The Identification and Quantification of Sewage Contamination in the Milwaukee Estuary

Abstract

Sewage contamination from failing infrastructure and sewer overflows is a major environmental and human health concern in waterways, especially in urban communities bordering the Great Lakes such as Milwaukee, Wisconsin. Culture-based fecal indicator bacteria, such as Escherichia coli, enterococci, and fecal coliforms are traditionally used to indicate the presence of a human health risk due to fecal contamination. These indicators, however, fail to distinguish between sources of fecal contamination (human vs. non-human). Two human-specific fecal indicators, human Bacteroides and human Lachnospiraceae, were used to identify and quantify sewage contamination in the Milwaukee estuary, which discharges to Lake Michigan, as well as the Milwaukee, Menomonee, and Kinnickinnic Rivers immediately upstream. Chapter 1 provides an overview of the health and environmental impacts of fecal pollution in waterways and the use of alternative indicators to track sewage pollution. Chapter 2 describes the concentrations of human fecal indicators, used as a proxy for human sewage, in the three urban rivers upstream of the Milwaukee estuary and how this information can be used for the implementation stage of the current fecal coliforms Total Maximum Daily Load (TMDL) process. Chapter 3 describes how human fecal indicators were used to characterize sewage contamination across the hydrograph. Intensive monitoring at sites in the rivers and the estuary was used to calculate event loads for storm and combined sewer overflow events and investigate relationships between loads and the degree of watershed urbanization and the amount of rainfall during an event. Chapter 4 discusses how the information generated in this research can be used in the TMDL implementation process and can be used to focus efforts of local agencies and municipalities to investigate and remediate unrecognized sources of sewage contamination. More specific information about sources of fecal pollution will be useful to create appropriate water quality goals to address the human health concerns of sewage contamination.