Bottom Sediment: A Reservoir of Escherichia coli in Rangeland Streams

Escherichia coli concentrations of bottom sediment and overlying water were determined from a variety of streams in southwestern Idaho by a one-step most probable number technique. Results show E. coli concentrations of bottom sediments to be from 2 to 760 times greater than from the overlying water. E. coli concentrations of bottom sediment were found to be resuspended following disturbance simulation and a rainstorm event, contributing to pollution of the overlying waters. It is, therefore, suggested that microbial analysis of bottom sediments be considered a part of water-quality evaluations for rangeland streams.