2015 Water Quality Report

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1 Compliance with the MRDLs for Disinfectants and MCLs for Disinfection By-Products is based on the running annual average (RAA) or locational running annual average (LRAA) shown in the "Amount Detected" column. The RAA or LRAA reported is the highest for the year. 2 Based on the average Total Organic Carbon (TOC) and alkalinity levels in our source water, we are required to meet an average % removal for TOC of 45%, which equates to a removal ratio of 1.0 and is classified by the State as the Step 1 compliance method. If we do not achieve that % removal, there is an alternative % removal requirement. If we also fail to meet that, we are in violation of a Treatment Technique. In 2015, our average % removal for TOC was 67%, or a removal ratio of 1.51. We utilized the Step 1 compliance method and were in compliance with regulatory requirements for TOC removal throughout the year. 3 Turbidity is a measure of the cloudiness of the water. We monitor it because it is a good indicator of the effectiveness of our filtration system. The turbidity rule requires that 95% or more of the monthly samples must be less than or equal to 0.3 NTU. 4 Unregulated contaminants are those for which the U.S. EPA has not established drinking water standards. The purpose of unregulated contaminant monitoring is to assist the EPA in determining the occurrence of unregulated contaminants in drinking water and whether future regulations are warranted. Definitions AL (Action Level): The concentration of a contaminant that, if exceeded, triggers treatment or other requirements that a water system must follow. LRAA (Locational Running Annual Average): 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 By-Products Rule. MCL (Maximum Contaminant Level): 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. MCLG (Maximum Contaminant Level Goal): 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. 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 microbial 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. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants. NA: Not applicable ND (Not detected): Indicates that the substance was not found by laboratory analysis. NTU (Nephelometric Turbidity Units): Measurement of the clarity, or turbidity, of water. Turbidity in excess of 5 NTU is just noticeable to the average person. ppb (parts per billion): One part substance per billion parts water (or micrograms per liter). ppm (parts per million): One part substance per million parts water (or milligrams per liter). removal ratio: A ratio between the percentage of a substance actually removed to the percentage of the substance required to be removed. SMCL (Secondary Maximum Contaminant Level): SMCLs are established to regulate the aesthetics of drinking water like taste and odor. TT (Treatment Technique): A required process intended to reduce the level of a contaminant in drinking water.

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