2008 Water Quality Table for Westlake

Primary Drinking Water Standards

MWD

Calleguas Lake Bard

Distribution System-Wide

Radiological

Year Tested

Unit

MCL

PHG (MCLG)

Exceeded Standard?

Range

Average

Range

Average

Range

Average

Source of Substance

Gross alpha particle activity

2008

pCi/L

(0)

ND–7.3

3.4

n/a

Erosion of natural deposits

Uranium

2005–2008

pCi/L

0.43

1.6–2.0

1.8

ND–1.9

n/a

Erosion of natural deposits

Inorganic Chemicals

Year Tested

Unit

MCL (SMCL)

PHG

Exceeded Standard?

Range

Average

Range

Average

Range

Average

Source of Substance

Aluminum

2008

ppm

1 (0.2)

0.6

0.06–0.1

0.9

n/a

Erosion of natural deposits; residue from some surface water treatment processes

Arsenic

2008

ppb

0.00

2.0–2.8

2.3

n/a

Erosion of natural deposits; runoff from orchards; glass and electronics production wastes

Fluoride (treatment by MWD)1

2008

ppm

0.6–0.9

n/a

0.7–0.9

0.8

0.2–1.0

0.7

Water additive for dental health

Nitrate (as nitrogen)

2008

ppm

0.6–0.9

0.7

n/a

Runoff and leaching from fertilizer use; leaching from septic tanks and sewage; erosion of natural deposits

Year Tested

Unit

MCL

PHG (MCLG)

Exceeded Standard?

Highest Level

Lowest Monthly Percent

Highest Level

Lowest Monthly Percent

Highest Level

Lowest Monthly Percent

Source of Substance

Turbidity (surface water requiring filtration)2

2008

NTU

n/a

0.06

100%

0.09

100%

n/a

Soil runoff

Disinfection Byproducts

Year Tested

Unit

MCL

PHG (MCLG)

Exceeded Standard?

Range

Highest Annual Average

Range

Highest Annual Average

Range

Highest Annual Average

Source of Substance

Bromate3

2008

ppb

(0)

4–10

n/a

Byproduct of drinking water disinfection

Total haloacetic acids

2008

ppb

n/a

5.0–7.8

12.4

Byproduct of drinking water chlorination

Total trihalomethanes

2008

ppb

n/a

17.2–50.2

30.7

Byproduct of drinking water chlorination

Disinfectant and DBP Precursor

Year Tested

Unit

MRDL

MRDLG

Exceeded Standard?

Range

Average

Range

Average

Range

Average

Source of Substance

Chloramine

2008

ppm

n/a

0.4–3.5

2.1

Drinking water disinfectant added for treatment

Total organic carbon4

2008

ppm

n/a

2.0–2.4

2.6

2.2–2.4

2.4

n/a

Naturally present in the environment

Other Regulated Substances

Metals

Year Tested

Unit

PHG

Exceeded Standard?

90th Percentile

Samples > AL

90th Percentile

Samples > AL

90th Percentile

Samples > AL

Source of Substance

Copper

2007

ppm

1.3

0.3

n/a

0.1

0 of 30

Internal corrosion of household plumbing systems; discharge from industrial manufacturers; erosion of natural deposits

Secondary Drinking Water Standards and Unregulated Compounds

Inorganic Chemicals

Year Tested

Unit

SMCL

PHG (MCLG)

Exceeded Standard?

Range

Average

Range

Average

Range

Average

Source of Substance

Boron

2006–2008

ppm

NL=1

n/a

0.1–0.2

0.2

0.20

n/a

Erosion of natural deposits

Calcium

2006–2008

ppm

n/a

23–32

28–31

n/a

Erosion of natural deposits

Chloride

2006–2008

ppm

500

n/a

72–80

n/a

Erosion of natural deposits; seawater influence

Chromium 6+

2006–2008

ppb

n/a

0.3–0.5

0.1

n/a

Discharge from steel and pulp mills and chrome plating; erosion of natural deposits

Color

2006–2008

Units

n/a

1–2

ND–12

n/a

Naturally occurring organic matter

Hardness

2006–2008

ppm

n/a

108–130

121

127–139

133

n/a

Municipal and industrial waste discharges

Magnesium

2006–2008

ppm

n/a

11–13

14–15

n/a

Erosion of natural deposits

Odor

2006–2008

Units

n/a

Erosion of natural deposits

2006–2008

Units

n/a

8.2–8.4

8.3

8.2–8.4

8.3

n/a

Leaching from natural deposits

Sodium

2006–2008

ppm

n/a

56–68

64–65

n/a

Naturally occurring organic matter

Specific conductance

2006–2008

µS/cm

1600

n/a

516–591

552

581–596

588

n/a

Inherent characteristic of water

Sulfate

2006–2008

ppm

500

n/a

47–71

70–71

n/a

Erosion of natural deposits

Total dissolved solids

2006–2008

ppm

1000

n/a

283–333

307

260–330

298

n/a

Erosion of natural deposits; seawater influence

Vanadium

2006–2008

ppb

NL=50

n/a

4.6–5.1

4.9

n/a

Runoff/leaching from natural deposits; industrial wastes

Disinfection Byproducts

Year Tested

Unit

MCL (SMCL)

PHG (MCLG)

Exceeded Standard?

Range

Highest Annual Average

Range

Highest Annual Average

Range

Highest Annual Average

Source of Substance

Chlorate

2008

ppb

n/a

Byproduct of drinking water chlorination; industrial processes

n-Nitrosodimethylamine

2008

ppt

NL=10

2.4–7.4

n/a

Byproduct of drinking water chlorination; industrial processes

1In November 2007, Metropolitan Water District of Southern California (MWD) began fluoridating its treated surface water, which Cal Water imports through Calleguas Municipal Water District (CMWD). The range of fluoride concentrations indicated in the "Purchased Surface Water" column are the fluoride levels in samples collected from MWD's water. Samples are collected throughout the distribution system every month to verify the actual levels at various locations. Concentrations indicated in the "Distribution System-Wide" column are the monitoring results of these samples. The optimal fluoride level for the Westlake system is 0.8 ppm with a control range of 0.7–1.3 ppm.

2For surface water systems, the Treatment Technique (TT) dictates that the turbidity level of the filtered water shall be less than or equal to 0.3 NTU in 95% of the measurements taken each month and shall not exceed 1 NTU at any time. Turbidity is a measure of the cloudiness of the water and is an indicator of treatment performance. Turbidity is monitored because it is a good indicator of the effectiveness of the filtration system.

3Some people who drink water containing bromate in excess of the MCL over many years may have an increased risk of getting cancer.

4Total organic carbon (TOC) has no health effects; however, TOC provides a medium for the formation of disinfection byproducts. These byproducts include THMs and HAAs. Drinking water containing these byproducts in excess of the MCL may lead to adverse health effects, liver or kidney problems, or nervous system effects, and may lead to an increased risk of cancer. Concerns regarding disinfection byproducts are based upon exposure over many years.

How to Read This Table

We test your water for more than 100 regulated contaminants. The table in this report lists only those that were detected.

The table shows water quality test results divided into two main sections: “primary standards” and “secondary standards.” Primary standards protect public health by limiting the levels of contaminants in drinking water. Secondary standards are limits for substances that could affect the water's taste, odor, or appearance.

Definitions

µS/cm = measure of specific conductance
n/a = not applicable
ND = not detected
NTU = nephelometric turbidity unit
pCi/L = picoCuries per liter (measure of radioactivity)
ppb = parts per billion (micrograms per liter)
ppm = parts per million (milligrams per liter)
SMCL = secondary maximum contaminant level

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.

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 (USEPA).

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 are economically and technologically feasible. Secondary MCLs are set to protect the odor, taste, and appearance of drinking water.

Maximum Residual Disinfectant Level Goal (MRDLG): The level of a disinfectant added for water treatment below which there is no known or expected risk to health. MRDLGs are set by the USEPA.

Maximum Residual Disinfectant Level (MRDL): The level of a disinfectant added for water treatment that may not be exceeded at the consumer's tap.

Notification Level (NL): A health-based advisory level for an unregulated contaminant in drinking water. It is used by the California Department of Public Health to provide guidance to drinking water systems.

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

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

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

Potential Sources of Contamination

All 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 U.S. Environmental Protection Agency (USEPA) Safe Drinking Water Hotline at (800) 426-4791.

The sources of drinking water (both tap and bottled) 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 human activity. Contaminants that may be present in source water include:

Microbial contaminants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.

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

Pesticides and herbicides, which 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 can also come from gas stations, urban stormwater runoff, and septic systems.

Radioactive contaminants, which can be naturally occurring or 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 (USEPA) and the California Department of Public Health (Department) prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. Department regulations also establish limits for contaminants in bottled water, which must provide the same protection for public health.

Some people may be more vulnerable to contaminants in drinking water than the general population. Immunocompromised people, such as those with cancer undergoing chemotherapy, those who have undergone organ transplants, those with HIV/AIDS or other immune system disorders, some elderly people, and infants, can be particularly at risk from infections. These people should seek advice from their health care providers about drinking water. USEPA/Centers for Disease Control and Prevention (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 (800) 426-4791.

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