Environmental Health Threats Associated with Drainage from a Coastal Urban Watershed

Abstract

The project goal was to determine if stormwater runoff and the legacy effects of leaking underground storage tanks (UST) posed an environmental health threat along an urban stream, Town Creek (TC). Baseflow and stormflow samples were collected from TC between March and October 2016 for physical and chemical characterization and E. coli analyses. Groundwater seeps and wells near the banks of TC were also sampled for E. coli and benzene analyses. Stormflow concentrations of E. coli were significantly (p < 0.05) elevated relative to preceding baseflow and groundwater concentrations. Overall, 80% of stormflow samples and 45% of baseflow samples exceeded the US EPA recommended standards for E. coli in recreational waters. Benzene was detected in all water samples analyzed and 50% of samples collected from a seep on the western bank of TC exceeded the maximum contaminant level. Concentrations of benzene emitted to air from contaminated soil exceeded short term exposure standards 75% of times sampled. Results suggest the drainage from TC may be a threat to environmental health. Implementation of stormwater control measures is suggested to reduce the delivery of runoff and E. coli to TC. Remediation of groundwater contaminated by leaking underground storage tanks is also suggested.

Real‐Time Estimates ofEscherichia coliConcentrations Using Ultraviolet‐Visible Spectrometers

“…Average annual rainfall in the watershed is 126 cm, with precipitation being higher during the summer months. Previous monitoring indicated that Town Creek was known to have elevated E. coli concentrations that varied based on flow conditions (Humphrey et al, 2018). Town Creek discharges to the Tar River, which is classified as secondary recreation waters at this location because water‐based recreation, including kayaking and fishing, are popular in the area.…”

“…Because of the documented relationship between flow and E. coli concentrations (Humphrey et al, 2018), breaking the data into base flow and storm flow subsets would have been logical for this study. Flow data was not available in this stream during the study period; hence, it could not be used in this work.…”

“…The use of spectrometers paired with a regression model may have the potential to estimate bacteria concentrations with a waiting time of seconds instead of hours. Our hypothesis, that this method would produce acceptable results, was based on bacteria concentrations in the studied stream being altered substantially by rainfall events (Humphrey et al, 2018), which also alter the concentrations of chemicals that absorb light (e.g., nitrate, organic matter). The goal of this study was to test a quicker way to estimate bacteria concentrations in streams than currently accepted practices that often require more than 18 h to get results.…”

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

“…Seeps can bestow water quality services by contributing to food webs (Williams ) and by attenuation of contaminants (O’Driscoll and DeWalle ). However, seeps can also act as net contaminant sources (Williams et al , ; Humphrey et al ). From a water quality perspective, seeps can provide portholes to observe groundwater quality.…”

“…Although seeps may make up a relatively small extent of a catchment, they are important components of the watershed ecosystem because of their capability to translate groundwater contaminants to streams and wetlands (Williams et al ; Humphrey et al ) and act as nutrient cycling (McClain et al ) and ecological diversity hotpots (Stevens and Meretsky ; Griebler and Avramov ; Williams ). Springs and seeps are key aquatic habitats because they exert a broad influence on regional ecosystem structure, function, and evolutionary processes (Stevens and Meretsky ).…”