Spatial distribution of coliform bacteria in Batang Arau River, Padang, West Sumatera, Indonesia

The objective of this study was to assess spatial distribution of bacterial population in Batang Arau River. The river water was sampled biweekly, during 3 successive months, and analyzed for coliform bacteria (total coliforms, TC, and fecal coliforms, FC). The results showed that the number of TC range 2.61 – 4.89 log10 number/100 mL and FC 2.48 – 4.79 log10 number/100 mL. The concentration of all parameters inspected has increased from upstream to downstream of the river, except for pH and DO. Bacterial coliforms were strongly correlated with some physicochemical parameters (TSS, TDS, EC and pH), with a Spearman correlation coefficient (r) ranged from -0.599 to 0.827. Analysis of the spatial distribution of the one-way ANOVA at 95% confidence level showed that there were significant differences (p<0.05) in the concentration of bacterial coliforms between upstream and downstream sampling stations as a result of differences in land use and human activity. Cluster analysis grouped 8 sampling stations into two clusters, moderate and high polluted, based on similarities of bacterial characteristics. The bacterial data clearly shows that human health is at a very high risk, as WHO guidelines classification for FC or E. coli in water supplies (WHO 1997) or for agriculture use (WHO 2006) and those strategies for improving water quality of Batang Arau River must be expeditiously implemented.