Numerical Modeling and Field Investigation of Nitrate Loading from Septic Systems to Surface Water Bodies in the Bayou Chico Watershed, Pensacola, Fl

The environmental impacts of COVID-19 and the “new normal” of working from home are being explored in the scientific community. However, there is currently no published study on the COVID-19 impacts to nitrate load via septic systems. This study aims to determine the increase of septic system sourced nitrate load due to the COVID-19 pandemic associated restrictions and stay-at-home orders. A field investigation was conducted to collect nitrogen data that were compared with historical data and used for model validation. The numerical model ArcNLET (Nitrate Load Estimation Toolkit) was used to simulate the nitrogen transport and estimate the nitrate load from septic systems to surface water bodies. Nitrate concentrations of surface waterbodies increased during the time of this study compared to baseline levels from a 2016-2018 nitrogen speciation study by an average ratio of 2.6. The new data collected in this study is integrated with various model scenarios to estimate the change in nitrate load to surface water bodies. Household nitrate load increase scenarios were determined to be reasonable, where the septic system sourced nitrate concentrations at the water table may have increased by up to or greater than three-fold in comparison to the baseline concentrations. This study shows that the COVID-19 pandemic and the associated “new normal” led to an increase of nitrate load via septic systems within the study area.