Investigating Variability in Nutrient and Enterococcus Concentrations in Tidal Floodwater
College
College of Sciences
Department
Ocean and Earth Sciences
Graduate Level
Master’s
Graduate Program/Concentration
Ocean and Earth Sciences
Presentation Type
Poster Presentation
Abstract
Tidal flooding is an increasingly pressing hazard in Norfolk, VA. The water quality impacts of this flooding on the Chesapeake Bay are not being accounted for in the current Total Maximum Daily Load. Alfonso Macías-Tapia demonstrated that the entire annual load allocation of nutrients for the Lafayette River watershed (a tributary of the Chesapeake Bay) could be delivered by a single “king tide” flood event (Macías-Tapia et al. 2023). High concentrations of Enterococcus bacteria have also been observed in tidal floodwaters, presenting public health risks. This study investigates differences in nutrient and Enterococcus concentrations in tidal floodwaters across different watersheds, land uses, and flooding routes (over land vs. through storm drains). Floodwaters in three watersheds in and around Norfolk, VA were sampled through multiple citizen science events, and weekly river sampling was performed to establish baseline concentrations. Floodwater concentrations of both parameters significantly exceeded baseline concentrations in every flood event. Significant differences in nutrient and Enterococcus loading between watersheds and between flooding routes were found in some events, but not in others. Future work will include expansion of citizen science events to collect more samples across a wider range of land uses and collection of higher resolution baseline data.
Keywords
Nutrients, Enterococcus, Fecal indicator bacteria, water quality, Tidal flooding
Investigating Variability in Nutrient and Enterococcus Concentrations in Tidal Floodwater
Tidal flooding is an increasingly pressing hazard in Norfolk, VA. The water quality impacts of this flooding on the Chesapeake Bay are not being accounted for in the current Total Maximum Daily Load. Alfonso Macías-Tapia demonstrated that the entire annual load allocation of nutrients for the Lafayette River watershed (a tributary of the Chesapeake Bay) could be delivered by a single “king tide” flood event (Macías-Tapia et al. 2023). High concentrations of Enterococcus bacteria have also been observed in tidal floodwaters, presenting public health risks. This study investigates differences in nutrient and Enterococcus concentrations in tidal floodwaters across different watersheds, land uses, and flooding routes (over land vs. through storm drains). Floodwaters in three watersheds in and around Norfolk, VA were sampled through multiple citizen science events, and weekly river sampling was performed to establish baseline concentrations. Floodwater concentrations of both parameters significantly exceeded baseline concentrations in every flood event. Significant differences in nutrient and Enterococcus loading between watersheds and between flooding routes were found in some events, but not in others. Future work will include expansion of citizen science events to collect more samples across a wider range of land uses and collection of higher resolution baseline data.