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7C Page 6 City of Redwood City 2010 Public Health Goal Report contaminant level goals (MCLGs) adopted by the U.S. Environmental Protection Agency (USEPA) must be used if a PHG has not been adopted for a regulated contaminant. PHG/MCLG vs. MCL PHGs are set by the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA) and are based solely on public health risk considerations. MCLs are set by the U.S. Environmental Protection Agency (USEPA) or the California Department of Public Health (CDPH) as the level which is required to be met in water systems. Violations of an MCl can. result in a fine, abatement order, or closure of facilities. When the USEPA or the CDPH adopts an MCl, they take into account such factors as (1) analytical methodologies; (2) effectiveness of available treatment technologies; and (3) benefits and costs. PHGs and MCLGs are not enforceable and are not required to be met by any public water system. Water Quality Data Reviewed for this Report Water quality data collected by the City of Redwood City during 2007, 2008, and 2009 for the purpose of determining compliance with drinking water standards were reviewed in order to prepare this PHG report. This data was all summarized in our 2007, 2008, and 2009 Annual Water Quality Reports (also known as Consumer Confidence Reports (CCRs)) that were distributed to all of our customers though direct mail. Guidelines Followed for Preparation of this Report The Association of California Water Agencies (ACWA) formed a workgroup which prepared guidelines for water utilities to use in preparing these required reports. The ACWA guidelines were used in the preparation of this report. Best Available Treatment Technology and Cost Estimates Both USEPA and CDPH adopt Best Available Technologies (BATs), which are the best known methods of reducing contaminant levels below the MCL. While a BAT may identify a process that can reduce the presence of a contaminant, the cost of implementation can be a major factor in deciding whether or not to adopt the process. For a system that is in compliance with MCL levels, cost considerations must be a factor. Striving to keep contaminants below PHG/MCLG levels must be evaluated with costs in mind. Costs were estimated for the implementation of BATs for each constituent exceeding a PHG or MCLG. The PHGs and MCLGs are set much lower than the MCL, and it is not always possible or feasible to determine what treatment is needed to further reduce a constituent to, or below, the PHG or MCLG. In some cases, such as when the MCLG or PHG is set at zero, there may not be commercially available technology to reach that level. The issue is further complicated because it is often not possible to verify by analytical means that the contaminant has been totally eliminated. In some casesl installing a treatment technology to try and further reduce very low levels of one constituent may, in turn, have adverse effects on other aspects of water quality. This report presents the required cost estimates to implement the BATs to reduce a contaminant to a level at or below the PHG/MCLG. 2