Water-quality samples collected from drainage canals, from Lake Pontchartrain, La., and from flood waters contained contaminants typically found in waters influenced by urban runoff. Pesticides and wastewater compounds were detected in all water samples, but none exceeded U.S. Environmental Protection Agency (EPA) drinking water or aquatic life criteria. Although metals were detected in all samples, copper, nickel, and silver occurred in concentrations greater than water-quality criteria for salt water. Salinity levels in the freshwater marshes south of New Orleans were typical of Gulf of Mexico waters for an extended period of time, and levels did not return to prehurricane levels until February 2006.