This map from MLive shows roads closed due to flooding in Western Michigan. (Turn around, don't drown). Click through for the interactive version.
A similar map from NOAA shows flood gauge readings across the area.
The purple gauge in this above map is Grand Rapids at Comstock Park, which is showing flooding at almost 6 feet above flood stage.
The historical big flood in Grand Rapids is from 1904; this collection rephotographs scenes from that flood in 2004.