SOURCE OF DRINKING WATER
The source of drinking water used by Glencoe is surface water from Lake Michigan. The sources for 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 can 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 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 may be naturally occurring or result from urban storm water runoff, industrial or domestic waste water discharges, oil and gas production, mining, or farming.
- Pesticides and herbicides, which may come from a variety of sources such as agriculture, urban storm water 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 storm water runoff and septic systems.
- Radioactive contaminants, which may 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 EPA prescribes regulations which limit the amount of certain contaminants in water produced and provided by public water systems. FDA regulations 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. 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/CDC guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the USEPA’s Safe Drinking Water Hotline (1‐800‐426‐4791).
SOURCE WATER INFORMATION
| Source Water: INTAKE (00106) |
Name: Lake Michigan |
Type of Water: Surface Water |
SOURCE WATER ASSESSMENT
To view a summary version of the completed Source Water Assessments, including: Importance of Source Water; Susceptibility to Contamination Determination; and documentation/recommendation of Source Water Protection Efforts, go to the Illinois EPA website at http://dataservices.epa.illinois.gov/swap/factsheet.aspx.
Susceptibility is defined as the likelihood for the source water(s) of a public water system to be contaminated at concentrations that would pose a concern. The Illinois EPA considers all surface water sources of community water supplies to be susceptible to potential pollution problems. The very nature of surface water allows contaminants to migrate into the intakes of water treatment plants with no protection only dilution, which is the reason for mandatory treatment for all surface water supplies in Illinois. Glencoe’s intake is located far enough offshore that shoreline point sources are not considered a factor on water quality. However, at certain times of the year the potential for contamination exists due to storm water runoff and wet‐weather flows from the North Shore Channel. If currents are flowing in a northerly direction, contaminants from these flows could migrate to Glencoe’s intake and compromise water quality. A correlation between Northbrook’s rainfall data and North Shore Channel's discharge dates show the potential effect of these flows on Glencoe’s water quality. The proximity to a major shipping lane adds to the susceptibility should there be a spill near the intake.
2021 REGULATED CONTAMINENTS DETECTED
LEAD AND COPPER
Definitions:
- Action Level: The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow.
- Action Level Goal (ALG): The level of a contaminant in drinking water below which there is no known or expected risk to health. ALGs allow for a margin of safety.
|
Lead and Copper |
Date Sampled |
MCLG |
Action Level (AL) |
90th Percentile |
# Sites Over AL |
Units |
Violation |
Likely Source of Contamination |
|
Copper |
2021 |
1.3 |
1.3 |
0.22 |
0 |
ppm |
No |
Erosion of natural deposits; Leaching from wood preservatives; Corrosion of household plumbing systems. |
|
Lead |
2021 |
0 |
15 |
6.5 |
1 |
ppb |
No |
Corrosion of household plumbing systems; Erosion of natural deposits. |
ppb: micrograms per liter or parts per billion ‐ or one ounce in 7,350,000 gallons of water.
ppm: milligrams per liter or parts per million ‐ or one ounce in 7,350 gallons of water.
Definitions: The following tables contain scientific terms and measures, some of which may require explanation.
- Avg: Regulatory compliance with some MCL’s are based on running annual average of monthly
- Level 1 Assessment: A Level 1 assessment is a study of the water system to identify potential problems and determine (if possible) why total coliform bacteria have been found in our water system.
- Level 2 Assessment: A Level 2 assessment is a very detailed study of the water system to identify potential problems and determine (if possible) why an coli MCL violation has occurred and/or why total coliform bacteria have been found in our water system on multiple occasions.
- Maximum Contaminant Level Goal or MCLG: The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.
- Maximum Contaminant Level or MCL: The highest level of a contaminant that is allowed in drinking MCLs are set as close to the MCLGs as feasible using the best available treatment technology.
- Maximum residual disinfectant level goal or MRDLG: The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLG’s do not reflect the benefits of the use of disinfectants to control microbial contaminants.
- Maximum residual disinfectant level or MRDL: The highest level of a disinfectant allowed in drinking There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.
- na: not applicable
- pCi/L: picocuries per liter (a measure of radioactivity)
- ppb: micrograms per liter or parts per billion – or one ounce in 7,350,000 gallons of
- ppm: milligram per liter or parts per million – or one ounce in 7,350 gallons of
- Treatment Technique or TT: A required process intended to reduce the level of a contaminant in drinking
- NTU: Nephelometric Turbidity Units ‐ a measure of water
- Turbidity: Is a measurement of the cloudiness of the water caused by suspended We monitor it because it is a good indicator of water quality and the effectiveness of our filtration system and disinfectants.
REGULATORY CONTAMINANTS
|
Disinfectants and Disinfection By‐Products |
Collection Date |
Highest Level Detected |
Range of Levels Detected |
MCLG |
MCL |
Units |
Violation |
Likely Source of Contamination |
|
Chlorine |
2021 |
1.0 |
0.7 – 1.0 |
MRDLG = 4 |
MRDL = 4 |
ppm |
No |
Water additive used to control microbes. |
|
Haloacetic Acids (HAA5) |
2021 |
12.75 |
9.23 – 12.75 |
No goal for the total |
60 |
ppb |
No |
By‐product of drinking water chlorination. |
|
Total Trihalomethanes (TTHM) |
2021 |
33.0 |
30.6 – 33.0 |
No goal for the total |
80 |
ppb |
No |
By‐product of drinking water chlorination. |
Avg: Regulatory compliance with some MCL’s are based on running annual average of monthly samples.
ppb: micrograms per liter or parts per billion – or one ounce in 7,350,000 gallons of water.
ppm: milligram per liter or parts per million – or one ounce in 7,350 gallons of water.
|
Inorganic Contaminants |
Collection Date |
Highest Level Detected |
Range of Levels Detected |
MCLG |
MCL |
Units |
Violation |
Likely Source of Contamination |
|
Barium |
2021 |
0.019 |
0.019 – 0.019 |
2 |
2 |
ppm |
No |
Discharge of drilling wastes; Discharge from metal refineries; Erosion of natural deposits. |
|
Fluoride |
2021 |
0.729 |
0.729 – 0.729 |
4 |
4 |
ppm |
No |
Erosion of natural deposits; Water additive which promotes strong teeth; Discharge from fertilizer and aluminum factories. |
|
Nitrate (measured as Nitrogen) |
2021 |
0.38 |
0.38 – 0.38 |
10 |
10 |
ppm |
No |
Runoff from fertilizer use; Leaching from septic tanks, sewage; Erosion of natural deposits. |
|
Sodium |
2021 |
11 |
11 – 11 |
na |
na |
ppm |
No |
Erosion from naturally occurring deposits: Used in water softener regeneration. |
Avg: Regulatory compliance with some MCL’s are based on running annual average of monthly samples.
na: not applicable
ppm: milligram per liter or parts per million – or one ounce in 7,350 gallons of water.
Definitions:
- Turbidity: Is a measurement of the cloudiness of the water caused by suspended We monitor it because it is a good indicator of water quality and the effectiveness of our filtration system and disinfectants.
- Treatment Technique or TT: A required process intended to reduce the level of a contaminant in drinking
|
|
Limit (Treatment Technique) |
Level Detected |
Violation |
Likely Source of Contamination |
|
Lowest monthly % meeting limit |
TT = 0.3 NTU |
100% |
No |
Soil runoff. |
|
Highest single |
TT = 1 NTU MAX |
0.094 NTU |
No |
Soil runoff. |
NTU: Nephelometric Turbidity Units ‐ a measure of water clarity.
TOTAL ORGANIC CARBON
The percentage of Total Organic Carbon (TOC) removal was measured each month and the system met all TOC removal requirements set, unless a TOC violation is noted in the violations section.
VIOLATIONS SUMMARY TABLE
We are happy to report that no monitoring, reporting, treatment technique, maximum disinfectant residual level, or maximum contaminant level violations were recorded during 2021.
2021 UNREGULATED CONTAMINANTS
In 2021 Glencoe’s Public Water Supply (PWS) was sampled as part of the State of Illinois PFAS Statewide Investigation. Results from this sampling indicated PFAS were detected in our drinking water above the health advisory level established by the Illinois EPA. Follow up monitoring is being conducted. For more information about PFAS health advisories https://www2.illinois.gov/epa/topics/water‐ quality/pfas/Pages/pfas‐healthadvisory.aspx
A maximum contaminant level (MCL) for these contaminants has not been established by either state or federal regulations, nor has mandatory health effects language been set. The purpose of unregulated contaminant monitoring is to assist USEPA in determining the occurrence of unregulated contaminants in drinking water and whether future regulation is warranted.
UNREGULATED CONTAMINANTS
|
PFAS Analyte |
Collection Date |
Highest Level Detected |
Range of Levels Detected |
Health‐Based Guidance Level |
Units |
Typical Source |
|
Perfluorooctanesulfonic acid (PFOS) |
2021 |
2.5 |
ND ‐ 2.5 |
14 |
ppt |
Manufactured chemical(s); used in household goods for stain, grease, heat and water resistance. |
|
Perfluorooctanoic acid (PFOA) |
2021 |
2.3 |
ND ‐ 2.3 |
2 |
ppt |
Manufactured chemical(s); used in household goods for stain, grease, heat and water resistance. |
Minimum reporting level (MRL) = 2.0 ppt
ppt: parts per trillion or nanograms per liter – or one ounce in 7,350,000,000 gallons of water.
ND: not detected
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