Bill, yesterday, asked why the hydroelectric plant on Belle Isle was abandoned. Here's Wikipedia's scoop on the matter as well as another excellent question to ponder:
"Silt in river water wore down turbine blades, bearings and bushings. Logs and debris damaged the entrance gates of the mill race and mud had to be cleaned up after floods. Power production varied with river flow and was always low in summer.
In the mid 1950’s the price of oil was so low that petroleum products became the fuel of choice (local gasoline was .25 a gallon). Had anyone foreseen the great increase in costs after the Arab Oil Embargo in 1967, this plant might have remained competitive. Question: would power production have been as valuable as the recreational benefits we now have from a free flowing river?"