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2 0 1 7 W A T E R Q U A L I T Y R E P O R T 7 DEFINITIONS 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. 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. SUSCEPTIBILITY OF SOURCES TO POTENTIAL CONTAMINANT SOURCES (PCSS) SOURCE NAME SUSCEPTIBILITY RATING SWAP REPORT DATE Jordan Lake Higher August 2017 The complete SWAP Assessment Report for the Town of Cary (PWS ID# 03-92-020) may be viewed on the Web at: https://www.ncwater.org/?page=600. Please note that because SWAP results and reports are periodically updated by the PWS Section, the results available on this web site may differ from the results that were available at the time this CCR was prepared. To obtain a printed copy of this report, please mail a written request to: Source Water Assessment Program – Report Request, 1634 Mail Service Center, Raleigh NC 27699-1634, or by email request to swap@ncdenr.gov. Please indicate your system name, PWS ID, and provide your name, mailing address and phone number. If you have any questions about the SWAP report please contact the Source Water Assessment Program staff by phone at (919) 707-9098. It is important to understand that a susceptibility rating of "higher" does not imply poor water quality, only the systems' potential to become contaminated by PCS's in the assessment area. SOURCE WATER ASSESSMENT PROGRAM (SWAP) RESULTS The North Carolina Department of Environment and Natural Resources (DENR), Public Water Supply (PWS) Section, Source Water Assessment Program (SWAP) conducted assessments for all drinking water sources across North Carolina. The purpose of the assessments was to determine the susceptibility of each drinking water source (well or surface water intake) to Potential Contaminant Sources (PCSs). The results of the assessment are available in SWAP Assessment Reports that include maps, background information and a relative susceptibility rating of Higher, Moderate or Lower. The relative susceptibility rating of the water source for the Town of Cary was determined by combining the contaminant rating (number and location of PCSs within the assessment area) and the inherent vulnerability rating (i.e., characteristics or existing conditions of the well or watershed and its delineated assessment area).

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