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contaminants are below MCLs. Monitoring schedules and results can be viewed for both agencies at the Drinking Water Watch website https://sdwis.waterboards.ca.qov/PDWW/) and by entering "Zone 7" or the "City of Pleasanton" under the Water System Name. In general, the City: monitors fluoride and chlorine at entry points into the distribution system on a daily basis; monitors for chlorine and total coliform at approximately 30 rotating sample locations within the distribution system on a weekly basis; monitors for disinfectant byproducts in the distribution system on a quarterly basis; and monitors for the majority of all other contaminants in the groundwater supply on 3+ year frequencies. Zone 7 has similar monitoring requirements, but their surface water supply monitoring is more extensive, including 1- year frequencies. The City is required to annually prepare a consumer confidence report (CCR) that is provided to each customer. The purpose is to report any level of regulated contaminants detected in the drinking water, the level of the contaminant vs. the PHG and MCL, and if any violations occurred. A copy of the City's 2018 CCR is included in Attachment 5. All water quality testing met applicable standards without any violations. The City is also required to prepare a report every three years on the detection of any regulated contaminants above the PHG and hold a public hearing regarding the report. The latest report was prepared on June 30, 2019 and recommends no additional actions. A public hearing will occur in the coming months. Unregulated Contaminants The DDW will establish health-based advisory levels for certain non-regulated chemicals in drinking water that lack MCLs. These advisory levels are established due to actual contamination events or in anticipation of possible contamination. To date, of the 95 chemicals for which advisory levels have been established, 40 now have MCLs, 31 remain current with advisory levels, and 24 are archived. The advisory levels for each chemical contain both Notification Levels and Response Levels. Notification Levels are non-regulatory, precautionary health-based advisory levels of contaminants in drinking water that pose no significant health risk if consumed for a lifetime based on the most sensitive known health endpoints for the compounds. Response Levels are concentrations of contaminants in drinking water where the margin of safety in health risk included at the Notification Level has been reduced to the point where action is recommended. Attachment 6 includes a list of the 31 current chemicals and there corresponding Notification Levels. Public water systems are not required to monitor for non-regulated contaminants, with the exception of occasional mandated special testing programs such as UCMR (unregulated chemicals requiring monitoring) where DDW collects data over a set duration. However, if during voluntary testing or during UCMR testing, a public water system exceeds the advisory levels for a contaminant then the following applies (note both City and Zone 7 water testing is applicable to City notifications): 1. Contaminant Exceeds the Notification Level • Required by Statue to notify the governing body of the City. • Recommended by DDW to notify consumers via CCR or other methods such as website postings. Page 5 of 13