According to Heal The Bay, San Mateo County beaches have the poorest water quality during the summer in California. Heal The Bay is an environmental nonprofit group that tested bacteria levels of more than 500 beaches along the California coastline.
10 most polluted beaches in the state — includes six bacteria-impaired beaches within San Mateo County. This is an unusually high number of beach bummers for a single county. The remaining four beach bummers are located in Southern California and are frequent pollution offenders
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