A numerical circulation model of Tampa Bay Florida is used to simulate the flow field and tidal residual circulation for 2001 to present. Three methods are used to study the transport of Harmful Algal Blooms (HABs) and human pathogens in Tampa Bay. A Lagrangian method is used as a particle tracking device to simulate the path of HABs and human enteroviruses within the bay. Source locations of pathogens into the bay are located and used as release points for tracking purposes. Grid cells are filled with particles near the sources to simulate transport of the pathogens within the bay. Simulations will be coupled with water samples taken from various locations within the bay for correlation with the model. Contamination levels in the bay are being measured through microbiological analysis by a team of biological oceanographers. Simulations also are being evaluated against data from the Environmental Protection Commission of Hillsborough County for comparisons of total coliforms and fecal coliforms in the bay. The purpose of the study is to investigate particle trajectories in Tampa Bay in order to predict how pathogens entered the bay, where they are transported within the bay, how fast they are moving and their residence time in the bay (Fig. 13). The data gathered from this study is being used to implement marine monitoring protocols for Tampa Bay and in the test and evaluation of the Autonomous Microbial Genosensor developed by J. Paul under another component of this grant. Lutherís portion of this project supported one Ph.D. student.