Spatiotemporal variation of bacterial water quality and the relationship with pasture land cover

Abstract

Pathogens are a major cause of water quality impairment and public health concern world-wide.In the United States, each state is tasked with developing water quality standards (WQS) to protect the designated use(s) of waterbodies. Several streams in the Illinois River Watershed in northwest Arkansas are currently listed as impaired due to elevated levels of pathogens. Our objective was to evaluate Escherichia coli (E. coli) numbers at 29 stream sites, compare these numbers to the applicable WQS, and investigate the relationship between E. coli numbers and land cover variables.E. coli numbers in samples collected at most sites were within allowable limits, although there were several instances of violations of the WQS. Violations were variable from year to year at some sites, and elevated levels of E. coli were spatially localized during baseflow. Violations also were positively related to pasture land cover in the drainage area, and particularly within the riparian buffer area.This relationship was non-linear, or threshold based, where there was a significant increase in the mean E. coli exceedances when riparian pasture land cover was greater than approximately 50%.These results can be used to identify specific stream reaches where E. coli numbers might be elevated and the implementation of best management practices can be geographically targeted.

Spatial Patterns of Escherichia coli Concentrations in Sediment before and after High‐Flow Events in a First‐Order Creek

“…The dominant flow conditions might cause the differences in concentrations among sampling locations. Scott et al (2017) noted that during base‐flow conditions, sources of bacteria can be localized because bacteria are less likely to be transported great distances downstream during low flows due to slower water velocities, greater predation, and increased presence of pools and increased settling into the stream bed sediments. Piorkowski et al (2014b) reported significant differences in E. coli concentrations in sediments between those found in riffles and those found in pools, which they attributed to lower velocities and higher settling rates of fine particles, which are associated with E. coli attachment.…”

El rol de los bañados de desborde fluvial en la retención de nutrientes y su actividad metabólica

“…Los resultados mostraron también un patrón de densidad máxima de E. coli en el tramo Medio de los cauces periurbanos caracterizados como BDF mejor conservados. Patrones similares fueron publicados en otros trabajos (Collins, 2004;Scott et al, 2017). Para Collins (2004) las altas densidades de bacterias reflejan la fracción desproporcionadamente grande del flujo superficial y subsuperficial de la cuenca que pasa a través de los humedales y, por tanto, actúan como sumideros de microorganismos.…”

Groundwater Seeps: Portholes to Evaluate Groundwater’s Influence on Stream Water Quality

“…Approaches to protect riparian seep areas include riparian fencing, off‐stream water sources, stream crossings, riparian buffers, and grazing management (Agouridis et al ; Swanson et al ). Although relationships with riparian pasture cover and increased E. coli have been documented (Scott et al ), limited studies have evaluated seep E. coli transport in pasture lands (Collins and Rutherford ). Collins and Rutherford () developed a model to simulate E. coli and used field measurements to illustrate elevated E. coli inputs from seepage areas accessed by cattle (10 4 to 10 8 MPN) during base flow and rain events.…”