On the other side of the river is the now-closed Sibley Generating Station, originally built in the 50’s and deactivated in late 2018. As may be seen if one looks closely, it is being torn down. The smokestack will probably be the last part to be removed.
@ALeventiy - Thanks! The ball is one of several attached to the power lines crossing the river, as a means of marking the wires to be seen by low-flying aircraft (uncommon, but possible). The balls are plastic or fiberglass, mounted over the individual wires, and are also used over certain railroad tracks.