Indicator bacteria concentrations as affected by hydrologic variables in the Apalachicola river, Florida

A study was carried out at various stages along the Apalachicola river, Fla., to monitor concentrations of faecal coliform and faecal streptococci bacteria. Although there were relatively high discharges of the bacteria along the river, there was a general decreasing trend in coliform numbers in a downstream direction. Coliform densities depended not only on discharge but also on whether the river was rising or falling, whether the flood was at early or a late phase, and the volume of the current peaks relative to earlier peaks. A regression model indicated that 53 per cent of faecal coliform variability could be accounted for by river discharge and 32 per cent could be accounted for by other hydrological characteristics of the flood.