On Lighthouse Directory I also found:
Canadian-
Bar Point Pier
Hackett Reach Range Rear
Ballard Reef (Livingstone Channel Light 77D)
US-
Detroit Waterworks Intake Crib

I am not positive that all these are actually in the Detroit River. Of the above, Grosse Ile, Boblo and Pelee Passage are inactive so they wouldn't count toward "coverage". I find it hard to determine what body of water a lighthouse is located in, for the Great Lakes. I have a book I could check, but my husband packed away all my lighthouse books while I was in Oregon, and I haven't had a chance to bring them back downstairs.