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Streambed E. coli alters microbial water quality


Most of microbial quality regulations and assessments for fresh waters use the Escherichia coli as an indicator of fecal contamination that may bring to water microbes harmful for human health. Stream and lake bottom sediments contain large numbers of E. coli, and sediment reseuspension was shown to cause a substantial E. coli influx from sediments to the water column during high-flow storm events. However, relatively high concentrations of E. coli were also found in stream waters during low-flow periods.

In the January-February 2017 issue of the Journal of Environmental Quality, researchers report results of the study undertaken to see if streambeds may contribute E. coli to water during the low-flow periods. Application of the SWAT model to monitoring data of a Pennsylvania stream showed that E. coli concentrations in water during low-flow periods could not be satisfactorily estimated when E. coli influx to water was attributed only to the E. coli transport with runoff from manured fields and pastures without accounting for sediment sources.

Results demonstrate that release of E. coli from streambed sediments during low-flow periods is substantial, and that water column E. coli concentrations are strongly dependent on not only land management practices but also on in-stream processes.


Read the full article in JEQ. Free preview March 3 - March 10