It happened sometime before Sunday morning - with separate incidents along Loveland's river walk and even nearby schools.
Sgt. Mike Halloran with Loveland Police says more than 30 different reports have come in with far more individual incidents than that.
At Thompson Valley High School, graffiti was found on the roof and on the outside of the building.
"We think that it is not gang related, it looks like tagger behavior rather than gang behavior," Halloran said.
The tagging happened at various residences, under a bridge, on park benches and even on the inside of a portable toilet.
Police believe two separate people, or groups, are responsible, since the graffiti in different locations appeared to be so different.
If you have any information, you're asked to call 970-962-2032.
(KUSA-TV © 2013 Multimedia Holdings Corporation)