Assessing the contribution of groundwater to phosphorous loadings to canals and tributaries discharging to Biscayne Bay

In 2019 and 2020 Miami-Dade County (MDC) conducted an effort to characterize nutrient concentrations in north Dade using existing shallow groundwater wells at permitted industrial sites. This previous survey showed concerning high concentrations of total phosphorous (TP) in many sites near tributaries, canals and water bodies that likely contribute to direct discharges to Biscayne Bay. This project revisit 10 sites which were each re-sampled in April and May 2023. Sampling was conducted by MDC and the chemical analysis was performed by Florida International University. With varying results between sites, the data confirms the high concentration of TP and indicates the contribution of multiple intermittent sources of pollution to the groundwater.