Groundwater/Surface-Water Interactions Along Ellerbe Creek in Durham, North Carolina, 2016–18

Scientific Investigations Report 2019-5097
Prepared in cooperation with the City of Durham Public Works Department, Stormwater and GIS Services Division
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Abstract

An assessment of groundwater/surface-water interactions along Ellerbe Creek, a major tributary to upper Falls Lake in Durham County, North Carolina, was conducted from July 2016 to March 2018 to determine if groundwater is a likely source of elevated nitrate input to the stream. Groundwater/surface-water interactions were characterized by synoptic streamflow measurements, groundwater-level monitoring, hydrograph-separation methods, and a continuous streambed temperature survey to aid in the collection and interpretation of water-quality data. A streamflow gain-loss survey identified gaining and losing reaches within the stream and found that surface-water inflow, including that from a treated wastewater outfall, provided much of the streamflow gain within the study reach. Through the use of two hydrograph-separation methods, base flow for the Ellerbe Creek study reach was estimated to be between 14.0 and 17.7 cubic feet per second during the study period, contributing up to 57 percent of mean streamflow, with the remaining contributions coming from surface runoff to the stream. The effluent discharge accounted for most of the estimated base-flow contribution to the stream below the North Durham Water Reclamation Facility outfall. Hydraulic gradients within the groundwater were determined to flow upward and toward the stream during base-flow conditions and reverse during storm events. Nitrate concentrations ranged from below the method detection level to 2.69 milligrams per liter, with the highest concentrations just downstream from the wastewater outfall. Bank seeps and groundwater samples had lower nitrate concentrations than surface-water samples, ranging from below the method detection level to 1.04 milligrams per liter, with the highest concentration at the piezometer within the stream. Results indicate that groundwater is not a large component of streamflow within Ellerbe Creek nor a major source of nitrate within the study reach.

Suggested Citation

Antolino, D.J., 2019, Groundwater/surface-water interactions along Ellerbe Creek in Durham, North Carolina, 2016–18: U.S. Geological Survey Scientific Investigations Report 2019–5097, 32 p., https://doi.org/10.3133/sir20195097.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Groundwater/Surface-Water Interactions
  • Water-Quality Results
  • Summary and Conclusions
  • References Cited

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Groundwater/surface-water interactions along Ellerbe Creek in Durham, North Carolina, 2016–18
Series title Scientific Investigations Report
Series number 2019-5097
DOI 10.3133/sir20195097
Year Published 2019
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) South Atlantic Water Science Center
Description viii, 32 p.
Country United States
State North Carolina
County Durham County, Wake County
City Durham
Online Only (Y/N) Y
Additional Online Files (Y/N) N