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7A City ofRedwood Ciry Page 6 2007 Public Health Goal Report taps cannot exceed an Action Levet of 15 ppb, as prescribed in Chapter 17.5 of Title 22, California Health and Safety Code. During the 2004 and 2006 Lead and Copper Sampling Redvc�ood City's 90"'percentile values for Iead were below the 15 ppb ma.ximum. Why Lead is Regulated In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine safe levels of ehemicals in drinking water which do, or may cause, health problems. These are non- enforceable Ievels based solely on possible health risks and exposure. The I'HG for lead has been set at 2 parts per billinn(ppb)because the�PA believes that this ievel of protection would not cause any of the potential health probiems described below. Since lead contamination generally occurs from corrosion of household lead pipes, it cannot he directly detected or removed by the water system. Instead, EPA is requiring water systems to control the corrosiveness oF their water if the level of lead at home taps exceeds an MCL. The MCL ior lead has been set at 15 ppb because �i'A believes, gzvei� present technology and resources, this is the lowest level ta which water systems can reasot�abty be required to cont�•al this contaminant should it occur in drinking water at their custo�ners home taps. � These drinking water standards and the regulatians for ensuring these standards are met are called National Primary Drinking Water ReguIations. All gublic water supplies must abide by these regulations. The Health Effects of Lead Lead can cause a variety of adverse heaIth effects when people are exposed to it at levels above the MCL for relatively short periods of time. These effects may incIude interference with red blood cell ehemistry, delays in normal physicaI and mental deveiopment in babies and young ehildren, slight deficits in the attention span,hearing, and learning abilities of children, and slight increases in the blood pressure of some adults, Lon�-term effects: From a iifetime of exposure at levels above the MCL, lead has the potential to cause; stroke; kidney disease; and cancer. Best Availabte TechnoIogy for Lead Eiimination and How It Ts Applied by the City of Redwood City Optimizing corrosion control is considered to be the best treat�nent technique for minimizing household corrosion and reducing lead and copper levels at-the-tap at this time. Currently the San Francisco Public Utilities Coininission (SFPUGthe agency that provides alI of Redwood City's drinking water) uses sodium hydroxide (NaOH} as the treatment technique for adjusting the pH of the tap water for nptimized corrosion control. The City of Redwood Ciry then rrzonitors the pH ievels of the water at the entry points and at sites strategically located throughout the City's water distribution system to ensure that the proper pi�is maintained. A recent report completed by the SFPUC reviewing its Corrosion Control Strategy for Lead and Copper Rule Compiiance confirmed that pH adjustment remains the best strategy for optirnizing corrosion control. The optimal treatment technique, approved by CDHS, is to raise the water to a minimum pH of 8.2; which the SPPUC and the City of Redwood City regularly monitors at entry points and throughout the distribution system. This SFPUC report on Corrosion Control Stxategy has been reviewed and approved by the California Department of Health Services. 4