This report, a product of the Lake St. Clair Regional Monitoring Project, describes four water-quality studies in the St. Clair River/Lake St. Clair Basin from the early 1970's through 2005. All the studies examined water quality of streams in the basin; the most recent studies focused primarily on water quality during high- and low-streamflows. This report explains how storm-runoff and low-flow periods affect water quality in the basin. Included is a summary of stream-water quality findings from the National Stream Quality Accounting Network (1973-95); the National Water-Quality Assessment (1996-98); the Oakland County Land-Use Change study (2001-03); and the Lake St. Clair Regional Monitoring Project (2004-05).