My primary research area is coastal water quality, and recently I have expanded my research to include activities on sanitation more broadly. The work on coastal water quality is focused on understanding the sources, transformation, transport, and ecology of biocolloids - specifically fecal indicator organisms, pathogens, and phytoplankton, as well as sources and fate of nitrogen and phosphorus. This knowledge is crucial to directing new policies, and management and engineering practices that protect human and ecosystem health along the coastal margin. The work on sanitation aims to develop microbial risk assessment models to gain a better understanding of how pathogens are transmitted to humans through their contact with water, feces, and contaminated surfaces. Research is focused on key problems in developed and developing countries. The goal is to design and test effective interventions and technologies for reducing the burden of infectious disease.