Historical fecal indicator bacteria measurements （n = 125,000; 10 years） in Orange County coastal zone, an interface with urban watershed that is one of the most developed areas in the United States and source of hi...Historical fecal indicator bacteria measurements （n = 125,000; 10 years） in Orange County coastal zone, an interface with urban watershed that is one of the most developed areas in the United States and source of highly polluted runoff discharges, have been compiled and analyzed. During the period from 2000 to 2010, fecal indicator bacteria concentrations in Orange County Beaches progressively increased （poor water quality） in the first half of the decade and progressively decreased （improved water quality） during the last half of the decade. Among all physical, chemical and environmental factors, 59%-74% of the variability in the fecal indicator bacteria concentrations in the coastal zone records can be attributed to seasonal and interannual variability in local rainfall, implying that stormwater runoff from the surrounding urban watershed is a primary source of fecal pollution in Orange County Beaches. These results suggest that efforts to improve water quality in Orange County Beaches and protect beach-goers from pollution will likely have greater efficacy during wet weather periods than the rest of the year. In addition, this study identified the effect of alongshore surf zone current on fecal pollution caused by coastal waves. The data and analysis presented in this paper provide a framework for evaluating the longer period water quality trend in the coastal area, and elucidate Best-Management-Practices that can improve public health protection by managing coastal water quality compliance with standards.展开更多
文摘Historical fecal indicator bacteria measurements （n = 125,000; 10 years） in Orange County coastal zone, an interface with urban watershed that is one of the most developed areas in the United States and source of highly polluted runoff discharges, have been compiled and analyzed. During the period from 2000 to 2010, fecal indicator bacteria concentrations in Orange County Beaches progressively increased （poor water quality） in the first half of the decade and progressively decreased （improved water quality） during the last half of the decade. Among all physical, chemical and environmental factors, 59%-74% of the variability in the fecal indicator bacteria concentrations in the coastal zone records can be attributed to seasonal and interannual variability in local rainfall, implying that stormwater runoff from the surrounding urban watershed is a primary source of fecal pollution in Orange County Beaches. These results suggest that efforts to improve water quality in Orange County Beaches and protect beach-goers from pollution will likely have greater efficacy during wet weather periods than the rest of the year. In addition, this study identified the effect of alongshore surf zone current on fecal pollution caused by coastal waves. The data and analysis presented in this paper provide a framework for evaluating the longer period water quality trend in the coastal area, and elucidate Best-Management-Practices that can improve public health protection by managing coastal water quality compliance with standards.
