Following the Louisiana landfalls of Katrina on August 29 and Rita on September 24, 2005, the local population and the American public were concerned about the effects the hurricanes might have on water quality in Lake Pontchartrain. The lake is a major recreational resource for the region and an important fishery. Contamination carried by the storm surge—along with runoff and water pumped from flooded areas of New Orleans—was considered a serious threat to the water body. The USGS, in collaboration with the LDEQ, monitored the sanitary quality of water at 22 sites in and around Lake Pontchartrain, La., for 3 consecutive weeks from September 13 to 29, 2005 (fig. 1). A subsequent multipleagency survey of 30 sites within Lake Pontchartrain was undertaken by the U.S. Environmental Protection Agency (EPA), the USGS, and the National Oceanic and Atmospheric Administration during the week of October 11–14, 2005, to evaluate the effects of the hurricanes and overall levels of fecal contamination on the water quality of the lake (see Heitmuller and Perez, this volume). In addition, the EPA monitored fecal-indicator concentrations at a variety of sites in New Orleans, surrounding areas, and the Mississippi River between September 3 and October 22, 2005 (U.S. Environmental Protection Agency, 2006). This article describes fecal-indicator bacteria concentration results collected by USGS in the context of other existing data.