title: Groundwater and stream E. coli concentrations in coastal plain watersheds served by onsite wastewater and a municipal sewer treatment system.
abstract: The goal of this study was to determine if onsite wastewater treatment systems (OWS) were influencing groundwater and surface water Escherichia coli concentrations in a coastal plain watershed. Piezometers for groundwater monitoring were installed at four residences served by OWS and five residences served by a municipal wastewater treatment system (MWS). The residences were located in two different, but nearby (<3 km), watersheds. Effluent from the four septic tanks, groundwater from piezometers, and the streams draining the OWS and MWS watersheds were sampled on five dates between September 2011 and May 2012. Groundwater E. coli concentrations and specific conductivity were elevated within the flow path of the OWS and near the stream, relative to other groundwater sampling locations in the two watersheds. Groundwater discharge in the OWS watershed could be a contributor of E. coli to the stream because E. coli concentrations in groundwater at the stream bank and in the stream were similar. Stream E. coli concentrations were higher for the OWS in relation to MWS watersheds on each sampling date. Water quality could be improved by ensuring OWS are installed and operated to maintain adequate separation distances to water resources.
authors.affiliation: Environmental Health Sciences Program, East Carolina University, 3408 Carol Belk Building, Greenville, NC 27858, USA E-mail: humphreyc@ecu.edu.
authors.forename: Charles
authors.initials: C
authors.lastname: Humphrey
authors.affiliation: Environmental Health Sciences Program, East Carolina University, 3400 Carol Belk Building Greenville, NC 27858, USA.
authors.forename: Algernon
authors.initials: A
authors.lastname: Finley
authors.affiliation: Department of Geological Sciences, East Carolina University, 204 Graham, Greenville, NC 27858, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: O'Driscoll
authors.affiliation: Department of Geological Sciences, Institute for Coastal Science and Policy, East Carolina University, 387 Flanagan, Greenville, NC 27858, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Manda
authors.affiliation: Coastal Resources Management Program, East Carolina University, 379 Flanagan, Greenville, NC 27858, USA.
authors.forename: Guy
authors.initials: G
authors.lastname: Iverson
mesh_terms: D004926:Escherichia coli / Q000302:isolation & purification*; D060587:Groundwater / Q000382:microbiology*; D009657:North Carolina; D045483:Rivers / Q000382:microbiology*; D014865:Waste Disposal, Fluid; D062065:Wastewater; D060753:Water Quality
chemical_list: D062065:Wastewater