The hydrant in the Detroit suburb of Mount Clemens had been painted white with black spots in August by children as part of a citywide art project, and Gloria Haller painted it yellow in September.
Haller argued safety was at stake, and the black-and-white hydrant would be difficult to see in the winter.
Haller was charged with misdemeanors of defacing public property and violating the fire code. The Macomb Daily and The Detroit News report District Judge Sheila Miller dismissed the charges Thursday.
Haller faced up to 90 days in jail and a $500 fine if convicted.