The report documents the methodology and results for an input-output mass loading evaluation of organic contaminants, heavy metals, and conventional pollutants in the Trenton Channel, Detroit River. The project was one of many coordinated activities in the Upper Great Lakes Connecting Channels Study (UGLCCS) that focused on the St. Marys River, St. Clair River, Lake St. Clair, and the Detroit River. The U.S. Environmental Protection Agency, had primary responsibility for coordination, planning, and execution of the Trenton Channel project. Two 1986 surveys were conducted to describe concentration gradients in the water and to determine whether the channel acted as a source or a sink for the measured parameters. Intensive sampling was carried out at principal point sources discharging into the Trenton Channel and within the channel along three transects at the head and mouth of two segments during May 6-7 and August 26-27, 1986.