“Up to 500 carp died over the weekend at Kensington Metropark’s Kent Lake and portions of the Huron River, likely due to a virus called spring viremia of carp, according to the Michigan Department of Natural Resources.”
The spring viremia virus is only known to affect carp and poses no threats to humans or other animals. However, the rotting corpses are being cleaned up by Metropark Staff to minimize the odor and prevent possible E.Coli contamination.
See this article from the Livingston Daily.