181–312

n/a

Average

58

n/a

466

62

248

n/a

Major Source in Drinking Water

Runoff/leaching from natural deposits; seawater influence

Leaching from natural deposits

Substances that form ions when in water; seawater influence

Naturally-occurring organic materials Runoff/leaching from natural deposits

Soil runoff

Alkalinity (mg/L)

Ammonia (mg/L)

Bromide (mg/L)

Calcium (mg/L)

Hardness (mg/L) Magnesium (mg/L) pH

Potassium (mg/L) Sodium (mg/L)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Highest Amt.

Allowed

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Range

Detected

63–115

0.6

ND–0.3

16–31

83–149

11–18

7.6–8.5

1.9–3.2

47–78

Average

84

n/a

0.1

22

112

14

8.0

2.5

63

Range

Detected

51–90

0.5

ND–0.2

12–25

64–120

8.2–14

7.8–8.7

1.8–3.3

39–74

Average

65

n/a

0.1

17

89

11

8.2

2.5

55

PUBLIC MEETINGS

Fourth Wednesday 6:30 p.m.

87 Carol Lane Oakley, CA 94561

925-625-3798 diablowater.org

UCMR4 ASSESSMENT MONITORING 2018–2020

If you have any

Manganese (µg/L)

HAA5 (µg/L)

HAA Br (µg/L)

HAA9 (µg/L)

Total Organic Carbon (TOC) (µg/L)

Bromide (µg/L)

State or

Federal Goal

n/a

n/a

n/a

n/a

n/a

n/a

Notification

Level

500

n/a

n/a

n/a

n/a

n/a

Range

Detected

2.7–62

2.5–9.5

3.1–14

3.6–18

2,000–

4,400

88–261

Average

19

5.1

6.1

8.6

3,275

185

Range

Detected

0.9–45

n/a

n/a

n/a

2,000–

4,300

88–275

Average

12

n/a

n/a

n/a

3,000

191

questions about Diablo Water District tap water, please call 925-625-2112.

UNTREATED WATER TEST RESULTS

Average

2.0

Range

Detected

n/a

Average

n/a

2020 ANNUAL WATER QUALITY REPORT 11

This report contains important information about your drinking water. Have someone translate it for you, or speak with someone who understands it.

Su informe anual de la calidad del agua en español está disponible en línea

en ccwater.com/awqr_es. Este informe contiene información importante sobre su agua potable.

Mahalaga ang impormasyong ito. Mangyaring ipasalin ito.

WANT MORE INFORMATION?

Contra Costa Water District’s website contains valuable information about water issues. Visit ccwater.com to begin your research.