The average depth of the Detroit River in its upper reach ranges from 35 to 50 feet. Serving as the connecting channel between Lake St. Clair and Lake Erie, the depths of the various areas of the Detroit River are influenced by the seasonal levels of these two reservoirs.
The Detroit River follows a 32-mile international course from its headwaters at Windmill Point Light in Lake St. Clair to its delta at Detroit River Light in Lake Erie. The river is divided into two reaches: the strait-like upper reach that flows from its source to Fighting Island and the wide lower reach dotted with islands and low-water stretches.
The water coming out of Lake St. Clair separates into two deep waterways at Peach Island. Further down Peach Island is Belle Isle, where the channel found north of the isle is separated by Scott Middle Ground. The depth of the water in this area ranges from 1 to 6 feet. The channels flanking Scott Middle Ground measure 19 to 30 feet deep. The water from Belle Isle then travels downstream to the source at Fighting Island. The deepest points of the Detroit River are located near Ambassador Bridge.
Beginning in the mid-1870s, various widening and deepening projects have been made around the Detroit River. In modern times, the Detroit River is one of the most important transportation routes between the United States and Canada.