This project will investigate and quantify pathways for people to be exposed to pathogens during floods. The research addresses the research priority on water related hazards and public health; in particular, we will explore the “intersections of land/water use, disease vector mechanisms, and water hazards [and] climate change.” Objectives are to (1) evaluate and compare pathways to exposure in different settings with different types of flooding and sources of contamination, (2) identify processes and mechanisms that lead to recovery from or resilience to the contamination, and (3) identify conditions that lead to vulnerability of various populations. The objectives will be addressed by modeling three sites with flooding: a major urban area subject to coastal flooding and mainly municipal sources of contamination, a large urban area on the shore of a Great Lake with both municipal and agricultural sources of contamination, and a city with combined coastal and riverine flooding and contamination from municipal and “informal” sources of contamination. Modeling of hydrodynamics and fate and transport of biological contaminants will be accomplished with the MIKE+ modeling suite, and it will take advantage of cases with data from the USGS. The project puts particular emphasis on evaluating exposure of socially vulnerable communities. The research leverages the work of PIs Ikuma and Rehmann in modeling coastal and riverine flooding in Loíza, Puerto Rico, complements previous and ongoing work of PI Lenaker in Milwaukee, and builds on a study by PIs Jackson and Rehmann on exposure of fish to fire retardant in streams