Richard L. Whitman Meredith B. Nevers Mantha S. Phanikumar Muruleedhara N. Byappanahalli Zhongfu Ge 2012 Numerical simulations of the transport and fate of <i>Escherichia coli</i> were conducted at Chicago's 63rd Street Beach, an embayed beach that had the highest mean <i>E. coli</i> concentration among 23 similar Lake Michigan beaches during summer months of 2000-2005, in order to find the cause for the high bacterial contamination. The numerical model was based on the transport of <i>E. coli</i> by current circulation patterns in the embayment driven by longshore main currents and the loss of <i>E. coli</i> in the water column, taking settling as well as bacterial dark- and solar-related decay into account. Two <i>E. coli</i> loading scenarios were considered: one from the open boundary north of the embayment and the other from the shallow water near the beachfront. Simulations showed that the embayed beach behaves as a sink for <i>E. coli</i> in that it generally receives <i>E. coli</i> more efficiently than it releases them. This is a result of the significantly different hydrodynamic forcing factors between the inside of the embayment and the main coastal flow outside. The settled <i>E. coli</i> inside the embayment can be a potential source of contamination during subsequent sediment resuspension events, suggesting that deposition-resuspension cycles of <i>E. coli</i> have resulted in excessive bacterial contamination of beach water. A further hypothetical case with a breakwater shortened to half its original length, which was anticipated to enhance the current circulation in the embayment, showed a reduction in <i>E. coli</i> concentrations of nearly 20%. application/pdf 10.4319/lo.2012.57.1.0362 en ASLO Nearshore hydrodynamics as loading and forcing factors for <i>Escherichia coli</i> contamination at an embayed beach article