Impact of recreation on recreational water quality of a small tropical stream

A study was conducted to determine the possible influence of recreation on microbiological water quality of a tropical stream. Microbiological water quality was measured at several recreational sites along the stream and a separate experiment was conducted to look at the effect of sediment resuspension on microbiological water quality. Microbiological quality of the water in the stream was generally poor and varied widely with faecal coliform and Escherichia coli levels ranging from 1 to > 16 000 and 14 to 9615 organisms 100 ml(-1) respectively. Levels of faecal coliforms were higher in the wet (median 700 organisms 100 ml(-1)) than the dry (median 500 organisms 100 ml(-1)) season while the reverse was true for E. coli (median 300 and 220 organisms 100 ml(-1) in the wet and dry seasons respectively). Recreational activity resulted in reduced water quality: sites with recreation had poorer water quality than those without; water quality was generally poorer when there were high numbers of recreational users. Wading resulted in a 4-fold increase in mean E. coli densities and a 3-fold increase in total suspended sediments in the overlying water suggesting that the increases were due to suspension of bacteria from the sediments. We conclude that water quality monitoring methodology for assessing recreational water quality should be amended to factor in the effects of wading since environmental strains of bacteria can be pathogenic and thus represent a human health threat.