TOC

C A RY, N O RT H C A R O L I N A A N N U A L WAT E R Q U A L I T Y R E P O R T 2 0 2 2 11 Action Level (AL): The concentration of a contaminant that, if exceeded, triggers treatment or other requirements that a water system must follow. Locational Running Annual Average (LRAA): The average of sample analytical results for samples taken at a particular monitoring location during the previous four calendar quarters under the Stage 2 Disinfectants and Disinfection Byproducts Rule. Hazard Index: A tool EPA is proposing that water systems use to evaluate combined health risks from 4 different PFAS compounds in drinking water. Maximum Contaminant Level (MCL): The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment technology. 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 allow for a margin of safety. Maximum Residual Disinfectant Level (MRDL): 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. 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 contamination. Nephelometric Turbidity Unit (NTU): Nephelometric turbidity unit is a measure of the clarity of water. Turbidity in excess of 5 NTU is just noticeable to the average person. Not-Applicable (N/A): Information not applicable/ not required for that particular water system or for that particular rule. Non-Detects (ND): Laboratory analysis indicates that the contaminant is not present at the level of detection set for the particular methodology used. Parts per billion (ppb) or Micrograms per liter (ug/L): One part per billion corresponds to one minute in 2,000 years or a single penny in $10,000,000. Parts per million (ppm) or Milligrams per liter (mg/L): One part per million corresponds to one minute in two years or a single penny in $10,000. Parts per trillion (ppt) or Nanograms per liter (nanograms/L): One part per trillion corresponds to one minute in 2,000,000 years or a single penny in $10,000,000,000. Picocuries per liter (pCi/L): Picocuries per liter is a measure of the radioactivity in water. Removal Ratio: A ratio between the percentage of a substance actually removed to the percentage of the substance required to be removed. Treatment Technique (TT): A required process intended to reduce the level of a contaminant in drinking water. WAT E R T R E AT M E N T D E F I N I T I O N S Operators work around the clock 24 hours a day, 365 days a year, treating your drinking water.

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