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(Data in this report is furnished by CCMWA)
How to Read this Report
The table shows the results of the Cobb County-Marietta Water Authority’s water quality analysis. The table contains the name of each substance, the highest level allowed by regulation (MCL), the ideal goals for public health (MCLG), the usual sources of such contamination, footnotes explaining our finding, and key to units of measurement. Every regulated contaminant that we detected in the water, even in the most minute traces, is listed here.
The Georgia Environmental Protection Division has determined that the concentration of certain water quality monitoring parameters does not change frequently within our system, therefore some of the data presented in this report are greater than one year old.
Health Related Concerns
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. EPA/CDC guidelines on appropriate means to lessen the risk of infection by Cryptosporidium are available from the EPA’s Safe Drinking Water Hotline at 1 (800) 426-4791.
Water quality data for community water systems throughout the United Sates are available on the internet at www.waterdata.com.
Definitions
AL (Action Level): The concentration of a contaminant which, if exceeded, triggers treatment or other requirements that a water system must implement.
BDL: Below Detection Limits
MCL (Maximum Contaminant Level): The highest level of a contaminant that is allowed in drinking water. MCL’s are set as close to the MCLG’s as feasible using the best available treatment technology.
MCLG (Maximum Contaminant Level Goal): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLG’s allow for a margin of safety.
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 microbiological 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. MRDLG’s do not reflect the benefits of the use of disinfectants to control microbial contaminants.
n/a: not applicable.
n/d: not detectable.
NTU (Nephelometric Turbidity Unit): measures the cloudiness of water.
ppm: parts per million (or milligrams per liter which corresponds to one penny in $10,000).
ppb: parts per billion (or micrograms per liter which corresponds to one penny in $10,000,000).
range: the highest to the lowest level detected.
TT (Treatment Technique): A required process intended to reduce the level of a contaminant in drinking water.
What are Cryptosporidium and Giardia?
The Cobb County – Marietta Water Authority participated in a major drinking water quality testing program called the Supplemental Information Collection Rule (SICR). Two of the contaminants tested for under this rule are the parasites Cryptosporidium and Giardia, which have caused outbreaks of intestinal disease in the United States and abroad. These parasites are common in surface water, very difficult to kill and even a well-run water system may contain some live oocysts (in the case of Cryptosporidium) or cysts (in the case of Giardia). The U.S. Environmental Protection Agency is working to resolve several scientific issues that will allow it to set Cryptosporidium and Giardia safety standards.
The testing, performed at the raw (untreated) water intake on the Chattahoochee River, located immediately north of the Johnson Ferry Road crossing, revealed the presence of Cryptosporidium and/or Giardia in several months’ samples. These organisms were detected in the water prior to treatment.
Following is a table detailing these occurrences. The treatment technique is designed and optimized to remove these contaminants, therefore no precaution about our drinking water is currently needed for the general public. See advice about special populations and a source for further information in the preceding Why are there contaminants section of this report.
Cryptosporidium Occurrences
| Cryptosporidium Occurrences | |
| Date | # of Oocysts/10 L |
| June 16, 1999 | 1 |
| June 29, 1999 | 1 |
| September 28, 1999 | 1 |
| November 8, 1999 | 2 |
| Giardia Occurrences | |
| September 28, 1999 | 19 |
| October 12, 1999 | 9 |
| October 25,. 1999 | 10 |
| November 8, 1999 | 10 |
| November 22, 1999 | 6 |
Giardia Occurrences
During the same monitoring periods as the Chattahoochee River, the water at Lake Allatoona was tested. No oocysts or cysts were detected.
In order to comply with an upcoming federal regulation, the Cobb County–Marietta Water Authority has been monitoring for Cryptosporidium and Giardia in the raw water from both its water sources. The monitoring was performed on both Lake Allatoona and the Chattahoochee River water sources monthly during 2005. No Cryptosporidium oocysts were detected at either source. Giardia cysts were detected in two of the twelve samplings. Again, these organisms were detected in the water prior to treatment. All of the occurrences were at the Chattahoochee River intake:
| Giardia Occurrences | |
| Date | # of Cysts/10 L |
| January 14, 2005 | 2 |
| February 14, 2005 | 1 |