This map (with an interesting take on the Detroit border) is unfortunately timely in its discovery after the recent flooding. The map is a part of a 1981 study of flood insurance and flood plain issues in Detroit.
“This Flood Insurance Study investigates the existence and severity of flood hazards in the City of Detroit, Wayne County, Michigan, […]”
The study was to cover areas of low development for potential upcoming flood risk as far into the future as 1983 and there was a focus on the shoreline because it was highly developed and “susceptible to flooding and erosion.” The report later notes that the shoreline area of the City of Detroit had a very low likelihood of flooding. There haven’t been ferry boats on Downtown streets since composite photography made some stunning fake postcards in the early 20th century.
The 1970s also saw some serious flooding:
“One of the most sever recent storms which affected the eastern portion of Detroit occurred on November 13 and 14, 1972. Storms on these dates, combined with a high lake St. Clair level, caused flooding which inundated approximately 800 homes within the city. This resulted in gross property damage estimated at $2 million. The storm of March 17 and 18, 1973, inundated an estimated 600 acres of the urban Detroit area.”
The study’s final recommendations were to develop a floodway that could handle a 100-year flood. It seems that the recommendations of this report were not followed.