The primary objective of this research was to evaluate the relationship between the predominant human activities in the study region and seasonal bacteriological surface water quality (based on concentrations of bacterial indicators, most specifically, 'Escherichia coli'). Surface waters were monitored at 15 discrete geographical locations throughout the spring and summer seasons of 2002 and 2003. Mean concentrations of ' E. coli' in the control site, relatively unaffected by human activity, ranged from 0 to 3 cfus 'E. coli'/100 ml; this range represents baseline bacteriological quality. Sites affected by multiple human uses, especially the more urbanized sites, had seasonal mean concentrations ranging from 6 to 44 cfus 'E. coli'/100 ml. An anthropogenic usage index was developed that ranked sites according to the magnitude of human activity to the volume of water at a given site (bay). Regression analysis indicated a strong relationship between this index and the bacteriological quality of affected surface waters.