Analysis and Simulation of Bacterial Contamination on an Urban Beach at Lake Michigan

Abstract

E. coli and enterococci are indicators of sewage pollution, and understanding their transfer and life cycle is important to maintaining a clean and healthy beach. While near-shore lake water is extensively monitored for bacteria levels, it has been suggested that the sand itself can serve as a reservoir and medium of bacterial growth. We report on experiments confirming that both E. coli and enterococci are capable of surviving in Bradford Beach sand. In order to explore the potential contribution of bacteria living in the sand to elevated bacteria levels in lake water, we develop a mathematical model that represents moisture transport, bacteria and nutrient growth in beach sand. Computational simulations confirm the feasibility of the modeling approach coupling physical and biological dynamics.