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Water Distribution Once the water from Zone 7 passes through the turnouts or is pumped by the City out of the groundwater wells, it is said to have entered the City's distribution system. The City's distribution system consists of 18 pressure zones. Refer to Attachment 1 - Figure 3-1 and 3-2 for illustrations of the City's different pressure zones which are shown by color. With the exception of Turnouts 6 and 7, which feed the Ruby Hill pressure zones directly, all turnouts and City wells feed the City's Lower Zone. The Lower Zone is by far the City's largest pressure zone in terms of surface area and water demand. Once water enters the Lower Zone it is delivered through a piping network to meet customer demands within the pressure zone and stored in tanks for later use during peak demand periods or during fire/emergency events. The water from the Lower Zone is also pumped by several pump stations to the other pressure zones located at higher elevations of the city (i.e. west and southeast ends of the city). In these pressure zones, the water is also delivered to meet customer demands and stored in tanks for later use during peak demand periods or during fire/emergency events. Overall the City's water distribution system consists of 14 pump stations, 20 reservoirs, and 330 miles of piping. Regulated Contaminants The State Water Resource Control Board (SWRCB) Division of Drinking Water (DDW) is responsible for the regulation of contaminants in drinking water. Regulated contaminants in drinking water are called maximum contaminant levels (MCLS), found in Title 22 of the California Code of Regulations, and must be met by public water systems. Primary MCLs address health concerns and include microbiological contaminants, radioactive contaminants, inorganic contaminants, synthetic organic contaminants, volatile organic contaminants, and disinfection byproducts. Attachment 2 contains a list of MCLs for primary contaminants as of October 2018. Secondary MCLs address esthetics such as taste and odor. Attachment 3 contains a list of MCLs for secondary contaminants as of October 2018. MCLs take into account not only a chemical's health risks, but also factors such as their detectability and treatability, as well as costs of treatment. Public Health Goals (PHGs) for contaminants are different than MCLs. PHGs are established by the California Office of Environmental Health Hazard Assessment (OEHHA). They are concentrations of drinking water contaminants that pose no significant health risk if consumed for a lifetime based on current risk assessment principles, practices, and methods. Per Health and Safety Code, OEHHA must establish PHGs for all contaminants that have or will have MCLs adopted. Per Health and Safety Code, DDW must establish a contaminant's MCL at a level as close to its PHG as is technologically and economically feasible with primary emphasis on the protection of public health. MCLs and PHGs are required to be reviewed by the DDW and OEHHA at least once every five years. As part of the review they must confirm that there are no changes in technology/treatment that permit better attainment of the PHG or no new scientific evidence that the contaminant may present a materially different risk to public health then was previously determined. Attachment 4 includes a list of regulated contaminants' MCLs and PHGs. Zone 7's water system facilities (i.e. treatment plants, groundwater wells, and transmission system) and the City's water system facilities (i.e. groundwater wells and distribution system) are placed under monitoring programs by DDW to confirm regulated Page 4 of 13