Combined sewer overflows (CSOs) negatively affect water quality in urban river and lake systems worldwide by contributing thermally enhanced waters, particulates, and various organic and inorganic contaminants. Cities that utilize CSOs must reassess aging sewer systems or minimize the impact overflows have on water quality. The Buffalo River, which drains into northeastern Lake Erie, receives contaminants from various chemical, metallurgical, and petroleum industries. Rainfall events initiate discharge from over 40 CSOs located along the River and Canal shoreline and are known to mobilize contaminated bed sediments. Therefore, this paper will illustrate how empirically derived visualizations can characterize the geographic extent and parameterize effluent from CSOs and storm-induced suspended sediment. We used oceanographic profilers and a three-dimensional visualization software package (EVS-Pro) to collect and analyze water quality data and to create visual models of parameter responses to rainfall events and baseflow. The visualizations (a) captured a distinct “first flush” from CSOs and the River, characterized as plumes of thermally enhanced water, high in turbidity and low in dissolved oxygen, (b) revealed a well-defined westward trend of cooling water and decreasing suspended sediment, away from the urban area, and (c) indicated suspended sediments departing the mouth of the Buffalo River settle quickly. The combination of intense field monitoring with dataloggers and visualizations revealed large-scale patterns and discriminated localized departures from these patterns, which can help predict sediment sinks and sources, map the geographic dispersion of effluent matter, and guide remediation efforts.